Fix calling function pointer const parameters. Also fixes inference of

function pointer const parameters.

src/test/ui/const-generics/fn-const-param-call.rs

@@ -0,0 +1,20 @@
+// run-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+fn function() -> u32 {
+    17
+}
+
+struct Wrapper<const F: fn() -> u32>;
+
+impl<const F: fn() -> u32> Wrapper<{F}> {
+    fn call() -> u32 {
+        F()
+    }
+}
+
+fn main() {
+    assert_eq!(Wrapper::<{function}>::call(), 17);
+}

src/test/ui/const-generics/fn-const-param-call.stderr

@@ -0,0 +1,8 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/fn-const-param-call.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+

src/test/ui/const-generics/fn-const-param-infer.rs

@@ -0,0 +1,26 @@
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+struct Checked<const F: fn(usize) -> bool>;
+
+fn not_one(val: usize) -> bool { val != 1 }
+fn not_two(val: usize) -> bool { val != 2 }
+
+fn generic_arg<T>(val: T) -> bool { true }
+
+fn generic<T>(val: usize) -> bool { val != 1 }
+
+fn main() {
+    let _: Option<Checked<{not_one}>> = None;
+    let _: Checked<{not_one}> = Checked::<{not_one}>;
+    let _: Checked<{not_one}> = Checked::<{not_two}>; //~ mismatched types
+
+    let _ = Checked::<{generic_arg}>;
+    let _ = Checked::<{generic_arg::<usize>}>;
+    let _ = Checked::<{generic_arg::<u32>}>;  //~ mismatched types
+
+    let _ = Checked::<{generic}>; //~ type annotations needed
+    let _ = Checked::<{generic::<u16>}>;
+    let _: Checked<{generic::<u16>}> = Checked::<{generic::<u16>}>;
+    let _: Checked<{generic::<u32>}> = Checked::<{generic::<u16>}>; //~ mismatched types
+}

src/test/ui/const-generics/fn-const-param-infer.stderr

@@ -0,0 +1,45 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/fn-const-param-infer.rs:1:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0308]: mismatched types
+  --> $DIR/fn-const-param-infer.rs:16:33
+   |
+LL |     let _: Checked<{not_one}> = Checked::<{not_two}>;
+   |                                 ^^^^^^^^^^^^^^^^^^^^ expected `Scalar(AllocId(1).0x0) : fn(usize) -> bool`, found `Scalar(AllocId(10).0x0) : fn(usize) -> bool`
+   |
+   = note: expected type `Checked<>`
+              found type `Checked<>`
+
+error[E0308]: mismatched types
+  --> $DIR/fn-const-param-infer.rs:20:24
+   |
+LL |     let _ = Checked::<{generic_arg::<u32>}>;
+   |                        ^^^^^^^^^^^^^^^^^^ expected usize, found u32
+   |
+   = note: expected type `fn(usize) -> bool`
+              found type `fn(u32) -> bool {generic_arg::<u32>}`
+
+error[E0282]: type annotations needed
+  --> $DIR/fn-const-param-infer.rs:22:24
+   |
+LL |     let _ = Checked::<{generic}>;
+   |                        ^^^^^^^ cannot infer type for `T`
+
+error[E0308]: mismatched types
+  --> $DIR/fn-const-param-infer.rs:25:40
+   |
+LL |     let _: Checked<{generic::<u32>}> = Checked::<{generic::<u16>}>;
+   |                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Scalar(AllocId(7).0x0) : fn(usize) -> bool`, found `Scalar(AllocId(20).0x0) : fn(usize) -> bool`
+   |
+   = note: expected type `Checked<>`
+              found type `Checked<>`
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0282, E0308.
+For more information about an error, try `rustc --explain E0282`.