From 39987109948a29b37acf91317e8d4cea2c0290d0 Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Sun, 16 Jun 2024 00:25:35 +0200
Subject: [PATCH 01/25] comptime: support `-cv key=value` and `var :=
 $compile_value/2`

---
 vlib/v/ast/ast.v                              | 42 ++++++++++---------
 vlib/v/checker/comptime.v                     | 12 ++++++
 .../comptime_const/using_comptime_const.vv    | 15 +++++++
 vlib/v/gen/c/comptime.v                       | 11 +++++
 vlib/v/parser/comptime.v                      | 26 ++++++++++--
 vlib/v/pref/pref.v                            | 17 ++++++++
 6 files changed, 100 insertions(+), 23 deletions(-)
 create mode 100644 vlib/v/checker/tests/comptime_const/using_comptime_const.vv

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 27308b32ac4c17..5955f9a05a628a 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -1913,26 +1913,28 @@ pub mut:
 @[minify]
 pub struct ComptimeCall {
 pub:
-	pos          token.Pos
-	has_parens   bool // if $() is used, for vfmt
-	method_name  string
-	method_pos   token.Pos
-	scope        &Scope = unsafe { nil }
-	is_vweb      bool
-	is_embed     bool
-	is_env       bool
-	env_pos      token.Pos
-	is_pkgconfig bool
-pub mut:
-	vweb_tmpl   File
-	left        Expr
-	left_type   Type
-	result_type Type
-	env_value   string
-	args_var    string
-	args        []CallArg
-	embed_file  EmbeddedFile
-	or_block    OrExpr
+	pos              token.Pos
+	has_parens       bool // if $() is used, for vfmt
+	method_name      string
+	method_pos       token.Pos
+	scope            &Scope = unsafe { nil }
+	is_vweb          bool
+	is_embed         bool // $embed_file(...)
+	is_env           bool // $env(...)
+	is_compile_value bool // $compile_value(...)
+	env_pos          token.Pos
+	is_pkgconfig     bool
+pub mut:
+	vweb_tmpl     File
+	left          Expr
+	left_type     Type
+	result_type   Type
+	env_value     string
+	compile_value string
+	args_var      string
+	args          []CallArg
+	embed_file    EmbeddedFile
+	or_block      OrExpr
 }
 
 pub struct None {
diff --git a/vlib/v/checker/comptime.v b/vlib/v/checker/comptime.v
index 27a6b7a3ef96ed..20b1a17da55a93 100644
--- a/vlib/v/checker/comptime.v
+++ b/vlib/v/checker/comptime.v
@@ -29,6 +29,18 @@ fn (mut c Checker) comptime_call(mut node ast.ComptimeCall) ast.Type {
 		node.env_value = env_value
 		return ast.string_type
 	}
+	if node.is_compile_value {
+		arg := node.args[0] or {
+			c.error('\$compile_value takes two arguments', node.pos)
+			return ast.void_type
+		}
+		typ := arg.expr.get_pure_type()
+		value := c.pref.compile_compile_values[node.args_var] or { arg.str() }
+		node.compile_value = value
+		node.result_type = typ
+
+		return typ
+	}
 	if node.is_embed {
 		if node.args.len == 1 {
 			embed_arg := node.args[0]
diff --git a/vlib/v/checker/tests/comptime_const/using_comptime_const.vv b/vlib/v/checker/tests/comptime_const/using_comptime_const.vv
new file mode 100644
index 00000000000000..29c50f9906c026
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_const/using_comptime_const.vv
@@ -0,0 +1,15 @@
+//#flag -I $const('my_const','some_value')/xyz
+//#include "$const('my_const','some_value')/stdio.h"
+
+const my_int = $compile_value('my_int',4)
+const my_string = $compile_value('my_string','five')
+
+fn main() {
+	println(my_int)
+	println(my_string)
+  int_compile_value := $compile_value('my_const',5)
+	println(int_compile_value)
+  float_compile_value := $compile_value('my_float',1.0)
+  println(float_compile_value)
+	println('done')
+}
diff --git a/vlib/v/gen/c/comptime.v b/vlib/v/gen/c/comptime.v
index c1d198d1d52e64..0565b8bacf1b86 100644
--- a/vlib/v/gen/c/comptime.v
+++ b/vlib/v/gen/c/comptime.v
@@ -52,6 +52,17 @@ fn (mut g Gen) comptime_call(mut node ast.ComptimeCall) {
 		g.write('_SLIT("${val}")')
 		return
 	}
+	if node.method_name == 'compile_value' {
+		// $compile_value('some_string',<default value>)
+		val := util.cescaped_path(node.compile_value)
+		// dump(node)
+		if node.result_type == ast.string_type {
+			g.write('_SLIT("${val}")')
+		} else {
+			g.write('${val}')
+		}
+		return
+	}
 	if node.method_name == 'res' {
 		if node.args_var != '' {
 			g.write('${g.defer_return_tmp_var}.arg${node.args_var}')
diff --git a/vlib/v/parser/comptime.v b/vlib/v/parser/comptime.v
index 42c5fb21218746..bf06214406f2f2 100644
--- a/vlib/v/parser/comptime.v
+++ b/vlib/v/parser/comptime.v
@@ -8,7 +8,7 @@ import v.ast
 import v.token
 
 const supported_comptime_calls = ['html', 'tmpl', 'env', 'embed_file', 'pkgconfig', 'compile_error',
-	'compile_warn', 'res']
+	'compile_warn', 'compile_value', 'res']
 const comptime_types = ['map', 'array', 'array_dynamic', 'array_fixed', 'int', 'float', 'struct',
 	'interface', 'enum', 'sumtype', 'alias', 'function', 'option', 'string']
 
@@ -106,7 +106,7 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 	}
 	start_pos := p.tok.pos()
 	p.check(.dollar)
-	error_msg := 'only `\$tmpl()`, `\$env()`, `\$embed_file()`, `\$pkgconfig()`, `\$vweb.html()`, `\$compile_error()`, `\$compile_warn()` and `\$res()` comptime functions are supported right now'
+	error_msg := 'only `\$tmpl()`, `\$env()`, `\$embed_file()`, `\$pkgconfig()`, `\$vweb.html()`, `\$compile_error()`, `\$compile_warn()`, `\$compile_value()` and `\$res()` comptime functions are supported right now'
 	if p.peek_tok.kind == .dot {
 		name := p.check_name() // skip `vweb.html()` TODO
 		if name != 'vweb' && name != 'veb' {
@@ -122,7 +122,6 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 	}
 	is_embed_file := method_name == 'embed_file'
 	is_html := method_name == 'html'
-	// $env('ENV_VAR_NAME')
 	p.check(.lpar)
 	arg_pos := p.tok.pos()
 	if method_name in ['env', 'pkgconfig', 'compile_error', 'compile_warn'] {
@@ -160,6 +159,27 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 			method_name: method_name
 			pos: start_pos.extend(p.prev_tok.pos())
 		}
+	} else if method_name == 'compile_value' {
+		const_string := p.tok.lit
+		// const_name_pos := p.tok.pos()
+		p.check(.string)
+		p.check(.comma)
+		arg_expr := p.expr(0)
+		args := [
+			ast.CallArg{
+				expr: arg_expr
+				pos: p.tok.pos()
+			},
+		]
+		p.check(.rpar)
+		return ast.ComptimeCall{
+			scope: unsafe { nil }
+			is_compile_value: true
+			method_name: method_name
+			args_var: const_string
+			args: args
+			pos: start_pos.extend(p.prev_tok.pos())
+		}
 	}
 	has_string_arg := p.tok.kind == .string
 	mut literal_string_param := if is_html && !has_string_arg { '' } else { p.tok.lit }
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index f37fc529cb5ae8..76cecb8e95e968 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -193,6 +193,8 @@ pub mut:
 	// -d vfmt and -d another=0 for `$if vfmt { will execute }` and `$if another ? { will NOT get here }`
 	compile_defines     []string // just ['vfmt']
 	compile_defines_all []string // contains both: ['vfmt','another']
+	// -compile_value key=value
+	compile_compile_values map[string]string
 	//
 	run_args     []string // `v run x.v 1 2 3` => `1 2 3`
 	printfn_list []string // a list of generated function names, whose source should be shown, for debugging
@@ -823,6 +825,12 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 				res.build_options << '${arg} "${res.ldflags.trim_space()}"'
 				i++
 			}
+			'-cv', '-compile-value' {
+				if compile_value := args[i..][1] {
+					res.parse_compile_value(compile_value)
+				}
+				i++
+			}
 			'-d', '-define' {
 				if define := args[i..][1] {
 					res.parse_define(define)
@@ -1170,6 +1178,15 @@ pub fn cc_from_string(s string) CompilerType {
 	}
 }
 
+fn (mut prefs Preferences) parse_compile_value(define string) {
+	define_parts := define.split('=')
+	if define_parts.len == 2 {
+		prefs.compile_compile_values[define_parts[0]] = define_parts[1]
+		return
+	}
+	eprintln_exit('V error: Define argument value missing for ${define}.')
+}
+
 fn (mut prefs Preferences) parse_define(define string) {
 	define_parts := define.split('=')
 	prefs.diagnose_deprecated_defines(define_parts)

From a3ee35af91cfd170ee992dc4c9b7ecaf03d9641b Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Sun, 16 Jun 2024 12:52:15 +0200
Subject: [PATCH 02/25] comptime: add `vfmt` support, tests, CI job for
 `$compile_value`

