Account for `Path`s on `is_suggestable_infer_ty`

Fix #68162.

3 files changed, 86 insertions, 45 deletions

diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index ad750d5ab83..dca3289747e 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -1806,6 +1806,16 @@ fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
     }
 }
 
+fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
+    generic_args
+        .iter()
+        .filter_map(|arg| match arg {
+            hir::GenericArg::Type(ty) => Some(ty),
+            _ => None,
+        })
+        .any(is_suggestable_infer_ty)
+}
+
 /// Whether `ty` is a type with `_` placeholders that can be infered. Used in diagnostics only to
 /// use inference to provide suggestions for the appropriate type if possible.
 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
@@ -1815,13 +1825,16 @@ fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
         Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
         Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
         Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
-        Def(_, generic_args) => generic_args
-            .iter()
-            .filter_map(|arg| match arg {
-                hir::GenericArg::Type(ty) => Some(ty),
-                _ => None,
-            })
-            .any(is_suggestable_infer_ty),
+        Def(_, generic_args) => are_suggestable_generic_args(generic_args),
+        Path(hir::QPath::TypeRelative(ty, segment)) => {
+            is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.generic_args().args)
+        }
+        Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
+            ty_opt.map_or(false, is_suggestable_infer_ty)
+                || segments
+                    .iter()
+                    .any(|segment| are_suggestable_generic_args(segment.generic_args().args))
+        }
         _ => false,
     }
 }
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.rs b/src/test/ui/typeck/typeck_type_placeholder_item.rs
index adecbd7e5b4..86c7c52b271 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.rs
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.rs
@@ -68,6 +68,13 @@ struct Test10 {
 }
 
 pub fn main() {
+    static A = 42;
+    //~^ ERROR missing type for `static` item
+    static B: _ = 42;
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    static C: Option<_> = Some(42);
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+
     fn fn_test() -> _ { 5 }
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
 
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
index 05326a3e07a..f740a9f7f34 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
@@ -1,35 +1,35 @@
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:146:18
+  --> $DIR/typeck_type_placeholder_item.rs:153:18
    |
 LL | struct BadStruct<_>(_);
    |                  ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:149:16
+  --> $DIR/typeck_type_placeholder_item.rs:156:16
    |
 LL | trait BadTrait<_> {}
    |                ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:159:19
+  --> $DIR/typeck_type_placeholder_item.rs:166:19
    |
 LL | struct BadStruct1<_, _>(_);
    |                   ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:159:22
+  --> $DIR/typeck_type_placeholder_item.rs:166:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                      ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:164:19
+  --> $DIR/typeck_type_placeholder_item.rs:171:19
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                   ^ expected identifier, found reserved identifier
 
 error[E0403]: the name `_` is already used for a generic parameter in this item's generic parameters
-  --> $DIR/typeck_type_placeholder_item.rs:159:22
+  --> $DIR/typeck_type_placeholder_item.rs:166:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                   -  ^ already used
@@ -177,8 +177,29 @@ LL |
 LL |     b: (T, T),
    |
 
