[clang] [clang][Sema] Add diagnostic note for reference of function-like macros requiring without parentheses (PR #123495)

[Shafik Yaghmour via cfe-commits]

================
@@ -180,3 +182,11 @@ void test2() {
   // expected-error at -3 {{use of undeclared identifier}}
   // expected-note at -4 {{cannot use initializer list at the beginning of a macro argument}}
 }
+
+#define LIM() 10 
+// expected-note at -1 {{'LIM' is defined here as a function-like macro; did you mean 'LIM(...)'}}
+
+void test3() {
+  int iter = LIM;
----------------
shafik wrote:

We should also cover other cases as well in the tests e.g.:

```cpp
#define F() 42
int x = F;

void g(int);

void f() {
    F + 1;
    g(F);
}
```

https://github.com/llvm/llvm-project/pull/123495