---
 .github/workflows/comptime_ci.yml             | 51 +++++++++++++++++++
 cmd/tools/vast/vast.v                         |  1 +
 vlib/v/checker/checker.v                      |  8 +++
 vlib/v/checker/comptime.v                     | 51 +++++++++++++++++--
 .../comptime_const/using_comptime_const.vv    | 15 ------
 .../default_comptime_values_test.v            | 13 +++++
 .../comptime_value/parser_errors_1.run.out    |  3 ++
 .../tests/comptime_value/parser_errors_1.vv   |  1 +
 .../use_flag_comptime_values.vv               | 15 ++++++
 .../using_comptime_value.run.out              |  3 ++
 .../comptime_value/using_comptime_value.vv    | 11 ++++
 vlib/v/fmt/fmt.v                              |  9 ++++
 vlib/v/fmt/tests/comptime_value_keep.vv       |  7 +++
 vlib/v/gen/c/comptime.v                       |  3 +-
 14 files changed, 172 insertions(+), 19 deletions(-)
 create mode 100644 .github/workflows/comptime_ci.yml
 delete mode 100644 vlib/v/checker/tests/comptime_const/using_comptime_const.vv
 create mode 100644 vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
 create mode 100644 vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
 create mode 100644 vlib/v/checker/tests/comptime_value/parser_errors_1.vv
 create mode 100644 vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
 create mode 100644 vlib/v/checker/tests/comptime_value/using_comptime_value.run.out
 create mode 100644 vlib/v/checker/tests/comptime_value/using_comptime_value.vv
 create mode 100644 vlib/v/fmt/tests/comptime_value_keep.vv

diff --git a/.github/workflows/comptime_ci.yml b/.github/workflows/comptime_ci.yml
new file mode 100644
index 00000000000000..78cc6c3c9d4255
--- /dev/null
+++ b/.github/workflows/comptime_ci.yml
@@ -0,0 +1,51 @@
+name: Time CI
+
+on:
+  push:
+    paths:
+      - 'vlib/**'
+      - '**/comptime_ci.yml'
+      - '!**.md'
+  pull_request:
+    paths:
+      - 'vlib/**'
+      - '**/comptime_ci.yml'
+      - '!**.md'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref == 'refs/heads/master' && github.sha || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test-comptime-linux:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build V
+        run: make
+      - name: Test -cv values
+        run: ./v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+      - name: Test -compile-value values
+        run: ./v -compile-value my_f64=2.0 -compile-value my_int=3 -compile-value my_string="a four" -compile-value my_bool=true -compile-value my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+
+  test-comptime-macos:
+    runs-on: macos-14
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build V
+        run: make
+      - name: Test -cv values
+        run: ./v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+      - name: Test -compile-value values
+        run: ./v -compile-value my_f64=2.0 -compile-value my_int=3 -compile-value my_string="a four" -compile-value my_bool=true -compile-value my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+
+  test-time-windows:
+    runs-on: windows-2019
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build V
+        run: .\make.bat
+      - name: Test -cv values
+        run: ./v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+      - name: Test -compile-value values
+        run: ./v -compile-value my_f64=2.0 -compile-value my_int=3 -compile-value my_string="a four" -compile-value my_bool=true -compile-value my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
diff --git a/cmd/tools/vast/vast.v b/cmd/tools/vast/vast.v
index f5374757244ebe..21999af3a9d82d 100644
--- a/cmd/tools/vast/vast.v
+++ b/cmd/tools/vast/vast.v
@@ -1019,6 +1019,7 @@ fn (t Tree) comptime_call(node ast.ComptimeCall) &Node {
 	obj.add_terse('result_type', t.type_node(node.result_type))
 	obj.add('scope', t.scope(node.scope))
 	obj.add_terse('env_value', t.string_node(node.env_value))
+	obj.add_terse('compile_value', t.string_node(node.compile_value))
 	obj.add('pos', t.pos(node.pos))
 	obj.add_terse('args', t.array_node_call_arg(node.args))
 	obj.add_terse('or_block', t.or_expr(node.or_block))
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 0eb5fff545a1ab..a07896f2053dd4 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -2428,6 +2428,10 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 				}
 				node.main = env
 			}
+			if flag.contains('\$compile_value(') {
+				c.error('\$compile_value is not supported in ${node.kind} yet', node.pos)
+				return
+			}
 			flag_no_comment := flag.all_before('//').trim_space()
 			if node.kind == 'include' || node.kind == 'preinclude' {
 				if !((flag_no_comment.starts_with('"') && flag_no_comment.ends_with('"'))
@@ -2511,6 +2515,10 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 					return
 				}
 			}
+			if flag.contains('\$compile_value(') {
+				c.error('\$compile_value is not supported in ${node.kind} yet', node.pos)
+				return
+			}
 			for deprecated in ['@VMOD', '@VMODULE', '@VPATH', '@VLIB_PATH'] {
 				if flag.contains(deprecated) {
 					if !flag.contains('@VMODROOT') {
diff --git a/vlib/v/checker/comptime.v b/vlib/v/checker/comptime.v
index 20b1a17da55a93..1f855fd429935f 100644
--- a/vlib/v/checker/comptime.v
+++ b/vlib/v/checker/comptime.v
@@ -31,14 +31,23 @@ fn (mut c Checker) comptime_call(mut node ast.ComptimeCall) ast.Type {
 	}
 	if node.is_compile_value {
 		arg := node.args[0] or {
-			c.error('\$compile_value takes two arguments', node.pos)
+			c.error('\$compile_value takes two arguments, a string and a primitive literal',
+				node.pos)
+			return ast.void_type
+		}
+		if !arg.expr.is_pure_literal() {
+			c.error('-cv/-compile-value values can only be pure literals', node.pos)
 			return ast.void_type
 		}
 		typ := arg.expr.get_pure_type()
-		value := c.pref.compile_compile_values[node.args_var] or { arg.str() }
+		arg_as_string := arg.str().trim('`"\'')
+		value := c.pref.compile_compile_values[node.args_var] or { arg_as_string }
+		validate_type_string_is_pure_literal(typ, value) or {
+			c.error(err.msg(), node.pos)
+			return ast.void_type
+		}
 		node.compile_value = value
 		node.result_type = typ
-
 		return typ
 	}
 	if node.is_embed {
@@ -581,6 +590,42 @@ fn (mut c Checker) eval_comptime_const_expr(expr ast.Expr, nlevel int) ?ast.Comp
 	return none
 }
 
+fn validate_type_string_is_pure_literal(typ ast.Type, str string) ! {
+	if typ == ast.bool_type {
+		if !(str == 'true' || str == 'false') {
+			return error('bool literal `true` or `false` expected, found "${str}"')
+		}
+	} else if typ == ast.char_type {
+		if str.starts_with('\\') {
+			if str.len <= 1 {
+				return error('empty escape sequence found')
+			}
+			if !is_escape_sequence(str[1]) {
+				return error('char literal escape sequence expected, found "${str}"')
+			}
+		} else if str.len != 1 {
+			return error('char literal expected, found "${str}"')
+		}
+	} else if typ == ast.f64_type {
+		if str.count('.') != 1 {
+			return error('f64 literal expected, found "${str}"')
+		}
+	} else if typ == ast.string_type {
+	} else if typ == ast.i64_type {
+		if !str.is_int() {
+			return error('i64 literal expected, found "${str}"')
+		}
+	} else {
+		return error('expected pure literal, found "${str}"')
+	}
+}
+
+@[inline]
+fn is_escape_sequence(c u8) bool {
+	return c in [`x`, `u`, `e`, `n`, `r`, `t`, `v`, `a`, `f`, `b`, `\\`, `\``, `$`, `@`, `?`, `{`,
+		`}`, `'`, `"`, `U`]
+}
+
 fn (mut c Checker) verify_vweb_params_for_method(node ast.Fn) (bool, int, int) {
 	margs := node.params.len - 1 // first arg is the receiver/this
 	// if node.attrs.len == 0 || (node.attrs.len == 1 && node.attrs[0].name == 'post') {
diff --git a/vlib/v/checker/tests/comptime_const/using_comptime_const.vv b/vlib/v/checker/tests/comptime_const/using_comptime_const.vv
deleted file mode 100644
index 29c50f9906c026..00000000000000
--- a/vlib/v/checker/tests/comptime_const/using_comptime_const.vv
+++ /dev/null
@@ -1,15 +0,0 @@
-//#flag -I $const('my_const','some_value')/xyz
-//#include "$const('my_const','some_value')/stdio.h"
-
-const my_int = $compile_value('my_int',4)
-const my_string = $compile_value('my_string','five')
-
-fn main() {
-	println(my_int)
-	println(my_string)
-  int_compile_value := $compile_value('my_const',5)
-	println(int_compile_value)
-  float_compile_value := $compile_value('my_float',1.0)
-  println(float_compile_value)
-	println('done')
-}
diff --git a/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v b/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
new file mode 100644
index 00000000000000..797941922aaabd
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
@@ -0,0 +1,13 @@
+const my_f64 = $compile_value('my_f64', 1.0)
+const my_int = $compile_value('my_int', 2)
+const my_string = $compile_value('my_string', 'three')
+const my_bool = $compile_value('my_bool', false)
+const my_char = $compile_value('my_char', `f`)
+
+fn test_default_compile_values() {
+	assert my_f64 == 1.0
+	assert my_int == 2
+	assert my_string == 'three'
+	assert my_bool == false
+	assert my_char == `f`
+}
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out b/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
new file mode 100644
index 00000000000000..aa2447e5828a08
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
@@ -0,0 +1,3 @@
+vlib/v/checker/tests/comptime_value/parser_errors_1.vv:1:16: error: -cv/-compile-value values can only be pure literals
+    1 | const my_f32 = $compile_value('my_f32', f32(42.0))
+      |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\ No newline at end of file
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_1.vv b/vlib/v/checker/tests/comptime_value/parser_errors_1.vv
new file mode 100644
index 00000000000000..a142be5b2f8853
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/parser_errors_1.vv
@@ -0,0 +1 @@
+const my_f32 = $compile_value('my_f32', f32(42.0))
diff --git a/vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv b/vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
new file mode 100644
index 00000000000000..93457e425343b4
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
@@ -0,0 +1,15 @@
+// This file should pass if compiled/run with:
+// v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+const my_f64 = $compile_value('my_f64', 1.0)
+const my_int = $compile_value('my_int', 2)
+const my_string = $compile_value('my_string', 'three')
+const my_bool = $compile_value('my_bool', false)
+const my_char = $compile_value('my_char', `f`)
+
+fn main() {
+	assert my_f64 == 2.0
+	assert my_int == 3
+	assert my_string == 'a four'
+	assert my_bool == true
+	assert my_char == `g`
+}
diff --git a/vlib/v/checker/tests/comptime_value/using_comptime_value.run.out b/vlib/v/checker/tests/comptime_value/using_comptime_value.run.out
new file mode 100644
index 00000000000000..a172d30507770b
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/using_comptime_value.run.out
@@ -0,0 +1,3 @@
+42.0
+false
+done
\ No newline at end of file
diff --git a/vlib/v/checker/tests/comptime_value/using_comptime_value.vv b/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
new file mode 100644
index 00000000000000..4bf78c73c3b0af
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
@@ -0,0 +1,11 @@
+// TODO: support #flag -I $const('my_flag','flag_value')/xyz
+// TODO: support #include "$const('my_include','/usr/include')/stdio.h"
+
+const my_f64 = $compile_value('my_f64', 42.0)
+
+fn main() {
+  println(my_f64)
+	cv_bool := $compile_value('my_bool', false)
+  println(cv_bool)
+	println('done')
+}
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index e553382e4eab1f..f5439d803e302a 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -2186,6 +2186,15 @@ pub fn (mut f Fmt) comptime_call(node ast.ComptimeCall) {
 					f.write("\$${node.method_name}('${node.args_var}')")
 				}
 			}
+			node.method_name == 'compile_value' {
+				if node.args_var.contains("'") {
+					f.write('\$${node.method_name}("${node.args_var}", ')
+				} else {
+					f.write("\$${node.method_name}('${node.args_var}', ")
+				}
+				f.expr(node.args[0].expr)
+				f.write(')')
+			}
 			node.method_name == 'res' {
 				if node.args_var != '' {
 					f.write('\$res(${node.args_var})')
diff --git a/vlib/v/fmt/tests/comptime_value_keep.vv b/vlib/v/fmt/tests/comptime_value_keep.vv
new file mode 100644
index 00000000000000..2b1dfeca174755
--- /dev/null
+++ b/vlib/v/fmt/tests/comptime_value_keep.vv
@@ -0,0 +1,7 @@
+fn main() {
+	val_str := $compile_value('key_str', 'value')
+	val_f64 := $compile_value('key_f64', 42.0)
+	val_int := $compile_value('key_int', 56)
+	val_bool := $compile_value('key_bool', false)
+	val_char := $compile_value('key_char', `f`)
+}
diff --git a/vlib/v/gen/c/comptime.v b/vlib/v/gen/c/comptime.v
index 0565b8bacf1b86..0e1f477aee090f 100644
--- a/vlib/v/gen/c/comptime.v
+++ b/vlib/v/gen/c/comptime.v
@@ -55,9 +55,10 @@ fn (mut g Gen) comptime_call(mut node ast.ComptimeCall) {
 	if node.method_name == 'compile_value' {
 		// $compile_value('some_string',<default value>)
 		val := util.cescaped_path(node.compile_value)
-		// dump(node)
 		if node.result_type == ast.string_type {
 			g.write('_SLIT("${val}")')
+		} else if node.result_type == ast.char_type {
+			g.write("'${val}'")
 		} else {
 			g.write('${val}')
 		}