+error: missing type for `static` item
+  --> $DIR/typeck_type_placeholder_item.rs:71:12
+   |
+LL |     static A = 42;
+   |            ^ help: provide a type for the item: `A: i32`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:73:15
+   |
+LL |     static B: _ = 42;
+   |               ^
+   |               |
+   |               not allowed in type signatures
+   |               help: replace `_` with the correct type: `i32`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:75:15
+   |
+LL |     static C: Option<_> = Some(42);
+   |               ^^^^^^^^^ not allowed in type signatures
+
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:71:21
+  --> $DIR/typeck_type_placeholder_item.rs:78:21
    |
 LL |     fn fn_test() -> _ { 5 }
    |                     ^
@@ -187,7 +208,7 @@ LL |     fn fn_test() -> _ { 5 }
    |                     help: replace with the correct return type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:74:23
+  --> $DIR/typeck_type_placeholder_item.rs:81:23
    |
 LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      -^--^-
@@ -197,7 +218,7 @@ LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      help: replace with the correct return type: `(i32, i32)`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:77:22
+  --> $DIR/typeck_type_placeholder_item.rs:84:22
    |
 LL |     static FN_TEST3: _ = "test";
    |                      ^
@@ -206,7 +227,7 @@ LL |     static FN_TEST3: _ = "test";
    |                      help: replace `_` with the correct type: `&'static str`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:80:22
+  --> $DIR/typeck_type_placeholder_item.rs:87:22
    |
 LL |     static FN_TEST4: _ = 145;
    |                      ^
@@ -215,13 +236,13 @@ LL |     static FN_TEST4: _ = 145;
    |                      help: replace `_` with the correct type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:83:22
+  --> $DIR/typeck_type_placeholder_item.rs:90:22
    |
 LL |     static FN_TEST5: (_, _) = (1, 2);
    |                      ^^^^^^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:86:20
+  --> $DIR/typeck_type_placeholder_item.rs:93:20
    |
 LL |     fn fn_test6(_: _) { }
    |                    ^ not allowed in type signatures
@@ -232,7 +253,7 @@ LL |     fn fn_test6<T>(_: T) { }
    |                ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:89:20
+  --> $DIR/typeck_type_placeholder_item.rs:96:20
    |
 LL |     fn fn_test7(x: _) { let _x: usize = x; }
    |                    ^ not allowed in type signatures
@@ -243,13 +264,13 @@ LL |     fn fn_test7<T>(x: T) { let _x: usize = x; }
    |                ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:92:29
+  --> $DIR/typeck_type_placeholder_item.rs:99:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:92:29
+  --> $DIR/typeck_type_placeholder_item.rs:99:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^ not allowed in type signatures
@@ -260,7 +281,7 @@ LL |     fn fn_test8<T>(_f: fn() -> T) { }
    |                ^^^             ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:115:12
+  --> $DIR/typeck_type_placeholder_item.rs:122:12
    |
 LL |         a: _,
    |            ^ not allowed in type signatures
@@ -279,13 +300,13 @@ LL |         b: (T, T),
    |
 
