Added ability to report on generic argument mismatch better

Needs some checking over and some tests have altered that need sanity checking, but overall this is starting to get somewhere now.
rust-lang · Feb 25, 2024 · 24599a8 · 24599a8
1 parent bb8b11e
commit 24599a8
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Showing 19 changed files with 649 additions and 83 deletions.
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
@@ -53,7 +53,7 @@ pub use rustc_error_messages::{
     fallback_fluent_bundle, fluent_bundle, DelayDm, DiagnosticMessage, FluentBundle,
     LanguageIdentifier, LazyFallbackBundle, MultiSpan, SpanLabel, SubdiagnosticMessage,
 };
-pub use rustc_lint_defs::{pluralize, Applicability};
+pub use rustc_lint_defs::{a_or_an, display_list_with_comma_and, pluralize, Applicability};
 pub use rustc_span::fatal_error::{FatalError, FatalErrorMarker};
 pub use rustc_span::ErrorGuaranteed;
 pub use snippet::Style;

diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
@@ -1370,6 +1370,11 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow_mut().effect_unification_table().find(var).vid
     }
 
+    /// Check variables are equal
+    pub fn check_ty_vars_equal(&self, a: ty::TyVid, b: ty::TyVid) -> bool {
+        self.inner.borrow_mut().type_variables().check_equal(a, b)
+    }
+
     /// Resolves an int var to a rigid int type, if it was constrained to one,
     /// or else the root int var in the unification table.
     pub fn opportunistic_resolve_int_var(&self, vid: ty::IntVid) -> Ty<'tcx> {

diff --git a/compiler/rustc_infer/src/infer/type_variable.rs b/compiler/rustc_infer/src/infer/type_variable.rs
@@ -284,6 +284,11 @@ impl<'tcx> TypeVariableTable<'_, 'tcx> {
         self.sub_root_var(a) == self.sub_root_var(b)
     }
 
+    /// Returns `true` if `a` and `b` have same "root" (i.e., `a == b`).
+    pub fn check_equal(&mut self, a: ty::TyVid, b: ty::TyVid) -> bool {
+        self.root_var(a) == self.root_var(b)
+    }
+
     /// Retrieves the type to which `vid` has been instantiated, if
     /// any.
     pub fn probe(&mut self, vid: ty::TyVid) -> TypeVariableValue<'tcx> {

diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
@@ -39,6 +39,39 @@ macro_rules! pluralize {
     };
 }
 
+/// Grammatical tool for displaying messages to end users in a nice form.
+///
+/// Returns "an" if the given string starts with a vowel, and "a" otherwise.
+pub fn a_or_an(s: &str) -> &'static str {
+    let mut chars = s.chars();
+    let Some(mut first_alpha_char) = chars.next() else {
+        return "a";
+    };
+    if first_alpha_char == '`' {
+        let Some(next) = chars.next() else {
+            return "a";
+        };
+        first_alpha_char = next;
+    }
+    if ["a", "e", "i", "o", "u", "&"].contains(&&first_alpha_char.to_lowercase().to_string()[..]) {
+        "an"
+    } else {
+        "a"
+    }
+}
+
+/// Grammatical tool for displaying messages to end users in a nice form.
+///
+/// Take a list ["a", "b", "c"] and output a display friendly version "a, b and c"
+pub fn display_list_with_comma_and<T: std::fmt::Display>(v: &[T]) -> String {
+    match v.len() {
+        0 => "".to_string(),
+        1 => v[0].to_string(),
+        2 => format!("{} and {}", v[0], v[1]),
+        _ => format!("{}, {}", v[0], display_list_with_comma_and(&v[1..])),
+    }
+}
+
 /// Indicates the confidence in the correctness of a suggestion.
 ///
 /// All suggestions are marked with an `Applicability`. Tools use the applicability of a suggestion

diff --git a/tests/ui/argument-suggestions/extra_arguments.stderr b/tests/ui/argument-suggestions/extra_arguments.stderr
@@ -45,7 +45,7 @@ note: function defined here
   --> $DIR/extra_arguments.rs:2:4
    |
 LL | fn one_arg<T>(_a: T) {}
-   |    ^^^^^^^    -----
+   |    ^^^^^^^
 
 error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> $DIR/extra_arguments.rs:23:3
@@ -60,7 +60,7 @@ note: function defined here
   --> $DIR/extra_arguments.rs:2:4
    |
 LL | fn one_arg<T>(_a: T) {}
-   |    ^^^^^^^    -----
+   |    ^^^^^^^
 