From f5bf59c71bf896ae58394a6aec37113e215fa48d Mon Sep 17 00:00:00 2001
From: larpon <768942+larpon@users.noreply.github.com>
Date: Sun, 16 Jun 2024 15:25:16 +0200
Subject: [PATCH 03/25] ci: update .github/workflows/comptime_ci.yml

Co-authored-by: Jose Mendoza  <56417208+StunxFS@users.noreply.github.com>
---
 .github/workflows/comptime_ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/comptime_ci.yml b/.github/workflows/comptime_ci.yml
index 78cc6c3c9d4255..7e626b2c4bb702 100644
--- a/.github/workflows/comptime_ci.yml
+++ b/.github/workflows/comptime_ci.yml
@@ -1,4 +1,4 @@
-name: Time CI
+name: Comptime CI
 
 on:
   push:

From df29e38cb74a97c1da3a7565944173ae05ad0b64 Mon Sep 17 00:00:00 2001
From: larpon <768942+larpon@users.noreply.github.com>
Date: Sun, 16 Jun 2024 15:25:34 +0200
Subject: [PATCH 04/25] ci: update .github/workflows/comptime_ci.yml

Co-authored-by: Jose Mendoza  <56417208+StunxFS@users.noreply.github.com>
---
 .github/workflows/comptime_ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/comptime_ci.yml b/.github/workflows/comptime_ci.yml
index 7e626b2c4bb702..e0392b4db63859 100644
--- a/.github/workflows/comptime_ci.yml
+++ b/.github/workflows/comptime_ci.yml
@@ -39,7 +39,7 @@ jobs:
       - name: Test -compile-value values
         run: ./v -compile-value my_f64=2.0 -compile-value my_int=3 -compile-value my_string="a four" -compile-value my_bool=true -compile-value my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
 
-  test-time-windows:
+  test-comptime-windows:
     runs-on: windows-2019
     steps:
       - uses: actions/checkout@v4

From 6913bb3698ecbca171c865fbc05ea1538685b2fd Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Sun, 16 Jun 2024 17:56:12 +0300
Subject: [PATCH 05/25] remove comptime_ci.yml, move
 use_flag_comptime_values.vv to vlib/v/gen/c/testdata/

---
 .github/workflows/comptime_ci.yml             | 51 -------------------
 .../c/testdata/use_flag_comptime_values.out   |  5 ++
 .../c/testdata}/use_flag_comptime_values.vv   |  7 ++-
 3 files changed, 11 insertions(+), 52 deletions(-)
 delete mode 100644 .github/workflows/comptime_ci.yml
 create mode 100644 vlib/v/gen/c/testdata/use_flag_comptime_values.out
 rename vlib/v/{checker/tests/comptime_value => gen/c/testdata}/use_flag_comptime_values.vv (68%)

diff --git a/.github/workflows/comptime_ci.yml b/.github/workflows/comptime_ci.yml
deleted file mode 100644
index e0392b4db63859..00000000000000
--- a/.github/workflows/comptime_ci.yml
+++ /dev/null
@@ -1,51 +0,0 @@
-name: Comptime CI
-
-on:
-  push:
-    paths:
-      - 'vlib/**'
-      - '**/comptime_ci.yml'
-      - '!**.md'
-  pull_request:
-    paths:
-      - 'vlib/**'
-      - '**/comptime_ci.yml'
-      - '!**.md'
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref == 'refs/heads/master' && github.sha || github.ref }}
-  cancel-in-progress: true
-
-jobs:
-  test-comptime-linux:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - name: Build V
-        run: make
-      - name: Test -cv values
-        run: ./v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
-      - name: Test -compile-value values
-        run: ./v -compile-value my_f64=2.0 -compile-value my_int=3 -compile-value my_string="a four" -compile-value my_bool=true -compile-value my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
-
-  test-comptime-macos:
-    runs-on: macos-14
-    steps:
-      - uses: actions/checkout@v4
-      - name: Build V
-        run: make
-      - name: Test -cv values
-        run: ./v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
-      - name: Test -compile-value values
-        run: ./v -compile-value my_f64=2.0 -compile-value my_int=3 -compile-value my_string="a four" -compile-value my_bool=true -compile-value my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
-
-  test-comptime-windows:
-    runs-on: windows-2019
-    steps:
-      - uses: actions/checkout@v4
-      - name: Build V
-        run: .\make.bat
-      - name: Test -cv values
-        run: ./v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
-      - name: Test -compile-value values
-        run: ./v -compile-value my_f64=2.0 -compile-value my_int=3 -compile-value my_string="a four" -compile-value my_bool=true -compile-value my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
diff --git a/vlib/v/gen/c/testdata/use_flag_comptime_values.out b/vlib/v/gen/c/testdata/use_flag_comptime_values.out
new file mode 100644
index 00000000000000..d343dc6355d107
--- /dev/null
+++ b/vlib/v/gen/c/testdata/use_flag_comptime_values.out
@@ -0,0 +1,5 @@
+2.0
+3
+a four
+true
+g
diff --git a/vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
similarity index 68%
rename from vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
rename to vlib/v/gen/c/testdata/use_flag_comptime_values.vv
index 93457e425343b4..064c5d51816a13 100644
--- a/vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+++ b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
@@ -1,5 +1,5 @@
 // This file should pass if compiled/run with:
-// v -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g run vlib/v/checker/tests/comptime_value/use_flag_comptime_values.vv
+// vtest vflags: -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g
 const my_f64 = $compile_value('my_f64', 1.0)
 const my_int = $compile_value('my_int', 2)
 const my_string = $compile_value('my_string', 'three')
@@ -12,4 +12,9 @@ fn main() {
 	assert my_string == 'a four'
 	assert my_bool == true
 	assert my_char == `g`
+	println(my_f64)
+	println(my_int)
+	println(my_string)
+	println(my_bool)
+	println(rune(my_char))
 }

From ab2f197149cc6c75f9bcca2be9be0c3b77271a36 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Sun, 16 Jun 2024 17:59:17 +0300
Subject: [PATCH 06/25] compile_compile_values -> compile_values, small cleanup
 of the CLI parameter handling code

---
 vlib/v/checker/comptime.v |  2 +-
 vlib/v/pref/pref.v        | 12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/vlib/v/checker/comptime.v b/vlib/v/checker/comptime.v
index 1f855fd429935f..2ca3a65a90e09c 100644
--- a/vlib/v/checker/comptime.v
+++ b/vlib/v/checker/comptime.v
@@ -41,7 +41,7 @@ fn (mut c Checker) comptime_call(mut node ast.ComptimeCall) ast.Type {
 		}
 		typ := arg.expr.get_pure_type()
 		arg_as_string := arg.str().trim('`"\'')
-		value := c.pref.compile_compile_values[node.args_var] or { arg_as_string }
+		value := c.pref.compile_values[node.args_var] or { arg_as_string }
 		validate_type_string_is_pure_literal(typ, value) or {
 			c.error(err.msg(), node.pos)
 			return ast.void_type
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index 76cecb8e95e968..5454a0dd4d52b1 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -193,8 +193,7 @@ pub mut:
 	// -d vfmt and -d another=0 for `$if vfmt { will execute }` and `$if another ? { will NOT get here }`
 	compile_defines     []string // just ['vfmt']
 	compile_defines_all []string // contains both: ['vfmt','another']
-	// -compile_value key=value
-	compile_compile_values map[string]string
+	compile_values      map[string]string // -compile_value key=value
 	//
 	run_args     []string // `v run x.v 1 2 3` => `1 2 3`
 	printfn_list []string // a list of generated function names, whose source should be shown, for debugging
@@ -1179,12 +1178,13 @@ pub fn cc_from_string(s string) CompilerType {
 }
 
 fn (mut prefs Preferences) parse_compile_value(define string) {
-	define_parts := define.split('=')
-	if define_parts.len == 2 {
-		prefs.compile_compile_values[define_parts[0]] = define_parts[1]
+	if !define.contains('=') {
+		eprintln_exit('V error: Define argument value missing for ${define}.')
 		return
 	}
-	eprintln_exit('V error: Define argument value missing for ${define}.')
+	name := define.all_before('=')
+	value := define.all_after_first('=')
+	prefs.compile_values[name] = value
 }
 
 fn (mut prefs Preferences) parse_define(define string) {

From 95a7e90b1f13c35515072c4986b1f3a40799688c Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Sun, 16 Jun 2024 18:02:43 +0300
Subject: [PATCH 07/25] small cleanup of fmt.v

