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diagnostics: fix let x: vec![] suggestion pointing into stdlib #158934

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diagnostics: fix let x: vec![] suggestion pointing into stdlib #158934

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54 changes: 36 additions & 18 deletions compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3290,18 +3290,18 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
.next()
{
// `let x: S::new(valid_in_ty_ctxt);` -> `let x = S::new(valid_in_ty_ctxt);`
let err = tcx
.dcx()
.struct_span_err(
hir_ty.span,
"expected type, found associated function call",
)
.with_span_suggestion_verbose(
stmt.pat.span.between(hir_ty.span),
let mut err = tcx.dcx().struct_span_err(
hir_ty.span,
"expected type, found associated function call",
);
if let Some(between) = eq_ctxt_suggestion_span(stmt.pat.span, hir_ty.span) {
err.span_suggestion_verbose(
between,
"use `=` if you meant to assign",
" = ".to_string(),
" = ",
Applicability::MaybeIncorrect,
);
}
self.dcx().try_steal_replace_and_emit_err(
hir_ty.span,
StashKey::ReturnTypeNotation,
Expand All @@ -3316,18 +3316,18 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
{
// `let x: i32::something(valid_in_ty_ctxt);` -> `let x = i32::something(valid_in_ty_ctxt);`
// FIXME: Check that `something` is a valid function in `i32`.
let err = tcx
.dcx()
.struct_span_err(
hir_ty.span,
"expected type, found associated function call",
)
.with_span_suggestion_verbose(
stmt.pat.span.between(hir_ty.span),
let mut err = tcx.dcx().struct_span_err(
hir_ty.span,
"expected type, found associated function call",
);
if let Some(between) = eq_ctxt_suggestion_span(stmt.pat.span, hir_ty.span) {
err.span_suggestion_verbose(
between,
"use `=` if you meant to assign",
" = ".to_string(),
" = ",
Applicability::MaybeIncorrect,
);
}
self.dcx().try_steal_replace_and_emit_err(
hir_ty.span,
StashKey::ReturnTypeNotation,
Expand Down Expand Up @@ -3813,3 +3813,21 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
ty::Const::new_value(tcx, valtree, adt_ty)
}
}

/// Computes the `pat.between(ty)` span for the "use `=`" suggestion on `let pat: ty`.
/// Returns `None` if `pat` and `ty` are in incompatible macro contexts (e.g. `pat` is a
/// metavariable from the call site while `ty` lives in the macro body), in which case no
/// suggestion is emitted.
fn eq_ctxt_suggestion_span(pat: Span, ty: Span) -> Option<Span> {
if let Some(ty2) = ty.find_ancestor_in_same_ctxt(pat)
&& pat.hi() <= ty2.lo()
{
return Some(pat.between(ty2));
}
if let Some(pat2) = pat.find_ancestor_in_same_ctxt(ty)
&& pat2.hi() <= ty.lo()
{
return Some(pat2.between(ty));
}
None
}
11 changes: 11 additions & 0 deletions tests/ui/suggestions/let-binding-init-expr-as-ty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,17 @@ fn main() {
//~^ ERROR return type notation is experimental
let x: S::new(()); //~ ERROR expected type, found associated function call

// Macros — suggestion must point at user code, not the macro definition (#158834)
let x: vec![]; //~ ERROR expected type, found associated function call

// When the `let` is inside a macro, no suggestion should be emitted at the call site
macro_rules! make {
($pat:pat) => {
let $pat: Vec::new(); //~ ERROR expected type, found associated function call
};
}
make!(_);

// Literals
let x: 42; //~ ERROR expected type, found `42`
let x: ""; //~ ERROR expected type, found `""`
Expand Down
35 changes: 29 additions & 6 deletions tests/ui/suggestions/let-binding-init-expr-as-ty.stderr
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: expected type, found `42`
--> $DIR/let-binding-init-expr-as-ty.rs:32:12
--> $DIR/let-binding-init-expr-as-ty.rs:43:12
|
LL | let x: 42;
| - ^^ expected type
Expand All @@ -13,7 +13,7 @@ LL + let x = 42;
|

error: expected type, found `""`
--> $DIR/let-binding-init-expr-as-ty.rs:33:12
--> $DIR/let-binding-init-expr-as-ty.rs:44:12
|
LL | let x: "";
| - ^^ expected type
Expand All @@ -39,7 +39,7 @@ LL + let foo = i32::from_be(num);
|

error[E0573]: expected type, found function `bar`
--> $DIR/let-binding-init-expr-as-ty.rs:36:12
--> $DIR/let-binding-init-expr-as-ty.rs:47:12
|
LL | let x: bar();
| ^^^^^ not a type
Expand All @@ -51,13 +51,13 @@ LL + let x = bar();
|

error[E0573]: expected type, found function `bar`
--> $DIR/let-binding-init-expr-as-ty.rs:37:12
--> $DIR/let-binding-init-expr-as-ty.rs:48:12
|
LL | let x: bar;
| ^^^ not a type

error[E0573]: expected type, found local variable `x`
--> $DIR/let-binding-init-expr-as-ty.rs:40:12
--> $DIR/let-binding-init-expr-as-ty.rs:51:12
|
LL | struct K(S::new(()));
| --------------------- similarly named struct `K` defined here
Expand Down Expand Up @@ -153,7 +153,30 @@ LL - let x: S::new(());
LL + let x = S::new(());
|

error: aborting due to 13 previous errors
error: expected type, found associated function call
--> $DIR/let-binding-init-expr-as-ty.rs:32:12
|
LL | let x: vec![];
| ^^^^^^
|
help: use `=` if you meant to assign
|
LL - let x: vec![];
LL + let x = vec![];
|

error: expected type, found associated function call
--> $DIR/let-binding-init-expr-as-ty.rs:37:23
|
LL | let $pat: Vec::new();
| ^^^^^^^^^^
...
LL | make!(_);
| -------- in this macro invocation
|
= note: this error originates in the macro `make` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 15 previous errors

Some errors have detailed explanations: E0573, E0658.
For more information about an error, try `rustc --explain E0573`.
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