Add test with multiple type params failing inference

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -939,9 +939,7 @@ impl<'tcx> ResolvedTypeParamEraser<'tcx> {
     /// Replace not yet inferred const params with their def name.
     fn replace_infers(&self, c: &'tcx Const<'tcx>, index: u32, name: Symbol) -> &'tcx Const<'tcx> {
         match c.val {
-            ty::ConstKind::Infer(..) => {
+            ty::ConstKind::Infer(..) => self.tcx().mk_const_param(index, name, c.ty),
-                self.tcx().mk_const_param(index, name, c.ty)
-            }
             _ => c,
         }
     }

src/test/ui/inference/erase-type-params-in-label.rs

@@ -1,5 +1,8 @@
 fn main() {
-    let foo = new(1, ""); //~ ERROR E0283
+    let foo = foo(1, ""); //~ ERROR E0283
+}
+fn baz() {
+    let bar = bar(1, ""); //~ ERROR E0283
 }
 
 struct Bar<T, K, N: Default> {
@@ -8,6 +11,17 @@ struct Bar<T, K, N: Default> {
     n: N,
 }
 
-fn new<T, K, Z: Default>(t: T, k: K) -> Bar<T, K, Z> {
+fn bar<T, K, Z: Default>(t: T, k: K) -> Bar<T, K, Z> {
     Bar { t, k, n: Default::default() }
 }
+
+struct Foo<T, K, N: Default, M: Default> {
+    t: T,
+    k: K,
+    n: N,
+    m: M,
+}
+
+fn foo<T, K, W: Default, Z: Default>(t: T, k: K) -> Foo<T, K, W, Z> {
+    Foo { t, k, n: Default::default(), m: Default::default() }
+}

src/test/ui/inference/erase-type-params-in-label.stderr

@@ -1,22 +1,41 @@
-error[E0283]: type annotations needed for `Bar<i32, &str, Z>`
+error[E0283]: type annotations needed for `Foo<i32, &str, W, Z>`
   --> $DIR/erase-type-params-in-label.rs:2:15
    |
-LL |     let foo = new(1, "");
+LL |     let foo = foo(1, "");
-   |         ---   ^^^ cannot infer type for type parameter `Z` declared on the function `new`
+   |         ---   ^^^ cannot infer type for type parameter `W` declared on the function `foo`
    |         |
-   |         consider giving `foo` the explicit type `Bar<_, _, Z>`, where the type parameter `Z` is specified
+   |         consider giving `foo` the explicit type `Foo<_, _, W, Z>`, where the type parameter `W` is specified
    |
    = note: cannot satisfy `_: Default`
-note: required by a bound in `new`
+note: required by a bound in `foo`
-  --> $DIR/erase-type-params-in-label.rs:11:17
+  --> $DIR/erase-type-params-in-label.rs:25:17
    |
-LL | fn new<T, K, Z: Default>(t: T, k: K) -> Bar<T, K, Z> {
+LL | fn foo<T, K, W: Default, Z: Default>(t: T, k: K) -> Foo<T, K, W, Z> {
-   |                 ^^^^^^^ required by this bound in `new`
+   |                 ^^^^^^^ required by this bound in `foo`
 help: consider specifying the type arguments in the function call
    |
-LL |     let foo = new::<T, K, Z>(1, "");
+LL |     let foo = foo::<T, K, W, Z>(1, "");
+   |                  ++++++++++++++
+
+error[E0283]: type annotations needed for `Bar<i32, &str, Z>`
+  --> $DIR/erase-type-params-in-label.rs:5:15
+   |
+LL |     let bar = bar(1, "");
+   |         ---   ^^^ cannot infer type for type parameter `Z` declared on the function `bar`
+   |         |
+   |         consider giving `bar` the explicit type `Bar<_, _, Z>`, where the type parameter `Z` is specified
+   |
+   = note: cannot satisfy `_: Default`
+note: required by a bound in `bar`
+  --> $DIR/erase-type-params-in-label.rs:14:17
+   |
+LL | fn bar<T, K, Z: Default>(t: T, k: K) -> Bar<T, K, Z> {
+   |                 ^^^^^^^ required by this bound in `bar`
+help: consider specifying the type arguments in the function call
+   |
+LL |     let bar = bar::<T, K, Z>(1, "");
    |                  +++++++++++
 
-error: aborting due to previous error
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0283`.