diff options
| -rw-r--r-- | compiler/rustc_typeck/src/collect/type_of.rs | 54 | ||||
| -rw-r--r-- | src/test/ui/suggestions/unnamable-types.rs | 33 | ||||
| -rw-r--r-- | src/test/ui/suggestions/unnamable-types.stderr | 66 |
3 files changed, 140 insertions, 13 deletions
diff --git a/compiler/rustc_typeck/src/collect/type_of.rs b/compiler/rustc_typeck/src/collect/type_of.rs index 29a87b18a9e..38678cc76e0 100644 --- a/compiler/rustc_typeck/src/collect/type_of.rs +++ b/compiler/rustc_typeck/src/collect/type_of.rs @@ -749,6 +749,17 @@ fn infer_placeholder_type( span: Span, item_ident: Ident, ) -> Ty<'_> { + fn contains_anonymous(ty: Ty<'_>) -> bool { + for gen_arg in ty.walk() { + if let ty::subst::GenericArgKind::Type(inner_ty) = gen_arg.unpack() { + if let ty::FnDef(..) | ty::Closure(..) | ty::Generator(..) = inner_ty.kind() { + return true; + } + } + } + false + } + let ty = tcx.diagnostic_only_typeck(def_id).node_type(body_id.hir_id); // If this came from a free `const` or `static mut?` item, @@ -760,24 +771,41 @@ fn infer_placeholder_type( // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type. // We are typeck and have the real type, so remove that and suggest the actual type. err.suggestions.clear(); - err.span_suggestion( - span, - "provide a type for the item", - format!("{}: {}", item_ident, ty), - Applicability::MachineApplicable, - ) - .emit_unless(ty.references_error()); + + // Suggesting unnameable types won't help. + if !contains_anonymous(ty) { + err.span_suggestion( + span, + "provide a type for the item", + format!("{}: {}", item_ident, ty), + Applicability::MachineApplicable, + ); + } else { + err.span_note( + tcx.hir().body(body_id).value.span, + &format!("however, the inferred type `{}` cannot be named", ty.to_string()), + ); + } + + err.emit_unless(ty.references_error()); } None => { let mut diag = bad_placeholder_type(tcx, vec![span]); if !ty.references_error() { - diag.span_suggestion( - span, - "replace with the correct type", - ty.to_string(), - Applicability::MaybeIncorrect, - ); + if !contains_anonymous(ty) { + diag.span_suggestion( + span, + "replace with the correct type", + ty.to_string(), + Applicability::MaybeIncorrect, + ); + } else { + diag.span_note( + tcx.hir().body(body_id).value.span, + &format!("however, the inferred type `{}` cannot be named", ty.to_string()), + ); + } } diag.emit(); diff --git a/src/test/ui/suggestions/unnamable-types.rs b/src/test/ui/suggestions/unnamable-types.rs new file mode 100644 index 00000000000..ed70bcf5484 --- /dev/null +++ b/src/test/ui/suggestions/unnamable-types.rs @@ -0,0 +1,33 @@ +// Test that we do not suggest to add type annotations for unnamable types. + +#![crate_type="lib"] +#![feature(generators)] + +const A = 5; +//~^ ERROR: missing type for `const` item +//~| HELP: provide a type for the item + +static B: _ = "abc"; +//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures +//~| NOTE: not allowed in type signatures +//~| HELP: replace with the correct type + + +const C: _ = || 42; +//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures +//~| NOTE: not allowed in type signatures +//~| NOTE: however, the inferred type + +struct S<T> { t: T } +const D = S { t: || -> i32 { 42 } }; +//~^ ERROR: missing type for `const` item +//~| NOTE: however, the inferred type + +fn foo() -> i32 { 42 } +const E = S { t: foo }; +//~^ ERROR: missing type for `const` item +//~| NOTE: however, the inferred type + +const F = || -> i32 { yield 0; return 1; }; +//~^ ERROR: missing type for `const` item +//~| NOTE: however, the inferred type diff --git a/src/test/ui/suggestions/unnamable-types.stderr b/src/test/ui/suggestions/unnamable-types.stderr new file mode 100644 index 00000000000..8082707fd3c --- /dev/null +++ b/src/test/ui/suggestions/unnamable-types.stderr @@ -0,0 +1,66 @@ +error: missing type for `const` item + --> $DIR/unnamable-types.rs:6:7 + | +LL | const A = 5; + | ^ help: provide a type for the item: `A: i32` + +error[E0121]: the type placeholder `_` is not allowed within types on item signatures + --> $DIR/unnamable-types.rs:10:11 + | +LL | static B: _ = "abc"; + | ^ + | | + | not allowed in type signatures + | help: replace with the correct type: `&str` + +error[E0121]: the type placeholder `_` is not allowed within types on item signatures + --> $DIR/unnamable-types.rs:16:10 + | +LL | const C: _ = || 42; + | ^ not allowed in type signatures + | +note: however, the inferred type `[closure@$DIR/unnamable-types.rs:16:14: 16:19]` cannot be named + --> $DIR/unnamable-types.rs:16:14 + | +LL | const C: _ = || 42; + | ^^^^^ + +error: missing type for `const` item + --> $DIR/unnamable-types.rs:22:7 + | +LL | const D = S { t: || -> i32 { 42 } }; + | ^ + | +note: however, the inferred type `S<[closure@$DIR/unnamable-types.rs:22:18: 22:34]>` cannot be named + --> $DIR/unnamable-types.rs:22:11 + | +LL | const D = S { t: || -> i32 { 42 } }; + | ^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: missing type for `const` item + --> $DIR/unnamable-types.rs:27:7 + | +LL | const E = S { t: foo }; + | ^ + | +note: however, the inferred type `S<fn() -> i32 {foo}>` cannot be named + --> $DIR/unnamable-types.rs:27:11 + | +LL | const E = S { t: foo }; + | ^^^^^^^^^^^^ + +error: missing type for `const` item + --> $DIR/unnamable-types.rs:31:7 + | +LL | const F = || -> i32 { yield 0; return 1; }; + | ^ + | +note: however, the inferred type `[generator@$DIR/unnamable-types.rs:31:11: 31:43 {i32, ()}]` cannot be named + --> $DIR/unnamable-types.rs:31:11 + | +LL | const F = || -> i32 { yield 0; return 1; }; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: aborting due to 6 previous errors + +For more information about this error, try `rustc --explain E0121`. |