 error[E0061]: this function takes 1 argument but 3 arguments were supplied
   --> $DIR/extra_arguments.rs:24:3
@@ -74,7 +74,7 @@ note: function defined here
   --> $DIR/extra_arguments.rs:2:4
    |
 LL | fn one_arg<T>(_a: T) {}
-   |    ^^^^^^^    -----
+   |    ^^^^^^^
 help: remove the extra arguments
    |
 LL -   one_arg(1, "", 1.0);
@@ -319,7 +319,7 @@ note: function defined here
   --> $DIR/extra_arguments.rs:2:4
    |
 LL | fn one_arg<T>(_a: T) {}
-   |    ^^^^^^^    -----
+   |    ^^^^^^^
 
 error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> $DIR/extra_arguments.rs:54:3
@@ -334,7 +334,7 @@ note: function defined here
   --> $DIR/extra_arguments.rs:2:4
    |
 LL | fn one_arg<T>(_a: T) {}
-   |    ^^^^^^^    -----
+   |    ^^^^^^^
 
 error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> $DIR/extra_arguments.rs:55:3
@@ -349,7 +349,7 @@ note: function defined here
   --> $DIR/extra_arguments.rs:2:4
    |
 LL | fn one_arg<T>(_a: T) {}
-   |    ^^^^^^^    -----
+   |    ^^^^^^^
 
 error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> $DIR/extra_arguments.rs:60:3
@@ -364,7 +364,7 @@ note: function defined here
   --> $DIR/extra_arguments.rs:2:4
    |
 LL | fn one_arg<T>(_a: T) {}
-   |    ^^^^^^^    -----
+   |    ^^^^^^^
 
 error: aborting due to 22 previous errors
 

diff --git a/tests/ui/argument-suggestions/invalid_arguments.stderr b/tests/ui/argument-suggestions/invalid_arguments.stderr
@@ -24,7 +24,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:6:4
    |
 LL | fn two_arg_same(_a: i32, _b: i32) {}
-   |    ^^^^^^^^^^^^          -------
+   |    ^^^^^^^^^^^^ -------  -------
 
 error[E0308]: mismatched types
   --> $DIR/invalid_arguments.rs:17:16
@@ -38,7 +38,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:6:4
    |
 LL | fn two_arg_same(_a: i32, _b: i32) {}
-   |    ^^^^^^^^^^^^ -------
+   |    ^^^^^^^^^^^^ -------  -------
 
 error[E0308]: arguments to this function are incorrect
   --> $DIR/invalid_arguments.rs:18:3
@@ -66,7 +66,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:7:4
    |
 LL | fn two_arg_diff(_a: i32, _b: f32) {}
-   |    ^^^^^^^^^^^^          -------
+   |    ^^^^^^^^^^^^ -------  -------
 
 error[E0308]: mismatched types
   --> $DIR/invalid_arguments.rs:20:16
@@ -80,7 +80,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:7:4
    |
 LL | fn two_arg_diff(_a: i32, _b: f32) {}
-   |    ^^^^^^^^^^^^ -------
+   |    ^^^^^^^^^^^^ -------  -------
 
 error[E0308]: arguments to this function are incorrect
   --> $DIR/invalid_arguments.rs:21:3
@@ -108,7 +108,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:8:4
    |
 LL | fn three_arg_diff(_a: i32, _b: f32, _c: &str) {}
-   |    ^^^^^^^^^^^^^^ -------
+   |    ^^^^^^^^^^^^^^ -------  -------  --------
 
 error[E0308]: mismatched types
   --> $DIR/invalid_arguments.rs:25:21
@@ -122,7 +122,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:8:4
    |
 LL | fn three_arg_diff(_a: i32, _b: f32, _c: &str) {}
-   |    ^^^^^^^^^^^^^^          -------
+   |    ^^^^^^^^^^^^^^ -------  -------  --------
 
 error[E0308]: mismatched types
   --> $DIR/invalid_arguments.rs:26:26
@@ -136,7 +136,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:8:4
    |
 LL | fn three_arg_diff(_a: i32, _b: f32, _c: &str) {}
-   |    ^^^^^^^^^^^^^^                   --------
+   |    ^^^^^^^^^^^^^^ -------  -------  --------
 
