Fix ICE with struct ctors and const generics.

This commit fixes a ICE where struct constructors were resulting in an
ICE with const generics. Previously, a `match` in `type_of` did not have
an arm for the `DefKind::Ctor` resolutions and therefore would assume
that the type did not have generics.

src/test/ui/const-generics/cannot-infer-type-for-const-param.rs

@@ -1,8 +1,9 @@
+// compile-pass
 #![feature(const_generics)]
 //~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
 
-// We should probably be able to infer the types here. However, this test is checking that we don't
-// get an ICE in this case. It may be modified later to not be an error.
+// This test confirms that the types can be inferred correctly for this example with const
+// generics. Previously this would ICE, and more recently error.
 
 struct Foo<const NUM_BYTES: usize>(pub [u8; NUM_BYTES]);
 

src/test/ui/const-generics/cannot-infer-type-for-const-param.stderr

@@ -1,25 +1,6 @@
 warning: the feature `const_generics` is incomplete and may cause the compiler to crash
-  --> $DIR/cannot-infer-type-for-const-param.rs:1:12
+  --> $DIR/cannot-infer-type-for-const-param.rs:2:12
    |
 LL | #![feature(const_generics)]
    |            ^^^^^^^^^^^^^^
 
-error[E0282]: type annotations needed
-  --> $DIR/cannot-infer-type-for-const-param.rs:10:19
-   |
-LL |     let _ = Foo::<3>([1, 2, 3]);
-   |                   ^ cannot infer type for `{integer}`
-
-error[E0308]: mismatched types
-  --> $DIR/cannot-infer-type-for-const-param.rs:10:22
-   |
-LL |     let _ = Foo::<3>([1, 2, 3]);
-   |                      ^^^^^^^^^ expected `3`, found `3usize`
-   |
-   = note: expected type `[u8; _]`
-              found type `[u8; 3]`
-
-error: aborting due to 2 previous errors
-
-Some errors have detailed explanations: E0282, E0308.
-For more information about an error, try `rustc --explain E0282`.

src/test/ui/const-generics/issue-60818-struct-constructors.rs

@@ -0,0 +1,10 @@
+// compile-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+struct Generic<const V: usize>;
+
+fn main() {
+    let _ = Generic::<0>;
+}

src/test/ui/const-generics/issue-60818-struct-constructors.stderr

@@ -0,0 +1,6 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/issue-60818-struct-constructors.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+