---
 vlib/v/fmt/fmt.v | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index f5439d803e302a..74de6b6d4726ae 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -2187,11 +2187,7 @@ pub fn (mut f Fmt) comptime_call(node ast.ComptimeCall) {
 				}
 			}
 			node.method_name == 'compile_value' {
-				if node.args_var.contains("'") {
-					f.write('\$${node.method_name}("${node.args_var}", ')
-				} else {
-					f.write("\$${node.method_name}('${node.args_var}', ")
-				}
+				f.write("\$compile_value('${node.args_var}', ")
 				f.expr(node.args[0].expr)
 				f.write(')')
 			}

From c4a8028b267d9a1f30c8f20570268934ef956719 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Sun, 16 Jun 2024 19:52:02 +0300
Subject: [PATCH 08/25] pref: save the -cv options to build_options too, so
 that they can be passed down to modules with -usecache, and invalidate the
 build cache

---
 vlib/v/pref/pref.v | 1 +
 1 file changed, 1 insertion(+)

diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index 5454a0dd4d52b1..b424fc562ecad0 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -826,6 +826,7 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 			}
 			'-cv', '-compile-value' {
 				if compile_value := args[i..][1] {
+					res.build_options << '-cv ${compile_value}'
 					res.parse_compile_value(compile_value)
 				}
 				i++

From ce7a17ffeb7230879334464defb2cc986a9a3666 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 17 Jun 2024 16:01:07 +0300
Subject: [PATCH 09/25] support `-d ident=value` in addition to `-d ident`

---
 .../c/testdata/use_flag_comptime_values.vv    |  2 +-
 vlib/v/pref/pref.v                            | 34 ++++++-------------
 2 files changed, 12 insertions(+), 24 deletions(-)

diff --git a/vlib/v/gen/c/testdata/use_flag_comptime_values.vv b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
index 064c5d51816a13..fb71a74e354b4f 100644
--- a/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
+++ b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
@@ -1,5 +1,5 @@
 // This file should pass if compiled/run with:
-// vtest vflags: -cv my_f64=2.0 -cv my_int=3 -cv my_string="a four" -cv my_bool=true -cv my_char=g
+// vtest vflags: -d my_f64=2.0 -d my_int=3 -d my_string="a four" -d my_bool -d my_char=g
 const my_f64 = $compile_value('my_f64', 1.0)
 const my_int = $compile_value('my_int', 2)
 const my_string = $compile_value('my_string', 'three')
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index b424fc562ecad0..71e94c358c9ce8 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -1189,38 +1189,26 @@ fn (mut prefs Preferences) parse_compile_value(define string) {
 }
 
 fn (mut prefs Preferences) parse_define(define string) {
-	define_parts := define.split('=')
-	prefs.diagnose_deprecated_defines(define_parts)
 	if !(prefs.is_debug && define == 'debug') {
 		prefs.build_options << '-d ${define}'
 	}
-	if define_parts.len == 1 {
+	if !define.contains('=') {
+		prefs.compile_values[define] = 'true'
 		prefs.compile_defines << define
 		prefs.compile_defines_all << define
 		return
 	}
-	if define_parts.len == 2 {
-		prefs.compile_defines_all << define_parts[0]
-		match define_parts[1] {
-			'0' {}
-			'1' {
-				prefs.compile_defines << define_parts[0]
-			}
-			else {
-				eprintln_exit(
-					'V error: Unknown define argument value `${define_parts[1]}` for ${define_parts[0]}.' +
-					' Expected `0` or `1`.')
-			}
+	dname := define.all_before('=')
+	dvalue := define.all_after_first('=')
+	prefs.compile_values[dname] = dvalue
+	prefs.compile_defines_all << dname
+	match dvalue {
+		'0' {}
+		'1' {
+			prefs.compile_defines << dname
 		}
-		return
+		else {}
 	}
-	eprintln_exit('V error: Unknown define argument: ${define}. Expected at most one `=`.')
-}
-
-fn (mut prefs Preferences) diagnose_deprecated_defines(define_parts []string) {
-	// if define_parts[0] == 'no_bounds_checking' {
-	// 	eprintln('`-d no_bounds_checking` was deprecated in 2022/10/30. Use `-no-bounds-checking` instead.')
-	// }
 }
 
 pub fn supported_test_runners_list() string {

From 8d9a23eb1b142c60e5941d2c2771a30ccadb37b2 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 17 Jun 2024 21:46:18 +0300
Subject: [PATCH 10/25] use `$d()`, instead of `$compile_value()`

---
 vlib/v/ast/ast.v                                     |  4 ++--
 vlib/v/checker/checker.v                             |  8 ++++----
 vlib/v/checker/comptime.v                            |  5 ++---
 .../comptime_value/default_comptime_values_test.v    | 10 +++++-----
 .../tests/comptime_value/parser_errors_1.run.out     |  6 +++---
 .../checker/tests/comptime_value/parser_errors_1.vv  |  2 +-
 .../tests/comptime_value/using_comptime_value.vv     | 12 ++++++------
 vlib/v/fmt/fmt.v                                     |  4 ++--
 vlib/v/fmt/tests/comptime_value_keep.vv              | 10 +++++-----
 vlib/v/gen/c/comptime.v                              |  5 +++--
 vlib/v/gen/c/testdata/use_flag_comptime_values.vv    | 10 +++++-----
 vlib/v/parser/comptime.v                             |  6 +++---
 vlib/v/pref/pref.v                                   |  9 +--------
 13 files changed, 42 insertions(+), 49 deletions(-)

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 5955f9a05a628a..9f1746b6d4108c 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -1920,8 +1920,8 @@ pub:
 	scope            &Scope = unsafe { nil }
 	is_vweb          bool
 	is_embed         bool // $embed_file(...)
-	is_env           bool // $env(...)
-	is_compile_value bool // $compile_value(...)
+	is_env           bool // $env(...) // TODO: deprecate after $d() is stable
+	is_compile_value bool // $d(...)
 	env_pos          token.Pos
 	is_pkgconfig     bool
 pub mut:
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index a07896f2053dd4..fdd967b5fbe535 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -2428,8 +2428,8 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 				}
 				node.main = env
 			}
-			if flag.contains('\$compile_value(') {
-				c.error('\$compile_value is not supported in ${node.kind} yet', node.pos)
+			if flag.contains('\$d(') {
+				c.error('\$d() is not supported in ${node.kind} yet', node.pos)
 				return
 			}
 			flag_no_comment := flag.all_before('//').trim_space()
@@ -2515,8 +2515,8 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 					return
 				}
 			}
-			if flag.contains('\$compile_value(') {
-				c.error('\$compile_value is not supported in ${node.kind} yet', node.pos)
+			if flag.contains('\$d(') {
+				c.error('\$d() is not supported in ${node.kind} yet', node.pos)
 				return
 			}
 			for deprecated in ['@VMOD', '@VMODULE', '@VPATH', '@VLIB_PATH'] {
diff --git a/vlib/v/checker/comptime.v b/vlib/v/checker/comptime.v
index 2ca3a65a90e09c..1d756689e37f8a 100644
--- a/vlib/v/checker/comptime.v
+++ b/vlib/v/checker/comptime.v
@@ -31,12 +31,11 @@ fn (mut c Checker) comptime_call(mut node ast.ComptimeCall) ast.Type {
 	}
 	if node.is_compile_value {
 		arg := node.args[0] or {
-			c.error('\$compile_value takes two arguments, a string and a primitive literal',
-				node.pos)
+			c.error('\$d() takes two arguments, a string and a primitive literal', node.pos)
 			return ast.void_type
 		}
 		if !arg.expr.is_pure_literal() {
-			c.error('-cv/-compile-value values can only be pure literals', node.pos)
+			c.error('-d values can only be pure literals', node.pos)
 			return ast.void_type
 		}
 		typ := arg.expr.get_pure_type()
diff --git a/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v b/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
index 797941922aaabd..89a65c6df4a830 100644
--- a/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
+++ b/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
@@ -1,8 +1,8 @@
-const my_f64 = $compile_value('my_f64', 1.0)
-const my_int = $compile_value('my_int', 2)
-const my_string = $compile_value('my_string', 'three')
-const my_bool = $compile_value('my_bool', false)
-const my_char = $compile_value('my_char', `f`)
+const my_f64 = $d('my_f64', 1.0)
+const my_int = $d('my_int', 2)
+const my_string = $d('my_string', 'three')
+const my_bool = $d('my_bool', false)
+const my_char = $d('my_char', `f`)
 
 fn test_default_compile_values() {
 	assert my_f64 == 1.0
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out b/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
index aa2447e5828a08..646412c880bc79 100644
--- a/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
+++ b/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
@@ -1,3 +1,3 @@
-vlib/v/checker/tests/comptime_value/parser_errors_1.vv:1:16: error: -cv/-compile-value values can only be pure literals
-    1 | const my_f32 = $compile_value('my_f32', f32(42.0))
-      |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\ No newline at end of file
+vlib/v/checker/tests/comptime_value/parser_errors_1.vv:1:16: error: -d values can only be pure literals
+    1 | const my_f32 = $d('my_f32', f32(42.0))
+      |                ~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_1.vv b/vlib/v/checker/tests/comptime_value/parser_errors_1.vv
index a142be5b2f8853..7e52c4f3b4dcf7 100644
--- a/vlib/v/checker/tests/comptime_value/parser_errors_1.vv
+++ b/vlib/v/checker/tests/comptime_value/parser_errors_1.vv
@@ -1 +1 @@
-const my_f32 = $compile_value('my_f32', f32(42.0))
+const my_f32 = $d('my_f32', f32(42.0))
diff --git a/vlib/v/checker/tests/comptime_value/using_comptime_value.vv b/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
index 4bf78c73c3b0af..de9be77ccf7b22 100644
--- a/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
+++ b/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
@@ -1,11 +1,11 @@
-// TODO: support #flag -I $const('my_flag','flag_value')/xyz
-// TODO: support #include "$const('my_include','/usr/include')/stdio.h"
+// TODO: support #flag -I $d('my_flag','flag_value')/xyz
+// TODO: support #include "$d('my_include','/usr/include')/stdio.h"
 
