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Account for let foo = expr; to suggest const foo: Ty = expr;
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estebank committed Jul 11, 2024
1 parent b56dc8e commit cbe7548
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Showing 13 changed files with 85 additions and 56 deletions.
8 changes: 7 additions & 1 deletion compiler/rustc_resolve/src/diagnostics.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -844,6 +849,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
span: sp,
suggestion,
current,
type_span,
}), Some(errs::AttemptToUseNonConstantValueInConstantLabelWithSuggestion {span})),
None,
)
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10 changes: 6 additions & 4 deletions compiler/rustc_resolve/src/errors.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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,
}

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44 changes: 32 additions & 12 deletions compiler/rustc_resolve/src/ident.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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);
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11 changes: 6 additions & 5 deletions compiler/rustc_resolve/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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,
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20 changes: 10 additions & 10 deletions tests/ui/asm/parse-error.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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

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12 changes: 6 additions & 6 deletions tests/ui/asm/type-check-1.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
Expand All @@ -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
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12 changes: 6 additions & 6 deletions tests/ui/asm/x86_64/x86_64_parse_error.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
Expand All @@ -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

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4 changes: 2 additions & 2 deletions tests/ui/const-generics/legacy-const-generics-bad.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
4 changes: 2 additions & 2 deletions tests/ui/consts/non-const-value-in-const.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -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

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2 changes: 1 addition & 1 deletion tests/ui/issues/issue-27433.fixed
Original file line number Diff line number Diff line change
Expand Up @@ -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
}
2 changes: 1 addition & 1 deletion tests/ui/issues/issue-27433.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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
}
4 changes: 2 additions & 2 deletions tests/ui/repeat-expr/repeat_count.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -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
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8 changes: 4 additions & 4 deletions tests/ui/typeof/issue-42060.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
Expand Down

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