Account for let foo = expr; to suggest const foo: Ty = expr;

rust-lang · Jul 11, 2024 · cbe7548 · cbe7548
1 parent b56dc8e
commit cbe7548
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Showing 13 changed files with 85 additions and 56 deletions.
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
@@ -819,7 819,12 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
  ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
  self.dcx().create_err(errs::CannotCaptureDynamicEnvironmentInFnItem { span })
  }
- ResolutionError::AttemptToUseNonConstantValueInConstant(ident, suggestion, current) => {
  ResolutionError::AttemptToUseNonConstantValueInConstant {
  ident,
  suggestion,
  current,
  type_span,
  } => {
  // let foo =...
  // ^^^ given this Span
  // ------- get this Span to have an applicable suggestion
@@ -844,6 849,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
  span: sp,
  suggestion,
  current,
  type_span,
  }), Some(errs::AttemptToUseNonConstantValueInConstantLabelWithSuggestion {span})),
  None,
  )

diff --git a/compiler/rustc_resolve/src/errors.rs b/compiler/rustc_resolve/src/errors.rs
@@ -240,16 240,18 @@ pub(crate) struct AttemptToUseNonConstantValueInConstant<'a> {
 }
 
 #[derive(Subdiagnostic)]
-#[suggestion(
 #[multipart_suggestion(
  resolve_attempt_to_use_non_constant_value_in_constant_with_suggestion,
- code = "{suggestion} ",
  style = "verbose",
- applicability = "maybe-incorrect"
  applicability = "has-placeholders"
 )]
 pub(crate) struct AttemptToUseNonConstantValueInConstantWithSuggestion<'a> {
- #[primary_span]
  // #[primary_span]
  #[suggestion_part(code = "{suggestion} ")]
  pub(crate) span: Span,
  pub(crate) suggestion: &'a str,
  #[suggestion_part(code = ": /* Type */")]
  pub(crate) type_span: Option<Span>,
  pub(crate) current: &'a str,
 }
 

diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs
@@ -1178,21 1178,41 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
  if let Some(span) = finalize {
  let (span, resolution_error) = match item {
  None if rib_ident.as_str() == "self" => (span, LowercaseSelf),
- None => (
- rib_ident.span,
- AttemptToUseNonConstantValueInConstant(
- original_rib_ident_def,
- "const",
- "let",
- ),
- ),
  None => {
  // If we have a `let name = expr;`, we have the span for
  // `name` and use that to see if it is followed by a type
  // specifier. If not, then we know we need to suggest
  // `const name: Ty = expr;`. This is a heuristic, it will
  // break down in the presence of macros.
  let sm = self.tcx.sess.source_map();
  let type_span = match sm.span_look_ahead(
  original_rib_ident_def.span,
  ":",
  None,
  ) {
  None => {
  Some(original_rib_ident_def.span.shrink_to_hi())
  }
  Some(_) => None,
  };
  (
  rib_ident.span,
  AttemptToUseNonConstantValueInConstant {
  ident: original_rib_ident_def,
  suggestion: "const",
  current: "let",
  type_span,
  },
  )
  }
  Some((ident, kind)) => (
  span,
- AttemptToUseNonConstantValueInConstant(
  AttemptToUseNonConstantValueInConstant {
  ident,
- "let",
- kind.as_str(),
- ),
  suggestion: "let",
  current: kind.as_str(),
  type_span: None,
  },
  ),
  };
  self.report_error(span, resolution_error);

diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
@@ -236,11 236,12 @@ enum ResolutionError<'a> {
  /// Error E0434: can't capture dynamic environment in a fn item.
  CannotCaptureDynamicEnvironmentInFnItem,
  /// Error E0435: attempt to use a non-constant value in a constant.
- AttemptToUseNonConstantValueInConstant(
- Ident,
- /* suggestion */ &'static str,
- /* current */ &'static str,
- ),
  AttemptToUseNonConstantValueInConstant {
  ident: Ident,
  suggestion: &'static str,
  current: &'static str,
  type_span: Option<Span>,
  },
  /// Error E0530: `X` bindings cannot shadow `Y`s.
  BindingShadowsSomethingUnacceptable {
  shadowing_binding: PatternSource,

diff --git a/tests/ui/asm/parse-error.stderr b/tests/ui/asm/parse-error.stderr
@@ -376,8 376,8 @@ LL | asm!("{}", options(), const foo);
  |
 help: consider using `const` instead of `let`
  |
-LL | const foo = 0;
- | ~~~~~
 LL | const foo: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/parse-error.rs:71:44
@@ -387,8 387,8 @@ LL | asm!("{}", clobber_abi("C"), const foo);
  |
 help: consider using `const` instead of `let`
  |
-LL | const foo = 0;
- | ~~~~~
 LL | const foo: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/parse-error.rs:74:55
@@ -398,8 398,8 @@ LL | asm!("{}", options(), clobber_abi("C"), const foo);
  |
 help: consider using `const` instead of `let`
  |
-LL | const foo = 0;
- | ~~~~~
 LL | const foo: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/parse-error.rs:76:31
@@ -409,8 409,8 @@ LL | asm!("{a}", a = const foo, a = const bar);
  |
 help: consider using `const` instead of `let`
  |
-LL | const foo = 0;
- | ~~~~~
 LL | const foo: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/parse-error.rs:76:46
@@ -420,8 420,8 @@ LL | asm!("{a}", a = const foo, a = const bar);
  |
 help: consider using `const` instead of `let`
  |
-LL | const bar = 0;
- | ~~~~~
 LL | const bar: /* Type */ = 0;
  | ~~~~~ 
 