-const my_f64 = $compile_value('my_f64', 42.0)
+const my_f64 = $d('my_f64', 42.0)
 
 fn main() {
-  println(my_f64)
-	cv_bool := $compile_value('my_bool', false)
-  println(cv_bool)
+	println(my_f64)
+	cv_bool := $d('my_bool', false)
+	println(cv_bool)
 	println('done')
 }
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index 74de6b6d4726ae..c9f85ce8fff4e7 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -2186,8 +2186,8 @@ pub fn (mut f Fmt) comptime_call(node ast.ComptimeCall) {
 					f.write("\$${node.method_name}('${node.args_var}')")
 				}
 			}
-			node.method_name == 'compile_value' {
-				f.write("\$compile_value('${node.args_var}', ")
+			node.method_name == 'd' {
+				f.write("\$d('${node.args_var}', ")
 				f.expr(node.args[0].expr)
 				f.write(')')
 			}
diff --git a/vlib/v/fmt/tests/comptime_value_keep.vv b/vlib/v/fmt/tests/comptime_value_keep.vv
index 2b1dfeca174755..7bb474537bd77e 100644
--- a/vlib/v/fmt/tests/comptime_value_keep.vv
+++ b/vlib/v/fmt/tests/comptime_value_keep.vv
@@ -1,7 +1,7 @@
 fn main() {
-	val_str := $compile_value('key_str', 'value')
-	val_f64 := $compile_value('key_f64', 42.0)
-	val_int := $compile_value('key_int', 56)
-	val_bool := $compile_value('key_bool', false)
-	val_char := $compile_value('key_char', `f`)
+	val_str := $d('key_str', 'value')
+	val_f64 := $d('key_f64', 42.0)
+	val_int := $d('key_int', 56)
+	val_bool := $d('key_bool', false)
+	val_char := $d('key_char', `f`)
 }
diff --git a/vlib/v/gen/c/comptime.v b/vlib/v/gen/c/comptime.v
index 0e1f477aee090f..5902770680ae3f 100644
--- a/vlib/v/gen/c/comptime.v
+++ b/vlib/v/gen/c/comptime.v
@@ -48,12 +48,13 @@ fn (mut g Gen) comptime_call(mut node ast.ComptimeCall) {
 	}
 	if node.method_name == 'env' {
 		// $env('ENV_VAR_NAME')
+		// TODO: deprecate after support for $d() is stable
 		val := util.cescaped_path(os.getenv(node.args_var))
 		g.write('_SLIT("${val}")')
 		return
 	}
-	if node.method_name == 'compile_value' {
-		// $compile_value('some_string',<default value>)
+	if node.method_name == 'd' {
+		// $d('some_string',<default value>), affected by `-d some_string=actual_value`
 		val := util.cescaped_path(node.compile_value)
 		if node.result_type == ast.string_type {
 			g.write('_SLIT("${val}")')
diff --git a/vlib/v/gen/c/testdata/use_flag_comptime_values.vv b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
index fb71a74e354b4f..2d31d2dc451a33 100644
--- a/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
+++ b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
@@ -1,10 +1,10 @@
 // This file should pass if compiled/run with:
 // vtest vflags: -d my_f64=2.0 -d my_int=3 -d my_string="a four" -d my_bool -d my_char=g
-const my_f64 = $compile_value('my_f64', 1.0)
-const my_int = $compile_value('my_int', 2)
-const my_string = $compile_value('my_string', 'three')
-const my_bool = $compile_value('my_bool', false)
-const my_char = $compile_value('my_char', `f`)
+const my_f64 = $d('my_f64', 1.0)
+const my_int = $d('my_int', 2)
+const my_string = $d('my_string', 'three')
+const my_bool = $d('my_bool', false)
+const my_char = $d('my_char', `f`)
 
 fn main() {
 	assert my_f64 == 2.0
diff --git a/vlib/v/parser/comptime.v b/vlib/v/parser/comptime.v
index bf06214406f2f2..367a555e17bf0a 100644
--- a/vlib/v/parser/comptime.v
+++ b/vlib/v/parser/comptime.v
@@ -8,7 +8,7 @@ import v.ast
 import v.token
 
 const supported_comptime_calls = ['html', 'tmpl', 'env', 'embed_file', 'pkgconfig', 'compile_error',
-	'compile_warn', 'compile_value', 'res']
+	'compile_warn', 'd', 'res']
 const comptime_types = ['map', 'array', 'array_dynamic', 'array_fixed', 'int', 'float', 'struct',
 	'interface', 'enum', 'sumtype', 'alias', 'function', 'option', 'string']
 
@@ -106,7 +106,7 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 	}
 	start_pos := p.tok.pos()
 	p.check(.dollar)
-	error_msg := 'only `\$tmpl()`, `\$env()`, `\$embed_file()`, `\$pkgconfig()`, `\$vweb.html()`, `\$compile_error()`, `\$compile_warn()`, `\$compile_value()` and `\$res()` comptime functions are supported right now'
+	error_msg := 'only `\$tmpl()`, `\$env()`, `\$embed_file()`, `\$pkgconfig()`, `\$vweb.html()`, `\$compile_error()`, `\$compile_warn()`, `\$d()` and `\$res()` comptime functions are supported right now'
 	if p.peek_tok.kind == .dot {
 		name := p.check_name() // skip `vweb.html()` TODO
 		if name != 'vweb' && name != 'veb' {
@@ -159,7 +159,7 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 			method_name: method_name
 			pos: start_pos.extend(p.prev_tok.pos())
 		}
-	} else if method_name == 'compile_value' {
+	} else if method_name == 'd' {
 		const_string := p.tok.lit
 		// const_name_pos := p.tok.pos()
 		p.check(.string)
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index 71e94c358c9ce8..9b4e3b0f7afe79 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -193,7 +193,7 @@ pub mut:
 	// -d vfmt and -d another=0 for `$if vfmt { will execute }` and `$if another ? { will NOT get here }`
 	compile_defines     []string // just ['vfmt']
 	compile_defines_all []string // contains both: ['vfmt','another']
-	compile_values      map[string]string // -compile_value key=value
+	compile_values      map[string]string // the map will contain for `-d key=value`: compile_values['key'] = 'value', and for `-d ident`, it will be: compile_values['ident'] = 'true'
 	//
 	run_args     []string // `v run x.v 1 2 3` => `1 2 3`
 	printfn_list []string // a list of generated function names, whose source should be shown, for debugging
@@ -824,13 +824,6 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 				res.build_options << '${arg} "${res.ldflags.trim_space()}"'
 				i++
 			}
-			'-cv', '-compile-value' {
-				if compile_value := args[i..][1] {
-					res.build_options << '-cv ${compile_value}'
-					res.parse_compile_value(compile_value)
-				}
-				i++
-			}
 			'-d', '-define' {
 				if define := args[i..][1] {
 					res.parse_define(define)

From e1be3eb263bd6ebf6da1fd5d5129eaef698ed7b4 Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Tue, 18 Jun 2024 10:44:17 +0200
Subject: [PATCH 11/25] comptime: add simple string support for `$d()` in
 `#flag`,`#include` statements

---
 vlib/v/checker/checker.v                      | 13 ++--
 .../comptime_value/parser_errors_2.run.out    |  1 +
 .../tests/comptime_value/parser_errors_2.vv   |  1 +
 .../comptime_value/using_comptime_value.vv    |  4 +-
 vlib/v/util/util.v                            | 64 +++++++++++++++++++
 5 files changed, 77 insertions(+), 6 deletions(-)
 create mode 100644 vlib/v/checker/tests/comptime_value/parser_errors_2.run.out
 create mode 100644 vlib/v/checker/tests/comptime_value/parser_errors_2.vv

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index fdd967b5fbe535..2021125b98279d 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -2429,8 +2429,11 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 				node.main = env
 			}
 			if flag.contains('\$d(') {
-				c.error('\$d() is not supported in ${node.kind} yet', node.pos)
-				return
+				d := util.resolve_d_value(c.pref.compile_values, flag) or {
+					c.error(err.msg(), node.pos)
+					return
+				}
+				node.main = d
 			}
 			flag_no_comment := flag.all_before('//').trim_space()
 			if node.kind == 'include' || node.kind == 'preinclude' {
@@ -2516,8 +2519,10 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 				}
 			}
 			if flag.contains('\$d(') {
-				c.error('\$d() is not supported in ${node.kind} yet', node.pos)
-				return
+				flag = util.resolve_d_value(c.pref.compile_values, flag) or {
+					c.error(err.msg(), node.pos)
+					return
+				}
 			}
 			for deprecated in ['@VMOD', '@VMODULE', '@VPATH', '@VLIB_PATH'] {
 				if flag.contains(deprecated) {
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_2.run.out b/vlib/v/checker/tests/comptime_value/parser_errors_2.run.out
new file mode 100644
index 00000000000000..dbc4202d57e5c7
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/parser_errors_2.run.out
@@ -0,0 +1 @@
+builder error: Header file "/opt/invalid/include/stdio.h", needed for module `main` was not found. Please install the corresponding development headers.
\ No newline at end of file
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_2.vv b/vlib/v/checker/tests/comptime_value/parser_errors_2.vv
new file mode 100644
index 00000000000000..7557f5d9915573
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value/parser_errors_2.vv
@@ -0,0 +1 @@
+#include "$d('my_include','/opt/invalid/include')/stdio.h"
diff --git a/vlib/v/checker/tests/comptime_value/using_comptime_value.vv b/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
index de9be77ccf7b22..827dc4616d562b 100644
--- a/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
+++ b/vlib/v/checker/tests/comptime_value/using_comptime_value.vv
@@ -1,5 +1,5 @@
-// TODO: support #flag -I $d('my_flag','flag_value')/xyz
-// TODO: support #include "$d('my_include','/usr/include')/stdio.h"
+#flag -I $d('my_flag','flag_value')/xyz
+#include "$d('my_include','/usr/include')/stdio.h"
 
 const my_f64 = $d('my_f64', 42.0)
 
diff --git a/vlib/v/util/util.v b/vlib/v/util/util.v
index eb7f4be57b92f6..9a10bdf85ce4a2 100644
--- a/vlib/v/util/util.v
+++ b/vlib/v/util/util.v
@@ -115,6 +115,70 @@ pub fn resolve_env_value(str string, check_for_presence bool) !string {
 	return rep
 }
 
