Add regression test for naked functions with invalid asm syntax

Author: jam1garner

src/test/ui/asm/naked-functions.rs

@@ -209,3 +209,9 @@ pub unsafe extern "C" fn allow_compile_error_and_asm(a: u32) -> u32 {
     //~^ ERROR this is a user specified error
     asm!("", options(noreturn))
 }
+
+#[naked]
+pub unsafe extern "C" fn invalid_asm_syntax(a: u32) -> u32 {
+    asm!(invalid_syntax)
+    //~^ ERROR asm template must be a string literal
+}

src/test/ui/asm/naked-functions.stderr

@@ -16,6 +16,12 @@ error: this is a user specified error
 LL |     compile_error!("this is a user specified error");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error: asm template must be a string literal
+  --> $DIR/naked-functions.rs:215:10
+   |
+LL |     asm!(invalid_syntax)
+   |          ^^^^^^^^^^^^^^
+
 error: patterns not allowed in naked function parameters
   --> $DIR/naked-functions.rs:20:5
    |
@@ -267,6 +273,6 @@ error: naked functions cannot be inlined
 LL | #[inline(never)]
    | ^^^^^^^^^^^^^^^^
 
-error: aborting due to 32 previous errors; 2 warnings emitted
+error: aborting due to 33 previous errors; 2 warnings emitted
 
 For more information about this error, try `rustc --explain E0787`.