 error: aborting due to 64 previous errors
 

diff --git a/tests/ui/asm/type-check-1.stderr b/tests/ui/asm/type-check-1.stderr
@@ -6,8 6,8 @@ LL | asm!("{}", const x);
  |
 help: consider using `const` instead of `let`
  |
-LL | const x = 0;
- | ~~~~~
 LL | const x: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/type-check-1.rs:44:36
@@ -17,8 17,8 @@ LL | asm!("{}", const const_foo(x));
  |
 help: consider using `const` instead of `let`
  |
-LL | const x = 0;
- | ~~~~~
 LL | const x: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/type-check-1.rs:47:36
@@ -28,8 28,8 @@ LL | asm!("{}", const const_bar(x));
  |
 help: consider using `const` instead of `let`
  |
-LL | const x = 0;
- | ~~~~~
 LL | const x: /* Type */ = 0;
  | ~~~~~ 
 
 error: invalid `sym` operand
  --> $DIR/type-check-1.rs:49:24

diff --git a/tests/ui/asm/x86_64/x86_64_parse_error.stderr b/tests/ui/asm/x86_64/x86_64_parse_error.stderr
@@ -20,8 20,8 @@ LL | asm!("{a}", in("eax") foo, a = const bar);
  |
 help: consider using `const` instead of `let`
  |
-LL | const bar = 0;
- | ~~~~~
 LL | const bar: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/x86_64_parse_error.rs:15:46
@@ -31,8 31,8 @@ LL | asm!("{a}", in("eax") foo, a = const bar);
  |
 help: consider using `const` instead of `let`
  |
-LL | const bar = 0;
- | ~~~~~
 LL | const bar: /* Type */ = 0;
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/x86_64_parse_error.rs:17:42
@@ -42,8 42,8 @@ LL | asm!("{1}", in("eax") foo, const bar);
  |
 help: consider using `const` instead of `let`
  |
-LL | const bar = 0;
- | ~~~~~
 LL | const bar: /* Type */ = 0;
  | ~~~~~ 
 
 error: aborting due to 5 previous errors
 

diff --git a/tests/ui/const-generics/legacy-const-generics-bad.stderr b/tests/ui/const-generics/legacy-const-generics-bad.stderr
@@ -6,8 6,8 @@ LL | legacy_const_generics::foo(0, a, 2);
  |
 help: consider using `const` instead of `let`
  |
-LL | const a = 1;
- | ~~~~~
 LL | const a: /* Type */ = 1;
  | ~~~~~ 
 
 error: generic parameters may not be used in const operations
  --> $DIR/legacy-const-generics-bad.rs:12:35

diff --git a/tests/ui/consts/non-const-value-in-const.stderr b/tests/ui/consts/non-const-value-in-const.stderr
@@ -17,8 17,8 @@ LL | let _ = [0; x];
  |
 help: consider using `const` instead of `let`
  |
-LL | const x = 5;
- | ~~~~~
 LL | const x: /* Type */ = 5;
  | ~~~~~ 
 
 error: aborting due to 2 previous errors
 

diff --git a/tests/ui/issues/issue-27433.fixed b/tests/ui/issues/issue-27433.fixed
@@ -3,5 3,5 @@ fn main() {
  let foo = 42u32;
  #[allow(unused_variables, non_snake_case)]
  let FOO : u32 = foo;
-  //~^ ERROR attempt to use a non-constant value in a constant
  //~^ ERROR attempt to use a non-constant value in a constant
 }
diff --git a/tests/ui/issues/issue-27433.rs b/tests/ui/issues/issue-27433.rs
@@ -3,5 3,5 @@ fn main() {
  let foo = 42u32;
  #[allow(unused_variables, non_snake_case)]
  const FOO : u32 = foo;
-  //~^ ERROR attempt to use a non-constant value in a constant
  //~^ ERROR attempt to use a non-constant value in a constant
 }
diff --git a/tests/ui/repeat-expr/repeat_count.stderr b/tests/ui/repeat-expr/repeat_count.stderr
@@ -6,8 6,8 @@ LL | let a = [0; n];
  |
 help: consider using `const` instead of `let`
  |
-LL | const n = 1;
- | ~~~~~
 LL | const n: /* Type */ = 1;
  | ~~~~~ 
 
 error[E0308]: mismatched types
  --> $DIR/repeat_count.rs:7:17

diff --git a/tests/ui/typeof/issue-42060.stderr b/tests/ui/typeof/issue-42060.stderr
@@ -6,8 6,8 @@ LL | let other: typeof(thing) = thing;
  |
 help: consider using `const` instead of `let`
  |
-LL | const thing = ();
- | ~~~~~
 LL | const thing: /* Type */ = ();
  | ~~~~~ 
 
 error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/issue-42060.rs:9:13
@@ -17,8 17,8 @@ LL | <typeof(q)>::N
  |
 help: consider using `const` instead of `let`
  |
-LL | const q = 1;
- | ~~~~~
 LL | const q: /* Type */ = 1;
  | ~~~~~ 
 
 error[E0516]: `typeof` is a reserved keyword but unimplemented
  --> $DIR/issue-42060.rs:3:16