+// resolve_d_value replaces all occurrences of `$d('ident','value')`
+// in `str` with either the default `'value'` param or a compile value passed via `-d ident=value`.
+pub fn resolve_d_value(compile_values map[string]string, str string) !string {
+	d_sig := "\$d('"
+	at := str.index(d_sig) or {
+		return error('no "${d_sig}' + '...\')" could be found in "${str}".')
+	}
+	mut all_parsed := d_sig
+	mut ch := u8(`.`)
+	mut d_ident := ''
+	mut i := 0
+	for i = at + d_sig.len; i < str.len && ch != `'`; i++ {
+		ch = u8(str[i])
+		all_parsed += ch.ascii_str()
+		if ch.is_letter() || ch.is_digit() || ch == `_` {
+			d_ident += ch.ascii_str()
+		} else {
+			if !(ch == `'`) {
+				if ch == `$` {
+					return error('cannot use string interpolation in compile time \$d() expression')
+				}
+				return error('invalid `\$d` identifier in "${str}", invalid character "${ch.ascii_str()}"')
+			}
+		}
+	}
+	if d_ident == '' {
+		return error('first argument of `\$d` must be a string identifier')
+	}
+
+	// at this point we should have a valid identifier in `d_ident`.
+	// Next we parse out the default string value
+
+	// advance past the `,` and the opening `'` in second argument, or ... eat whatever is there
+	all_parsed += u8(str[i]).ascii_str()
+	i++
+	all_parsed += u8(str[i]).ascii_str()
+	i++
+	// Rinse, repeat for the expected default value string
+	ch = u8(`.`)
+	mut d_default_value := ''
+	for ; i < str.len && ch != `'`; i++ {
+		ch = u8(str[i])
+		all_parsed += ch.ascii_str()
+		if !(ch == `'`) {
+			d_default_value += ch.ascii_str()
+		}
+		if ch == `$` {
+			return error('cannot use string interpolation in compile time \$d() expression')
+		}
+	}
+	if d_default_value == '' {
+		return error('second argument of `\$d` must be a string identifier')
+	}
+	// at this point we have the identifier and the default value.
+	// now we need to resolve which one to use from `compile_values`.
+	d_value := compile_values[d_ident] or { d_default_value }
+	// if more `$d()` calls remains, resolve those as well:
+	rep := str.replace_once(all_parsed + ')', d_value)
+	if rep.contains(d_sig) {
+		return resolve_d_value(compile_values, rep)
+	}
+	return rep
+}
+
 // launch_tool - starts a V tool in a separate process, passing it the `args`.
 // All V tools are located in the cmd/tools folder, in files or folders prefixed by
 // the letter `v`, followed by the tool name, i.e. `cmd/tools/vdoc/` or `cmd/tools/vpm.v`.

From a70006d580df3169012b84bcad36780e78e40827 Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Tue, 18 Jun 2024 11:45:41 +0200
Subject: [PATCH 12/25] docs: document `$d` in `docs.md` and `CHANGELOG.md`

---
 CHANGELOG.md |  5 +++++
 doc/docs.md  | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd9df61a425845..86a5db489bc81b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## V 0.4.7 (NEXT)
+
+#### Improvements in the language
+- comptime: add support for `-d ident=value` and retrieval in code via `$d('ident', <default value>)`.
+
 ## V 0.4.6
 *20 May 2024*
 
diff --git a/doc/docs.md b/doc/docs.md
index 43ff4af722dcd3..f701b7e50aaf8f 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -6120,6 +6120,44 @@ V can bring in values at compile time from environment variables.
 `$env('ENV_VAR')` can also be used in top-level `#flag` and `#include` statements:
 `#flag linux -I $env('JAVA_HOME')/include`.
 
+#### `$d`
+
+```v
+module main
+
+const my_i64 = $d('my_i64', 1024)
+
+fn main() {
+	compile_time_value := $d('my_define', 'V rocks')
+	println(compile_time_value)
+  println(my_i64)
+}
+```
+
+V can bring in values at compile time from `-d ident=value` flag defines.
+If a flag is not provided via the command line, `$d` will return the default value
+provided as the *second* argument.
+
+Supported default values are the following *pure* literals:
+```v
+fn main() {
+	val_str := $d('id_str', 'value') // can be changed by providing `-d id_str="my id"`
+	val_f64 := $d('id_f64', 42.0) // can be changed by providing `-d id_f64=84.0`
+	val_i64 := $d('id_i64', 56) // can be changed by providing `-d id_i64=123`
+	val_bool := $d('id_bool', false) // can be changed by providing `-d id_bool=true`
+	val_char := $d('id_char', `f`) // can be changed by providing `-d id_char=v``
+	println(val_str)
+	println(val_f64)
+	println(val_i64)
+	println(val_bool)
+	println(rune(val_char))
+}
+```
+
+`$d('ident','value')` can also be used in top-level statements like `#flag` and `#include`:
+`#flag linux -I $d('my_include','/usr')/include`. The default value for `$d` when used in these
+statements should be literal `string`s.
+
 #### `$compile_error` and `$compile_warn`
 
 These two comptime functions are very useful for displaying custom errors/warnings during

From 4e68c084624029db79701fe1786d3598a4ca78a9 Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Tue, 18 Jun 2024 11:46:34 +0200
Subject: [PATCH 13/25] tests: use `my_i64` over `my_int` to clearify the
 default value of `$d` is parsed as `i64`

---
 vlib/v/gen/c/testdata/use_flag_comptime_values.vv | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/vlib/v/gen/c/testdata/use_flag_comptime_values.vv b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
index 2d31d2dc451a33..7f17b36879e686 100644
--- a/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
+++ b/vlib/v/gen/c/testdata/use_flag_comptime_values.vv
@@ -1,19 +1,19 @@
 // This file should pass if compiled/run with:
-// vtest vflags: -d my_f64=2.0 -d my_int=3 -d my_string="a four" -d my_bool -d my_char=g
+// vtest vflags: -d my_f64=2.0 -d my_i64=3 -d my_string="a four" -d my_bool -d my_char=g
 const my_f64 = $d('my_f64', 1.0)
-const my_int = $d('my_int', 2)
+const my_i64 = $d('my_i64', 2)
 const my_string = $d('my_string', 'three')
 const my_bool = $d('my_bool', false)
 const my_char = $d('my_char', `f`)
 
 fn main() {
 	assert my_f64 == 2.0
-	assert my_int == 3
+	assert my_i64 == 3
 	assert my_string == 'a four'
 	assert my_bool == true
 	assert my_char == `g`
 	println(my_f64)
-	println(my_int)
+	println(my_i64)
 	println(my_string)
 	println(my_bool)
 	println(rune(my_char))

From 3714382e029837239a9262ab69e42bf27b95645a Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Tue, 18 Jun 2024 11:53:53 +0200
Subject: [PATCH 14/25] tests: use `my_i64` over `my_int` to clearify the
 default value of `$d` is parsed as `i64`

---
 .../tests/comptime_value/default_comptime_values_test.v       | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v b/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
index 89a65c6df4a830..a9927d8969fa56 100644
--- a/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
+++ b/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
@@ -1,12 +1,12 @@
 const my_f64 = $d('my_f64', 1.0)
-const my_int = $d('my_int', 2)
+const my_i64 = $d('my_i64', 2)
 const my_string = $d('my_string', 'three')
 const my_bool = $d('my_bool', false)
 const my_char = $d('my_char', `f`)
 
 fn test_default_compile_values() {
 	assert my_f64 == 1.0
-	assert my_int == 2
+	assert my_i64 == 2
 	assert my_string == 'three'
 	assert my_bool == false
 	assert my_char == `f`

From 2c0d4630eb2597360cbb80ae3d904021d1bed0b2 Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Tue, 18 Jun 2024 12:00:26 +0200
Subject: [PATCH 15/25] docs: fix via 2x`VAUTOFIX=1 ./v check-md doc/docs.md`

---
 doc/docs.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/docs.md b/doc/docs.md
index f701b7e50aaf8f..41dab8dfb01881 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -6130,7 +6130,7 @@ const my_i64 = $d('my_i64', 1024)
 fn main() {
 	compile_time_value := $d('my_define', 'V rocks')
 	println(compile_time_value)
-  println(my_i64)
+	println(my_i64)
 }
 ```
 
@@ -7769,4 +7769,4 @@ Assignment Operators
 +=   -=   *=   /=   %=
 &=   |=   ^=
 >>=  <<=  >>>=
-```
+```
\ No newline at end of file

From 9e61095f65989a2e9979150916707753ad5b788e Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Tue, 18 Jun 2024 13:02:15 +0200
Subject: [PATCH 16/25] docs: add output examples with and without `-d` usage

---
 doc/docs.md | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/doc/docs.md b/doc/docs.md
index 597899cf4a3cb3..62d6378bfe421c 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -6128,12 +6128,24 @@ module main
 const my_i64 = $d('my_i64', 1024)
 
 fn main() {
-	compile_time_value := $d('my_define', 'V rocks')
+	compile_time_value := $d('my_string', 'V')
 	println(compile_time_value)
 	println(my_i64)
 }
 ```
 
+Running the above with `v run .` will output:
+```
+V
+1024
+```
+
+Running the above with `v -d my_i64=4096 -d my_string="V rocks" run .` will output:
+```
+V rocks
+4096
+```
+
 V can bring in values at compile time from `-d ident=value` flag defines.
 If a flag is not provided via the command line, `$d` will return the default value
 provided as the *second* argument.

From ed003d7213bd259218852c3bbfd5f745ad01b97f Mon Sep 17 00:00:00 2001
From: lmp <dev.larpon@gmail.com>
Date: Tue, 18 Jun 2024 13:10:49 +0200
Subject: [PATCH 17/25] docs: remove surplus "`" character

---
 doc/docs.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/docs.md b/doc/docs.md
index 62d6378bfe421c..c7b8df9813c86b 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -6157,7 +6157,7 @@ fn main() {
 	val_f64 := $d('id_f64', 42.0) // can be changed by providing `-d id_f64=84.0`
 	val_i64 := $d('id_i64', 56) // can be changed by providing `-d id_i64=123`
 	val_bool := $d('id_bool', false) // can be changed by providing `-d id_bool=true`
-	val_char := $d('id_char', `f`) // can be changed by providing `-d id_char=v``
+	val_char := $d('id_char', `f`) // can be changed by providing `-d id_char=v`
 	println(val_str)
 	println(val_f64)
 	println(val_i64)

From 187eb649b3f098876eac669917a0dfac9ba59aa5 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 18 Jun 2024 17:27:29 +0300
Subject: [PATCH 18/25] checker,cgen: fix `$if $d(hi, false) {` bug

