cgen: fix codegen for array fixed on if and match expr (fix #23577, fix

#23589) (#23682)

vlib/v/gen/c/assign.v

@@ -526,7 +526,13 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 				} else {
 					g.write('{${styp} _ = ')
 				}
-				g.expr(val)
+				if val in [ast.MatchExpr, ast.IfExpr] && unaliased_right_sym.info is ast.ArrayFixed {
+					tmp_var := g.expr_with_var(val, var_type, false)
+					g.fixed_array_var_init(tmp_var, false, unaliased_right_sym.info.elem_type,
+						unaliased_right_sym.info.size)
+				} else {
+					g.expr(val)
+				}
 				g.writeln(';}')
 			}
 		} else if node.op == .assign && !g.pref.translated && (is_fixed_array_init
@@ -911,6 +917,11 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 							g.array_init(val, c_name(ident.name))
 						} else if val_type.has_flag(.shared_f) {
 							g.expr_with_cast(val, val_type, var_type)
+						} else if val in [ast.MatchExpr, ast.IfExpr]
+							&& unaliased_right_sym.info is ast.ArrayFixed {
+							tmp_var := g.expr_with_var(val, var_type, false)
+							g.fixed_array_var_init(tmp_var, false, unaliased_right_sym.info.elem_type,
+								unaliased_right_sym.info.size)
 						} else {
 							g.expr(val)
 						}

vlib/v/gen/c/cgen.v

@@ -2114,18 +2114,33 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) bool {
 					g.stmt(stmt)
 				}
 			} else {
+				mut is_array_fixed_init := false
+				mut ret_type := ast.void_type
+
 				g.set_current_pos_as_last_stmt_pos()
 				g.skip_stmt_pos = true
 				mut is_noreturn := false
 				if stmt in [ast.Return, ast.BranchStmt] {
 					is_noreturn = true
 				} else if stmt is ast.ExprStmt {
 					is_noreturn = is_noreturn_callexpr(stmt.expr)
+					if stmt.expr is ast.ArrayInit && stmt.expr.is_fixed {
+						is_array_fixed_init = true
+						ret_type = stmt.expr.typ
+					}
 				}
 				if !is_noreturn {
-					g.write('${tmp_var} = ')
+					if is_array_fixed_init {
+						g.write('memcpy(${tmp_var}, (${g.styp(ret_type)})')
+					} else {
+						g.write('${tmp_var} = ')
+					}
 				}
 				g.stmt(stmt)
+				if is_array_fixed_init {
+					lines := g.go_before_last_stmt().trim_right('; \n')
+					g.writeln('${lines}, sizeof(${tmp_var}));')
+				}
 				if !g.out.last_n(2).contains(';') {
 					g.writeln(';')
 				}

vlib/v/gen/c/if.v

@@ -20,6 +20,9 @@ fn (mut g Gen) need_tmp_var_in_if(node ast.IfExpr) bool {
 			if branch.stmts.len == 1 {
 				if branch.stmts[0] is ast.ExprStmt {
 					stmt := branch.stmts[0] as ast.ExprStmt
+					if stmt.expr is ast.ArrayInit && stmt.expr.is_fixed {
+						return true
+					}
 					if g.need_tmp_var_in_expr(stmt.expr) {
 						return true
 					}

vlib/v/gen/c/match.v

@@ -25,6 +25,9 @@ fn (mut g Gen) need_tmp_var_in_match(node ast.MatchExpr) bool {
 			if branch.stmts.len == 1 {
 				if branch.stmts[0] is ast.ExprStmt {
 					stmt := branch.stmts[0] as ast.ExprStmt
+					if stmt.expr is ast.ArrayInit && stmt.expr.is_fixed {
+						return true
+					}
 					if g.need_tmp_var_in_expr(stmt.expr) {
 						return true
 					}

vlib/v/tests/array_fixed_ternary_test.v

@@ -0,0 +1,28 @@
+fn test_main() {
+	_ := if true { [0]! } else { [1]! }
+	_ := if true { [0] } else { [1] }
+
+	a := if true { [0]! } else { [1]! }
+	b := if true { [0] } else { [1] }
+	assert a.str() == '[0]'
+	assert b.str() == '[0]'
+}
+
+fn test_match() {
+	grid_size := 1
+
+	_ := match grid_size {
+		3 { ['Small', '3x3']! }
+		4 { ['Classic', '4x4']! }
+		5 { ['Big', '5x5']! }
+		else { ['Large', '6x6']! }
+	}
+
+	w := match grid_size {
+		3 { ['Small', '3x3']! }
+		4 { ['Classic', '4x4']! }
+		5 { ['Big', '5x5']! }
+		else { ['Large', '6x6']! }
+	}
+	assert w.str() == "['Large', '6x6']"
+}