 error[E0308]: arguments to this function are incorrect
   --> $DIR/invalid_arguments.rs:28:3
@@ -207,7 +207,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:9:4
    |
 LL | fn three_arg_repeat(_a: i32, _b: i32, _c: &str) {}
-   |    ^^^^^^^^^^^^^^^^ -------
+   |    ^^^^^^^^^^^^^^^^ -------  -------  --------
 
 error[E0308]: mismatched types
   --> $DIR/invalid_arguments.rs:35:23
@@ -221,7 +221,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:9:4
    |
 LL | fn three_arg_repeat(_a: i32, _b: i32, _c: &str) {}
-   |    ^^^^^^^^^^^^^^^^          -------
+   |    ^^^^^^^^^^^^^^^^ -------  -------  --------
 
 error[E0308]: mismatched types
   --> $DIR/invalid_arguments.rs:36:26
@@ -235,7 +235,7 @@ note: function defined here
   --> $DIR/invalid_arguments.rs:9:4
    |
 LL | fn three_arg_repeat(_a: i32, _b: i32, _c: &str) {}
-   |    ^^^^^^^^^^^^^^^^                   --------
+   |    ^^^^^^^^^^^^^^^^ -------  -------  --------
 
 error[E0308]: arguments to this function are incorrect
   --> $DIR/invalid_arguments.rs:38:3

diff --git a/tests/ui/argument-suggestions/too-long.stderr b/tests/ui/argument-suggestions/too-long.stderr
@@ -11,9 +11,31 @@ note: method defined here
    |
 LL |     fn foo(
    |        ^^^
-...
+LL |         &self,
+LL |         a: i32,
+   |         ------
+LL |         b: i32,
+   |         ------
+LL |         c: i32,
+   |         ------
+LL |         d: i32,
+   |         ------
+LL |         e: i32,
+   |         ------
 LL |         f: i32,
    |         ------
+LL |         g: i32,
+   |         ------
+LL |         h: i32,
+   |         ------
+LL |         i: i32,
+   |         ------
+LL |         j: i32,
+   |         ------
+LL |         k: i32,
+   |         ------
+LL |         l: i32,
+   |         ------
 help: consider dereferencing the borrow
    |
 LL |     qux.foo(a, b, c, d, e, *f, g, h, i, j, k, l);

diff --git a/tests/ui/async-await/coroutine-desc.stderr b/tests/ui/async-await/coroutine-desc.stderr
@@ -5,6 +5,7 @@ LL |     fun(async {}, async {});
    |     --- --------  ^^^^^^^^ expected `async` block, found a different `async` block
    |     |   |
    |     |   the expected `async` block
+   |     |   expected argument `f2` to be an `async` block because that argument needs to match the type of this parameter
    |     arguments to this function are incorrect
    |
    = note: expected `async` block `{async block@$DIR/coroutine-desc.rs:10:9: 10:17}`
@@ -13,14 +14,19 @@ note: function defined here
   --> $DIR/coroutine-desc.rs:8:4
    |
 LL | fn fun<F: Future<Output = ()>>(f1: F, f2: F) {}
-   |    ^^^                                -----
+   |    ^^^ -                       -----  -----
+   |        |                       |      |
+   |        |                       |      this parameter needs to match the `async` block type of `f1`
+   |        |                       `f2` needs to match the type of this parameter
+   |        `f1` and `f2` all reference this parameter F
 
 error[E0308]: mismatched types
   --> $DIR/coroutine-desc.rs:12:16
    |
 LL |     fun(one(), two());
-   |     ---        ^^^^^ expected future, found a different future
-   |     |
+   |     --- -----  ^^^^^ expected future, found a different future
+   |     |   |
+   |     |   expected argument `f2` to be a future because that argument needs to match the type of this parameter
    |     arguments to this function are incorrect
    |
    = help: consider `await`ing on both `Future`s
@@ -29,15 +35,20 @@ note: function defined here
   --> $DIR/coroutine-desc.rs:8:4
    |
 LL | fn fun<F: Future<Output = ()>>(f1: F, f2: F) {}
-   |    ^^^                                -----
+   |    ^^^ -                       -----  -----
+   |        |                       |      |
+   |        |                       |      this parameter needs to match the future type of `f1`
+   |        |                       `f2` needs to match the type of this parameter
+   |        `f1` and `f2` all reference this parameter F
 