---
 vlib/v/checker/comptime.v                     |  10 ++
 vlib/v/gen/c/comptime.v                       |  17 ++-
 .../c/testdata/use_flag_comptime_with_if.out  |  44 +++++++
 .../c/testdata/use_flag_comptime_with_if.vv   | 111 ++++++++++++++++++
 4 files changed, 181 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/gen/c/testdata/use_flag_comptime_with_if.out
 create mode 100644 vlib/v/gen/c/testdata/use_flag_comptime_with_if.vv

diff --git a/vlib/v/checker/comptime.v b/vlib/v/checker/comptime.v
index 1d756689e37f8a..c7ba8175725d0a 100644
--- a/vlib/v/checker/comptime.v
+++ b/vlib/v/checker/comptime.v
@@ -1025,6 +1025,16 @@ fn (mut c Checker) comptime_if_branch(mut cond ast.Expr, pos token.Pos) Comptime
 					return .skip
 				}
 				m.run() or { return .skip }
+				return .eval
+			}
+			if cond.is_compile_value {
+				t := c.expr(mut cond)
+				if t != ast.bool_type {
+					c.error('inside \$if, only \$d() expressions that return bool are allowed',
+						cond.pos)
+					return .skip
+				}
+				return .unknown // always fully generate the code for that branch
 			}
 			return .eval
 		}
diff --git a/vlib/v/gen/c/comptime.v b/vlib/v/gen/c/comptime.v
index 5902770680ae3f..ad2786c8a1ded3 100644
--- a/vlib/v/gen/c/comptime.v
+++ b/vlib/v/gen/c/comptime.v
@@ -690,7 +690,22 @@ fn (mut g Gen) comptime_if_cond(cond ast.Expr, pkg_exist bool) (bool, bool) {
 			return true, false
 		}
 		ast.ComptimeCall {
-			g.write('${pkg_exist}')
+			if cond.method_name == 'pkgconfig' {
+				g.write('${pkg_exist}')
+				return true, false
+			}
+			if cond.method_name == 'd' {
+				if cond.result_type == ast.bool_type {
+					if cond.compile_value == 'true' {
+						g.write('1')
+					} else {
+						g.write('0')
+					}
+				} else {
+					g.write('defined(CUSTOM_DEFINE_${cond.args_var})')
+				}
+				return true, false
+			}
 			return true, false
 		}
 		ast.SelectorExpr {
diff --git a/vlib/v/gen/c/testdata/use_flag_comptime_with_if.out b/vlib/v/gen/c/testdata/use_flag_comptime_with_if.out
new file mode 100644
index 00000000000000..a12528a00a8f4a
--- /dev/null
+++ b/vlib/v/gen/c/testdata/use_flag_comptime_with_if.out
@@ -0,0 +1,44 @@
+>>>>> Should be compiled with: `./v -d ddd1=true -d ddd2=false`
+>>>>> Note that ddd3 is not passed *on purpose*, to test the default .
+===========================================================================
+$d(ddd1, false) : true
+$d(ddd1,  true) : true
+------------------------------------------------------------
+Checking $if with default false:
+1 ddd1 is true
+Checking $if with default true:
+2 ddd1 is true
+------------------------------------------------------------
+Checking $if !$d(ddd1) with default false:
+3 !ddd1 is false
+Checking $if !$d() with default  true:
+4 !ddd1 is false
+
+===========================================================================
+$d(ddd2, false) : false
+$d(ddd2,  true) : false
+------------------------------------------------------------
+Checking $if with default false:
+1 ddd2 is false
+Checking $if with default true:
+2 ddd2 is false
+------------------------------------------------------------
+Checking $if !$d() with default false:
+3 !ddd2 is true
+Checking $if !$d() with default  true:
+4 !ddd2 is true
+
+===========================================================================
+$d(ddd3, false) : false
+$d(ddd3,  true) : true
+------------------------------------------------------------
+Checking $if with default false:
+1 ddd3 is false
+Checking $if with default true:
+2 ddd3 is true
+------------------------------------------------------------
+Checking $if !$d() with default false:
+3 !ddd3 is true
+Checking $if !$d() with default  true:
+4 !ddd3 is false
+
diff --git a/vlib/v/gen/c/testdata/use_flag_comptime_with_if.vv b/vlib/v/gen/c/testdata/use_flag_comptime_with_if.vv
new file mode 100644
index 00000000000000..89bb7916d8e151
--- /dev/null
+++ b/vlib/v/gen/c/testdata/use_flag_comptime_with_if.vv
@@ -0,0 +1,111 @@
+// vtest vflags: -d ddd1=true -d ddd2=false
+
+fn main() {
+	println('>>>>> Should be compiled with: `./v -d ddd1=true -d ddd2=false`')
+	println('>>>>> Note that ddd3 is not passed *on purpose*, to test the default .')
+	assert $d('ddd1', false) == true
+	assert $d('ddd2', true) == false
+	assert $d('ddd3', true) == true
+	check_ddd1()
+	check_ddd2()
+	check_ddd3()
+}
+
+fn check_ddd1() {
+	println('===========================================================================')
+	println('\$d(ddd1, false) : ' + $d('ddd1', false).str())
+	println('\$d(ddd1,  true) : ' + $d('ddd1', true).str())
+	println('------------------------------------------------------------')
+	println('Checking \$if with default false:')
+	$if $d('ddd1', false) {
+		println('1 ddd1 is true')
+	} $else {
+		println('1 ddd1 is false')
+	}
+	println('Checking \$if with default true:')
+	$if $d('ddd1', true) {
+		println('2 ddd1 is true')
+	} $else {
+		println('2 ddd1 is false')
+	}
+	println('------------------------------------------------------------')
+	println('Checking \$if !\$d(ddd1) with default false:')
+	$if !$d('ddd1', false) {
+		println('3 !ddd1 is true')
+	} $else {
+		println('3 !ddd1 is false')
+	}
+	println('Checking \$if !\$d() with default  true:')
+	$if !$d('ddd1', true) {
+		println('4 !ddd1 is true')
+	} $else {
+		println('4 !ddd1 is false')
+	}
+	println('')
+}
+
+fn check_ddd2() {
+	println('===========================================================================')
+	println('\$d(ddd2, false) : ' + $d('ddd2', false).str())
+	println('\$d(ddd2,  true) : ' + $d('ddd2', true).str())
+	println('------------------------------------------------------------')
+	println('Checking \$if with default false:')
+	$if $d('ddd2', false) {
+		println('1 ddd2 is true')
+	} $else {
+		println('1 ddd2 is false')
+	}
+	println('Checking \$if with default true:')
+	$if $d('ddd2', true) {
+		println('2 ddd2 is true')
+	} $else {
+		println('2 ddd2 is false')
+	}
+	println('------------------------------------------------------------')
+	println('Checking \$if !\$d() with default false:')
+	$if !$d('ddd2', false) {
+		println('3 !ddd2 is true')
+	} $else {
+		println('3 !ddd2 is false')
+	}
+	println('Checking \$if !\$d() with default  true:')
+	$if !$d('ddd2', true) {
+		println('4 !ddd2 is true')
+	} $else {
+		println('4 !ddd2 is false')
+	}
+	println('')
+}
+
+fn check_ddd3() {
+	println('===========================================================================')
+	println('\$d(ddd3, false) : ' + $d('ddd3', false).str())
+	println('\$d(ddd3,  true) : ' + $d('ddd3', true).str())
+	println('------------------------------------------------------------')
+	println('Checking \$if with default false:')
+	$if $d('ddd3', false) {
+		println('1 ddd3 is true')
+	} $else {
+		println('1 ddd3 is false')
+	}
+	println('Checking \$if with default true:')
+	$if $d('ddd3', true) {
+		println('2 ddd3 is true')
+	} $else {
+		println('2 ddd3 is false')
+	}
+	println('------------------------------------------------------------')
+	println('Checking \$if !\$d() with default false:')
+	$if !$d('ddd3', false) {
+		println('3 !ddd3 is true')
+	} $else {
+		println('3 !ddd3 is false')
+	}
+	println('Checking \$if !\$d() with default  true:')
+	$if !$d('ddd3', true) {
+		println('4 !ddd3 is true')
+	} $else {
+		println('4 !ddd3 is false')
+	}
+	println('')
+}

From a485534e424b7ee06c427bd705160431d2deff82 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 18 Jun 2024 20:14:14 +0300
Subject: [PATCH 19/25] docs: use txt for the operator appendix

---
 doc/docs.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/docs.md b/doc/docs.md
index c7b8df9813c86b..3f041c89d6203f 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -7747,7 +7747,7 @@ See also [V Types](#v-types).
 
 This lists operators for [primitive types](#primitive-types) only.
 
-```v ignore
+```txt
 +    sum                    integers, floats, strings
 -    difference             integers, floats
 *    product                integers, floats

From f19079d707bc67a4cf01863aae5a806150b4a18d Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 18 Jun 2024 20:41:45 +0300
Subject: [PATCH 20/25] docs: describe `$if $d(ident, false) {`, expand the
 existing description a bit

---
 doc/docs.md | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/doc/docs.md b/doc/docs.md
index 3f041c89d6203f..05874f01f00290 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -6122,6 +6122,17 @@ V can bring in values at compile time from environment variables.
 
 #### `$d`
 
+V can bring in values at compile time from `-d ident=value` flag defines, passed on
+the command line to the compiler. You can also pass `-d ident`, which will have the
+same meaning as passing `-d ident=true`.
+
+To get the value in your code, use: `$d('ident', default)`, where `default`
+can be `false` for booleans, `0` or `123` for i64 numbers, `0.0` or `113.0`
+for f64 numbers, `'a string'` for strings.
+
+When a flag is not provided via the command line, `$d()` will return the `default`
+value provided as the *second* argument.
+
 ```v
 module main
 
@@ -6146,11 +6157,7 @@ V rocks
 4096
 ```
 