 error[E0282]: type annotations needed
-  --> $DIR/typeck_type_placeholder_item.rs:120:27
+  --> $DIR/typeck_type_placeholder_item.rs:127:27
    |
 LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                           ^^^^^^ cannot infer type
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:120:28
+  --> $DIR/typeck_type_placeholder_item.rs:127:28
    |
 LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                            ^  ^ not allowed in type signatures
@@ -293,7 +314,7 @@ LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                            not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:124:30
+  --> $DIR/typeck_type_placeholder_item.rs:131:30
    |
 LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             -^--^-
@@ -303,7 +324,7 @@ LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             help: replace with the correct return type: `(i32, i32)`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:127:33
+  --> $DIR/typeck_type_placeholder_item.rs:134:33
    |
 LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           ------^-
@@ -312,7 +333,7 @@ LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           help: replace with the correct return type: `(i32, i32)`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:146:21
+  --> $DIR/typeck_type_placeholder_item.rs:153:21
    |
 LL | struct BadStruct<_>(_);
    |                     ^ not allowed in type signatures
@@ -323,7 +344,7 @@ LL | struct BadStruct<T>(T);
    |                  ^  ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:151:15
+  --> $DIR/typeck_type_placeholder_item.rs:158:15
    |
 LL | impl BadTrait<_> for BadStruct<_> {}
    |               ^                ^ not allowed in type signatures
@@ -336,13 +357,13 @@ LL | impl<T> BadTrait<T> for BadStruct<T> {}
    |     ^^^          ^                ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:154:34
+  --> $DIR/typeck_type_placeholder_item.rs:161:34
    |
 LL | fn impl_trait() -> impl BadTrait<_> {
    |                                  ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:159:25
+  --> $DIR/typeck_type_placeholder_item.rs:166:25
    |
 LL | struct BadStruct1<_, _>(_);
    |                         ^ not allowed in type signatures
@@ -353,7 +374,7 @@ LL | struct BadStruct1<T, _>(T);
    |                   ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:164:25
+  --> $DIR/typeck_type_placeholder_item.rs:171:25
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                         ^ not allowed in type signatures
@@ -364,7 +385,7 @@ LL | struct BadStruct2<K, T>(K, T);
    |                   ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:168:14
+  --> $DIR/typeck_type_placeholder_item.rs:175:14
    |
 LL | type X = Box<_>;
    |              ^ not allowed in type signatures
@@ -381,7 +402,7 @@ LL |     fn test10<T>(&self, _x : T) { }
    |              ^^^             ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:132:31
+  --> $DIR/typeck_type_placeholder_item.rs:139:31
    |
 LL |     fn method_test1(&self, x: _);
    |                               ^ not allowed in type signatures
@@ -392,7 +413,7 @@ LL |     fn method_test1<T>(&self, x: T);
    |                    ^^^           ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:134:31
+  --> $DIR/typeck_type_placeholder_item.rs:141:31
    |
 LL |     fn method_test2(&self, x: _) -> _;
    |                               ^     ^ not allowed in type signatures
@@ -405,7 +426,7 @@ LL |     fn method_test2<T>(&self, x: T) -> T;
    |                    ^^^           ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:136:31
+  --> $DIR/typeck_type_placeholder_item.rs:143:31
    |
 LL |     fn method_test3(&self) -> _;
    |                               ^ not allowed in type signatures
@@ -416,7 +437,7 @@ LL |     fn method_test3<T>(&self) -> T;
    |                    ^^^           ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:138:26
+  --> $DIR/typeck_type_placeholder_item.rs:145:26
    |
 LL |     fn assoc_fn_test1(x: _);
    |                          ^ not allowed in type signatures
@@ -427,7 +448,7 @@ LL |     fn assoc_fn_test1<T>(x: T);
    |                      ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:140:26
+  --> $DIR/typeck_type_placeholder_item.rs:147:26
    |
 LL |     fn assoc_fn_test2(x: _) -> _;
    |                          ^     ^ not allowed in type signatures
@@ -440,7 +461,7 @@ LL |     fn assoc_fn_test2<T>(x: T) -> T;
    |                      ^^^    ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:142:28
+  --> $DIR/typeck_type_placeholder_item.rs:149:28
    |
 LL |     fn assoc_fn_test3() -> _;
    |                            ^ not allowed in type signatures
@@ -462,7 +483,7 @@ LL |     fn clone_from<T>(&mut self, other: T) { *self = Test9; }
    |                  ^^^                   ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:102:34
+  --> $DIR/typeck_type_placeholder_item.rs:109:34
    |
 LL |         fn fn_test10(&self, _x : _) { }
    |                                  ^ not allowed in type signatures
@@ -473,7 +494,7 @@ LL |         fn fn_test10<T>(&self, _x : T) { }
    |                     ^^^             ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:110:41
+  --> $DIR/typeck_type_placeholder_item.rs:117:41
    |
 LL |         fn clone_from(&mut self, other: _) { *self = FnTest9; }
    |                                         ^ not allowed in type signatures
@@ -484,7 +505,7 @@ LL |         fn clone_from<T>(&mut self, other: T) { *self = FnTest9; }
    |                      ^^^                   ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:174:21
+  --> $DIR/typeck_type_placeholder_item.rs:181:21
    |
 LL | type Y = impl Trait<_>;
    |                     ^ not allowed in type signatures
@@ -508,7 +529,7 @@ LL |     fn clone(&self) -> _ { Test9 }
    |                        help: replace with the correct return type: `Test9`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:99:31
+  --> $DIR/typeck_type_placeholder_item.rs:106:31
    |
 LL |         fn fn_test9(&self) -> _ { () }
    |                               ^
@@ -517,7 +538,7 @@ LL |         fn fn_test9(&self) -> _ { () }
    |                               help: replace with the correct return type: `()`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:107:28
+  --> $DIR/typeck_type_placeholder_item.rs:114:28
    |
 LL |         fn clone(&self) -> _ { FnTest9 }
    |                            ^
@@ -525,7 +546,7 @@ LL |         fn clone(&self) -> _ { FnTest9 }
    |                            not allowed in type signatures
    |                            help: replace with the correct return type: `main::FnTest9`
 
-error: aborting due to 55 previous errors
+error: aborting due to 58 previous errors
 
 Some errors have detailed explanations: E0121, E0282, E0403.
 For more information about an error, try `rustc --explain E0121`.