Fix negative integer literal test

Co-Authored-By: Gabriel Smith <yodaldevoid@users.noreply.github.com>

Author: varkor

src/test/ui/const-generics/const-expression-parameter.rs

@@ -1,24 +1,22 @@
 #![feature(const_generics)]
 //~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
 
-fn u32_identity<const X: u32>() -> u32 {
+fn i32_identity<const X: i32>() -> i32 {
     5
 }
 
 fn foo_a() {
-    u32_identity::<-1>(); //~ ERROR expected identifier, found `<-`
+    i32_identity::<-1>(); //~ ERROR expected identifier, found `<-`
 }
 
 fn foo_b() {
-    u32_identity::<1 + 2>(); //~ ERROR expected one of `,` or `>`, found `+`
+    i32_identity::<1 + 2>(); //~ ERROR expected one of `,` or `>`, found `+`
 }
 
 fn foo_c() {
-    u32_identity::< -1 >(); // ok
-    // FIXME(const_generics)
-    //~^^ ERROR cannot apply unary operator `-` to type `u32` [E0600]
+    i32_identity::< -1 >(); // ok
 }
 
 fn main() {
-    u32_identity::<5>(); // ok
+    i32_identity::<5>(); // ok
 }

src/test/ui/const-generics/const-expression-parameter.stderr

@@ -1,13 +1,13 @@
 error: expected identifier, found `<-`
   --> $DIR/const-expression-parameter.rs:9:19
    |
-LL |     u32_identity::<-1>(); //~ ERROR expected identifier, found `<-`
+LL |     i32_identity::<-1>(); //~ ERROR expected identifier, found `<-`
    |                   ^^ expected identifier
 
 error: expected one of `,` or `>`, found `+`
   --> $DIR/const-expression-parameter.rs:13:22
    |
-LL |     u32_identity::<1 + 2>(); //~ ERROR expected one of `,` or `>`, found `+`
+LL |     i32_identity::<1 + 2>(); //~ ERROR expected one of `,` or `>`, found `+`
    |                      ^ expected one of `,` or `>` here
 
 warning: the feature `const_generics` is incomplete and may cause the compiler to crash
@@ -16,14 +16,5 @@ warning: the feature `const_generics` is incomplete and may cause the compiler t
 LL | #![feature(const_generics)]
    |            ^^^^^^^^^^^^^^
 
-error[E0600]: cannot apply unary operator `-` to type `u32`
-  --> $DIR/const-expression-parameter.rs:17:21
-   |
-LL |     u32_identity::< -1 >(); // ok
-   |                     ^^ cannot apply unary operator `-`
-   |
-   = note: unsigned values cannot be negated
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0600`.