-V can bring in values at compile time from `-d ident=value` flag defines.
-If a flag is not provided via the command line, `$d` will return the default value
-provided as the *second* argument.
-
-Supported default values are the following *pure* literals:
+Here is an example of how to use the default values, which have to be *pure* literals:
 ```v
 fn main() {
 	val_str := $d('id_str', 'value') // can be changed by providing `-d id_str="my id"`
@@ -6170,6 +6177,10 @@ fn main() {
 `#flag linux -I $d('my_include','/usr')/include`. The default value for `$d` when used in these
 statements should be literal `string`s.
 
+`$d('ident', false)` can also be used inside `$if $d('ident', false) {` statements,
+granting you the ability to selectively turn on/off certain sections of code, at compile
+time, without modifying your source code, or keeping different versions of it.
+
 #### `$compile_error` and `$compile_warn`
 
 These two comptime functions are very useful for displaying custom errors/warnings during

From 82e8d22c40966875937c70a8cecc16c0a8f3e7ab Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 18 Jun 2024 20:46:29 +0300
Subject: [PATCH 21/25] docs: restore `v ignore` for the operator appendix

---
 doc/docs.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/docs.md b/doc/docs.md
index 05874f01f00290..3dfc96fa888549 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -7758,7 +7758,7 @@ See also [V Types](#v-types).
 
 This lists operators for [primitive types](#primitive-types) only.
 
-```txt
+```v ignore
 +    sum                    integers, floats, strings
 -    difference             integers, floats
 *    product                integers, floats

From 27e6fa9024ab223180414f53fc5fdb687fbbc4d9 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 18 Jun 2024 20:48:32 +0300
Subject: [PATCH 22/25] v.util: small cleanup, extract d_sig as a constant

---
 vlib/v/util/util.v | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/vlib/v/util/util.v b/vlib/v/util/util.v
index 9a10bdf85ce4a2..f38c10b02c76ac 100644
--- a/vlib/v/util/util.v
+++ b/vlib/v/util/util.v
@@ -115,18 +115,19 @@ pub fn resolve_env_value(str string, check_for_presence bool) !string {
 	return rep
 }
 
+const d_sig = "\$d('"
+
 // resolve_d_value replaces all occurrences of `$d('ident','value')`
 // in `str` with either the default `'value'` param or a compile value passed via `-d ident=value`.
 pub fn resolve_d_value(compile_values map[string]string, str string) !string {
-	d_sig := "\$d('"
-	at := str.index(d_sig) or {
-		return error('no "${d_sig}' + '...\')" could be found in "${str}".')
+	at := str.index(util.d_sig) or {
+		return error('no "${util.d_sig}' + '...\')" could be found in "${str}".')
 	}
-	mut all_parsed := d_sig
+	mut all_parsed := util.d_sig
 	mut ch := u8(`.`)
 	mut d_ident := ''
 	mut i := 0
-	for i = at + d_sig.len; i < str.len && ch != `'`; i++ {
+	for i = at + util.d_sig.len; i < str.len && ch != `'`; i++ {
 		ch = u8(str[i])
 		all_parsed += ch.ascii_str()
 		if ch.is_letter() || ch.is_digit() || ch == `_` {
@@ -173,7 +174,7 @@ pub fn resolve_d_value(compile_values map[string]string, str string) !string {
 	d_value := compile_values[d_ident] or { d_default_value }
 	// if more `$d()` calls remains, resolve those as well:
 	rep := str.replace_once(all_parsed + ')', d_value)
-	if rep.contains(d_sig) {
+	if rep.contains(util.d_sig) {
 		return resolve_d_value(compile_values, rep)
 	}
 	return rep

From a90f39d2ca145a56b6179f71104be5f75a10e0e9 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 18 Jun 2024 21:27:26 +0300
Subject: [PATCH 23/25] tests: move files to places where they will be used by
 `./v vlib/v/compiler_errors_test.v` and `./v test-self`

---
 vlib/v/checker/tests/comptime_value/parser_errors_1.run.out    | 3 ---
 ...errors_2.run.out => comptime_value_d_in_include_errors.out} | 2 +-
 ...arser_errors_2.vv => comptime_value_d_in_include_errors.vv} | 0
 .../comptime_value_d_values_can_only_be_pure_literals.out      | 3 +++
 ...vv => comptime_value_d_values_can_only_be_pure_literals.vv} | 0
 .../using_comptime_d_value.run.out}                            | 2 +-
 .../using_comptime_value.vv => run/using_comptime_d_value.vv}  | 0
 vlib/v/compiler_errors_test.v                                  | 2 ++
 .../comptime_value_d_default_test.v}                           | 0
 9 files changed, 7 insertions(+), 5 deletions(-)
 delete mode 100644 vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
 rename vlib/v/checker/tests/{comptime_value/parser_errors_2.run.out => comptime_value_d_in_include_errors.out} (83%)
 rename vlib/v/checker/tests/{comptime_value/parser_errors_2.vv => comptime_value_d_in_include_errors.vv} (100%)
 create mode 100644 vlib/v/checker/tests/comptime_value_d_values_can_only_be_pure_literals.out
 rename vlib/v/checker/tests/{comptime_value/parser_errors_1.vv => comptime_value_d_values_can_only_be_pure_literals.vv} (100%)
 rename vlib/v/checker/tests/{comptime_value/using_comptime_value.run.out => run/using_comptime_d_value.run.out} (68%)
 rename vlib/v/checker/tests/{comptime_value/using_comptime_value.vv => run/using_comptime_d_value.vv} (100%)
 rename vlib/v/{checker/tests/comptime_value/default_comptime_values_test.v => tests/comptime_value_d_default_test.v} (100%)

diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out b/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
deleted file mode 100644
index 646412c880bc79..00000000000000
--- a/vlib/v/checker/tests/comptime_value/parser_errors_1.run.out
+++ /dev/null
@@ -1,3 +0,0 @@
-vlib/v/checker/tests/comptime_value/parser_errors_1.vv:1:16: error: -d values can only be pure literals
-    1 | const my_f32 = $d('my_f32', f32(42.0))
-      |                ~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_2.run.out b/vlib/v/checker/tests/comptime_value_d_in_include_errors.out
similarity index 83%
rename from vlib/v/checker/tests/comptime_value/parser_errors_2.run.out
rename to vlib/v/checker/tests/comptime_value_d_in_include_errors.out
index dbc4202d57e5c7..58b4a71ccb2998 100644
--- a/vlib/v/checker/tests/comptime_value/parser_errors_2.run.out
+++ b/vlib/v/checker/tests/comptime_value_d_in_include_errors.out
@@ -1 +1 @@
-builder error: Header file "/opt/invalid/include/stdio.h", needed for module `main` was not found. Please install the corresponding development headers.
\ No newline at end of file
+builder error: Header file "/opt/invalid/include/stdio.h", needed for module `main` was not found. Please install the corresponding development headers.
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_2.vv b/vlib/v/checker/tests/comptime_value_d_in_include_errors.vv
similarity index 100%
rename from vlib/v/checker/tests/comptime_value/parser_errors_2.vv
rename to vlib/v/checker/tests/comptime_value_d_in_include_errors.vv
diff --git a/vlib/v/checker/tests/comptime_value_d_values_can_only_be_pure_literals.out b/vlib/v/checker/tests/comptime_value_d_values_can_only_be_pure_literals.out
new file mode 100644
index 00000000000000..17bb7e081bd1fb
--- /dev/null
+++ b/vlib/v/checker/tests/comptime_value_d_values_can_only_be_pure_literals.out
@@ -0,0 +1,3 @@
+vlib/v/checker/tests/comptime_value_d_values_can_only_be_pure_literals.vv:1:16: error: -d values can only be pure literals
+    1 | const my_f32 = $d('my_f32', f32(42.0))
+      |                ~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/vlib/v/checker/tests/comptime_value/parser_errors_1.vv b/vlib/v/checker/tests/comptime_value_d_values_can_only_be_pure_literals.vv
similarity index 100%
rename from vlib/v/checker/tests/comptime_value/parser_errors_1.vv
rename to vlib/v/checker/tests/comptime_value_d_values_can_only_be_pure_literals.vv
diff --git a/vlib/v/checker/tests/comptime_value/using_comptime_value.run.out b/vlib/v/checker/tests/run/using_comptime_d_value.run.out
similarity index 68%
rename from vlib/v/checker/tests/comptime_value/using_comptime_value.run.out
rename to vlib/v/checker/tests/run/using_comptime_d_value.run.out
index a172d30507770b..d1e104b41f04b1 100644
--- a/vlib/v/checker/tests/comptime_value/using_comptime_value.run.out
+++ b/vlib/v/checker/tests/run/using_comptime_d_value.run.out
@@ -1,3 +1,3 @@
 42.0
 false
-done
\ No newline at end of file
+done
diff --git a/vlib/v/checker/tests/comptime_value/using_comptime_value.vv b/vlib/v/checker/tests/run/using_comptime_d_value.vv
similarity index 100%
rename from vlib/v/checker/tests/comptime_value/using_comptime_value.vv
rename to vlib/v/checker/tests/run/using_comptime_d_value.vv
diff --git a/vlib/v/compiler_errors_test.v b/vlib/v/compiler_errors_test.v
index c5b8e1a5fe59d0..f4dd7ad9ef4676 100644
--- a/vlib/v/compiler_errors_test.v
+++ b/vlib/v/compiler_errors_test.v
@@ -237,6 +237,7 @@ fn (mut tasks Tasks) run() {
 		// cleaner error message, than a generic C error, but without the explanation.
 		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_1.vv'
 		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_with_explanation_2.vv'
+		m_skip_files << 'vlib/v/checker/tests/comptime_value_d_in_include_errors.vv'
 	}
 	$if msvc {
 		m_skip_files << 'vlib/v/checker/tests/asm_alias_does_not_exist.vv'
@@ -244,6 +245,7 @@ fn (mut tasks Tasks) run() {
 		// TODO: investigate why MSVC regressed
 		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_1.vv'
 		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_with_explanation_2.vv'
+		m_skip_files << 'vlib/v/checker/tests/comptime_value_d_in_include_errors.vv'
 	}
 	$if windows {
 		m_skip_files << 'vlib/v/checker/tests/modules/deprecated_module'
diff --git a/vlib/v/checker/tests/comptime_value/default_comptime_values_test.v b/vlib/v/tests/comptime_value_d_default_test.v
similarity index 100%
rename from vlib/v/checker/tests/comptime_value/default_comptime_values_test.v
rename to vlib/v/tests/comptime_value_d_default_test.v

From 1315786e9f59f712132de7d7ad1296a064a6c2cf Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 18 Jun 2024 22:58:41 +0300
Subject: [PATCH 24/25] fix for using_comptime_d_value.vv (include relative to
 the main V project root, instead of /usr/include)

---
 vlib/v/checker/tests/run/using_comptime_d_value.vv | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vlib/v/checker/tests/run/using_comptime_d_value.vv b/vlib/v/checker/tests/run/using_comptime_d_value.vv
index 827dc4616d562b..75725a79420bed 100644
--- a/vlib/v/checker/tests/run/using_comptime_d_value.vv
+++ b/vlib/v/checker/tests/run/using_comptime_d_value.vv
@@ -1,5 +1,5 @@
 #flag -I $d('my_flag','flag_value')/xyz
-#include "$d('my_include','/usr/include')/stdio.h"
+#include "@VMODROOT/$d('my_include','vlib/v')/tests/project_with_c_code/mod1/c/header.h"
 
 const my_f64 = $d('my_f64', 42.0)
 

From be034485114525f593650ae9b042b11a8979e69d Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Wed, 19 Jun 2024 06:22:10 +0300
Subject: [PATCH 25/25] Update vlib/v/util/util.v

Co-authored-by: larpon <768942+larpon@users.noreply.github.com>
---
 vlib/v/util/util.v | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vlib/v/util/util.v b/vlib/v/util/util.v
index f38c10b02c76ac..edd14c1c09758f 100644
--- a/vlib/v/util/util.v
+++ b/vlib/v/util/util.v
@@ -167,7 +167,7 @@ pub fn resolve_d_value(compile_values map[string]string, str string) !string {
 		}
 	}
 	if d_default_value == '' {
-		return error('second argument of `\$d` must be a string identifier')
+		return error('second argument of `\$d` must be a pure literal')
 	}
 	// at this point we have the identifier and the default value.
 	// now we need to resolve which one to use from `compile_values`.