[clang][Sema] Fix caret position to be on the non null parameter

[Grillo]

Summary

When checking for non null arguments the wrong SourceLocation was given,
this fix to pass the proper argument's location.

Reported in PR58273.

[aaron.ballman]

Thank you for the fix!

Can you add test coverage to show the behavioral change? You can either position the problematic null argument on its own line (so you can validate the correct position) or use -fdiagnostics-print-source-range-info to check a specific range. Also, can you add a release note about the fix to clang/docs/ReleaseNotes.rst?

[Grillo]

Add test coverage and release note about the fix to clang/docs/ReleaseNotes.rst

[aaron.ballman]

LGTM aside from a tiny grammar nit. Thank you for the fix! If you'd like me to commit this on your behalf, I can fix up the release note myself when landing, but please let me know what name and email address you'd like me to use for patch attribution.

clang/docs/ReleaseNotes.rst

328

[Grillo]

In D136355#3875265, @aaron.ballman wrote:

LGTM aside from a tiny grammar nit. Thank you for the fix! If you'd like me to commit this on your behalf, I can fix up the release note myself when landing, but please let me know what name and email address you'd like me to use for patch attribution.

If you could that would be great! My name and email is Arthur Grillo <[e-mail]>.

Best Regards,
Arthur Grillo

clang/docs/ReleaseNotes.rst

- Copy-elided initialization of lock scopes is now handled differently in
   the lock scope by value. This could result in new warnings if code depended
   on the previous undocumented behavior. As a side effect of this change,
   constructor calls outside of initializer expressions are no longer ignored,
   which can result in new warnings (or make existing warnings disappear).
 - The wording of diagnostics regarding arithmetic on fixed-sized arrays and
   pointers is improved to include the type of the array and whether it's cast
   to another type. This should improve comprehension for why an index is
   out-of-bounds.
+- Clang now correctly point to the problematic parameter for the ``-Wnonnull``
+  warning.
+  This fixes `Issue 58273 <https://github.com/llvm/llvm-project/issues/58273>`_.
 
 Non-comprehensive list of changes in this release
 -------------------------------------------------
 - It's now possible to set the crash diagnostics directory through
   the environment variable ``CLANG_CRASH_DIAGNOSTICS_DIR``.
   The ``-fcrash-diagnostics-dir`` flag takes precedence.
 - When using header modules, inclusion of a private header and violations of
   the `use-declaration rules

clang/lib/Sema/SemaChecking.cpp

if (Proto) {
       }
     }
   }
 
   // Check for non-null arguments.
   for (unsigned ArgIndex = 0, ArgIndexEnd = NonNullArgs.size();
        ArgIndex != ArgIndexEnd; ++ArgIndex) {
     if (NonNullArgs[ArgIndex])
-      CheckNonNullArgument(S, Args[ArgIndex], CallSiteLoc);
+      CheckNonNullArgument(S, Args[ArgIndex], Args[ArgIndex]->getExprLoc());
   }
 }
 
 // 16 byte ByVal alignment not due to a vector member is not honoured by XL
 // on AIX. Emit a warning here that users are generating binary incompatible
 // code to be safe.
 // Here we try to get information about the alignment of the struct member
 // from the struct passed to the caller function. We only warn when the struct

clang/test/Sema/non-null-warning.c

 int *foo3(int * _Nonnull x) { // expected-warning {{nullability specifier '_Nonnull' conflicts with existing specifier '_Nullable'}}
   return 0;
 }
 
 int * ret_nonnull(void) {
   return 0; // expected-warning {{null returned from function that requires a non-null return value}}
 }
 
+int foo4(int * _Nonnull x, int * y) {
+  return 0;
+}
+
 #define SAFE_CALL(X) if (X) foo(X)
 int main (void) {
   foo(0); // expected-warning {{null passed to a callee that requires a non-null argument}}
   (void)sizeof(foo(0)); // expect no diagnostic in unevaluated context.
   SAFE_CALL(0); // expect no diagnostic for unreachable code.
+  foo4(
+       0, // expected-warning {{null passed to a callee that requires a non-null argument}}
+       0);
 }