 error[E0308]: mismatched types
   --> $DIR/coroutine-desc.rs:14:26
    |
 LL |     fun((async || {})(), (async || {})());
-   |     ---           --     ^^^^^^^^^^^^^^^ expected `async` closure body, found a different `async` closure body
-   |     |             |
-   |     |             the expected `async` closure body
+   |     --- ---------------  ^^^^^^^^^^^^^^^ expected `async` closure body, found a different `async` closure body
+   |     |   |         |
+   |     |   |         the expected `async` closure body
+   |     |   expected argument `f2` to be an `async` closure body because that argument needs to match the type of this parameter
    |     arguments to this function are incorrect
    |
    = note: expected `async` closure body `{async closure body@$DIR/coroutine-desc.rs:14:19: 14:21}`
@@ -46,7 +57,11 @@ note: function defined here
   --> $DIR/coroutine-desc.rs:8:4
    |
 LL | fn fun<F: Future<Output = ()>>(f1: F, f2: F) {}
-   |    ^^^                                -----
+   |    ^^^ -                       -----  -----
+   |        |                       |      |
+   |        |                       |      this parameter needs to match the `async` closure body type of `f1`
+   |        |                       `f2` needs to match the type of this parameter
+   |        `f1` and `f2` all reference this parameter F
 
 error: aborting due to 3 previous errors
 

diff --git a/tests/ui/coercion/coerce-reborrow-multi-arg-fail.stderr b/tests/ui/coercion/coerce-reborrow-multi-arg-fail.stderr
@@ -2,8 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/coerce-reborrow-multi-arg-fail.rs:4:18
    |
 LL |     test(&mut 7, &7);
-   |     ----         ^^ types differ in mutability
-   |     |
+   |     ---- ------  ^^ types differ in mutability
+   |     |    |
+   |     |    expected argument `_b` to be an `&mut {integer}` because that argument needs to match the type of this parameter
    |     arguments to this function are incorrect
    |
    = note: expected mutable reference `&mut {integer}`
@@ -12,7 +13,11 @@ note: function defined here
   --> $DIR/coerce-reborrow-multi-arg-fail.rs:1:4
    |
 LL | fn test<T>(_a: T, _b: T) {}
-   |    ^^^^           -----
+   |    ^^^^ -  -----  -----
+   |         |  |      |
+   |         |  |      this parameter needs to match the `&mut {integer}` type of `_a`
+   |         |  `_b` needs to match the type of this parameter
+   |         `_a` and `_b` all reference this parameter T
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/coercion/coerce-to-bang.stderr b/tests/ui/coercion/coerce-to-bang.stderr
@@ -12,7 +12,7 @@ note: function defined here
   --> $DIR/coerce-to-bang.rs:3:4
    |
 LL | fn foo(x: usize, y: !, z: usize) { }
-   |    ^^^           ----
+   |    ^^^ --------  ----  --------
 
 error[E0308]: mismatched types
   --> $DIR/coerce-to-bang.rs:18:13
@@ -28,7 +28,7 @@ note: function defined here
   --> $DIR/coerce-to-bang.rs:3:4
    |
 LL | fn foo(x: usize, y: !, z: usize) { }
-   |    ^^^           ----
+   |    ^^^ --------  ----  --------
 
 error[E0308]: mismatched types
   --> $DIR/coerce-to-bang.rs:26:12
@@ -44,7 +44,7 @@ note: function defined here
   --> $DIR/coerce-to-bang.rs:3:4
    |
 LL | fn foo(x: usize, y: !, z: usize) { }
-   |    ^^^           ----
+   |    ^^^ --------  ----  --------
 
 error[E0308]: mismatched types
   --> $DIR/coerce-to-bang.rs:36:12
@@ -60,7 +60,7 @@ note: function defined here
   --> $DIR/coerce-to-bang.rs:3:4
    |
 LL | fn foo(x: usize, y: !, z: usize) { }
-   |    ^^^           ----
+   |    ^^^ --------  ----  --------
 
 error[E0308]: mismatched types
   --> $DIR/coerce-to-bang.rs:45:12
@@ -76,7 +76,7 @@ note: function defined here
   --> $DIR/coerce-to-bang.rs:3:4
    |
 LL | fn foo(x: usize, y: !, z: usize) { }
-   |    ^^^           ----
+   |    ^^^ --------  ----  --------
 
 error[E0308]: mismatched types
   --> $DIR/coerce-to-bang.rs:50:21