[clang] [clang] Fix a crash when default argument is passed to an explicit object parameter (PR #177534)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Kartik (hax0kartik)

<details>
<summary>Changes</summary>

This is an invalid usecase and we should mark it as such after outputting a Diagnostic. Fixes #<!-- -->176639.

---
Full diff: https://github.com/llvm/llvm-project/pull/177534.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+1) 
- (modified) clang/lib/Sema/SemaDeclCXX.cpp (+1) 
- (modified) clang/test/SemaCXX/cxx2b-deducing-this.cpp (+15) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 791212dafd342..4cd25b767320a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -173,6 +173,7 @@ Bug Fixes to Attribute Support
 Bug Fixes to C++ Support
 ^^^^^^^^^^^^^^^^^^^^^^^^
 - Fixed a crash when instantiating ``requires`` expressions involving substitution failures in C++ concepts. (#GH176402)
+- Fixed a crash when a default argument is passed to an explicit object parameter. (#GH176639)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index c96189172a010..5837ecd6b9163 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -11600,6 +11600,7 @@ void Sema::CheckExplicitObjectMemberFunction(Declarator &D,
     Diag(ExplicitObjectParam->getLocation(),
          diag::err_explicit_object_default_arg)
         << ExplicitObjectParam->getSourceRange();
+    D.setInvalidType();
   }
 
   if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static ||
diff --git a/clang/test/SemaCXX/cxx2b-deducing-this.cpp b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
index a9e31c3d06676..99f41bbc99020 100644
--- a/clang/test/SemaCXX/cxx2b-deducing-this.cpp
+++ b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
@@ -1400,3 +1400,18 @@ a void Bar(this int) { // expected-note {{candidate function}}
 }
 
 }
+
+namespace GH176639 {
+
+struct S {
+  void operator()(this S =) // expected-error {{the explicit object parameter cannot have a default argument}}
+          // expected-error at -1 {{expected ';' at end of declaration list}}
+          // expected-error at -2 {{expected expression}}
+};
+
+void foo() {
+  S s{};
+  s(0); // expected-error {{no matching function for call to object of type 'S'}}
+}
+
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/177534