diff options
4 files changed, 77 insertions, 11 deletions
diff --git a/compiler/rustc_hir_typeck/src/demand.rs b/compiler/rustc_hir_typeck/src/demand.rs index be618eb664c..9ca7730daa6 100644 --- a/compiler/rustc_hir_typeck/src/demand.rs +++ b/compiler/rustc_hir_typeck/src/demand.rs @@ -30,6 +30,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, error: Option<TypeError<'tcx>>, ) { + if expr_ty == expected { + return; + } + self.annotate_expected_due_to_let_ty(err, expr, error); // Use `||` to give these suggestions a precedence diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs index a7a60a19bd3..8cf70eb5431 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs @@ -597,6 +597,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } }; + let mk_trace = |span, (formal_ty, expected_ty), provided_ty| { + let mismatched_ty = if expected_ty == provided_ty { + // If expected == provided, then we must have failed to sup + // the formal type. Avoid printing out "expected Ty, found Ty" + // in that case. + formal_ty + } else { + expected_ty + }; + TypeTrace::types(&self.misc(span), true, mismatched_ty, provided_ty) + }; + // The algorithm here is inspired by levenshtein distance and longest common subsequence. // We'll try to detect 4 different types of mistakes: // - An extra parameter has been provided that doesn't satisfy *any* of the other inputs @@ -661,10 +673,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // A tuple wrap suggestion actually occurs within, // so don't do anything special here. err = self.err_ctxt().report_and_explain_type_error( - TypeTrace::types( - &self.misc(*lo), - true, - formal_and_expected_inputs[mismatch_idx.into()].1, + mk_trace( + *lo, + formal_and_expected_inputs[mismatch_idx.into()], provided_arg_tys[mismatch_idx.into()].0, ), terr, @@ -748,9 +759,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { errors.drain_filter(|error| { let Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(Some(e))) = error else { return false }; let (provided_ty, provided_span) = provided_arg_tys[*provided_idx]; - let (expected_ty, _) = formal_and_expected_inputs[*expected_idx]; - let cause = &self.misc(provided_span); - let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); + let trace = mk_trace(provided_span, formal_and_expected_inputs[*expected_idx], provided_ty); if !matches!(trace.cause.as_failure_code(*e), FailureCode::Error0308(_)) { self.err_ctxt().report_and_explain_type_error(trace, *e).emit(); return true; @@ -774,8 +783,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { { let (formal_ty, expected_ty) = formal_and_expected_inputs[*expected_idx]; let (provided_ty, provided_arg_span) = provided_arg_tys[*provided_idx]; - let cause = &self.misc(provided_arg_span); - let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); + let trace = mk_trace(provided_arg_span, (formal_ty, expected_ty), provided_ty); let mut err = self.err_ctxt().report_and_explain_type_error(trace, *err); self.emit_coerce_suggestions( &mut err, @@ -847,8 +855,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let (formal_ty, expected_ty) = formal_and_expected_inputs[expected_idx]; let (provided_ty, provided_span) = provided_arg_tys[provided_idx]; if let Compatibility::Incompatible(error) = compatibility { - let cause = &self.misc(provided_span); - let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); + let trace = mk_trace(provided_span, (formal_ty, expected_ty), provided_ty); if let Some(e) = error { self.err_ctxt().note_type_err( &mut err, diff --git a/src/test/ui/argument-suggestions/formal-and-expected-differ.rs b/src/test/ui/argument-suggestions/formal-and-expected-differ.rs new file mode 100644 index 00000000000..5e3b55ca525 --- /dev/null +++ b/src/test/ui/argument-suggestions/formal-and-expected-differ.rs @@ -0,0 +1,25 @@ +pub trait Foo { + type T; +} + +impl Foo for i32 { + type T = f32; +} + +pub struct U<T1, T2>(T1, S<T2>) +where + T1: Foo<T = T2>; + +pub struct S<T>(T); + +fn main() { + // The error message here isn't great -- it has to do with the fact that the + // `expected_inputs_for_expected_output` deduced inputs differs from the inputs + // that we infer from the constraints of the signature. + // + // I am not really sure what the best way of presenting this error message is, + // since right now it just suggests changing `3u32` <=> `3f32` back and forth. + let _: U<_, u32> = U(1, S(3u32)); + //~^ ERROR mismatched types + //~| ERROR mismatched types +} diff --git a/src/test/ui/argument-suggestions/formal-and-expected-differ.stderr b/src/test/ui/argument-suggestions/formal-and-expected-differ.stderr new file mode 100644 index 00000000000..905875b5277 --- /dev/null +++ b/src/test/ui/argument-suggestions/formal-and-expected-differ.stderr @@ -0,0 +1,30 @@ +error[E0308]: mismatched types + --> $DIR/formal-and-expected-differ.rs:22:29 + | +LL | let _: U<_, u32> = U(1, S(3u32)); + | - ^^^^^^^ expected `f32`, found `u32` + | | + | arguments to this struct are incorrect + | + = note: expected struct `S<f32>` + found struct `S<u32>` +note: tuple struct defined here + --> $DIR/formal-and-expected-differ.rs:9:12 + | +LL | pub struct U<T1, T2>(T1, S<T2>) + | ^ + +error[E0308]: mismatched types + --> $DIR/formal-and-expected-differ.rs:22:24 + | +LL | let _: U<_, u32> = U(1, S(3u32)); + | --------- ^^^^^^^^^^^^^ expected `u32`, found `f32` + | | + | expected due to this + | + = note: expected struct `U<_, u32>` + found struct `U<i32, f32>` + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0308`. |