[clang] 5f20f9a - [clang][AST] Remove HasFirstArg assertion in CallExpr::getBeginLoc() (#130725)

[via cfe-commits]

Author: Nathan Ridge
Date: 2025-03-12T01:01:52-04:00
New Revision: 5f20f9a0126165ed64c39b9a23559136691d9f97

URL: https://github.com/llvm/llvm-project/commit/5f20f9a0126165ed64c39b9a23559136691d9f97
DIFF: https://github.com/llvm/llvm-project/commit/5f20f9a0126165ed64c39b9a23559136691d9f97.diff

LOG: [clang][AST] Remove HasFirstArg assertion in CallExpr::getBeginLoc() (#130725)

There are cases where the assertion legitimately does not hold (e.g.
CallExpr::CreateTemporary()), and there's no readily available way to
tell such cases apart.

Fixes https://github.com/llvm/llvm-project/issues/130272

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/AST/Expr.cpp
    clang/test/AST/ast-dump-cxx2b-deducing-this.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cfbeb2f429dc5..48da5558b3f38 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -308,6 +308,7 @@ Bug Fixes to C++ Support
 - Correctly diagnoses template template paramters which have a pack parameter
   not in the last position.
 - Clang now correctly parses ``if constexpr`` expressions in immediate function context. (#GH123524)
+- Fixed an assertion failure affecting code that uses C++23 "deducing this". (#GH130272)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

diff  --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index ccfec7fda0cbc..1dde64f193dbd 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1656,9 +1656,11 @@ SourceLocation CallExpr::getBeginLoc() const {
     if (const auto *Method =
             dyn_cast_if_present<const CXXMethodDecl>(getCalleeDecl());
         Method && Method->isExplicitObjectMemberFunction()) {
-      bool HasFirstArg = getNumArgs() > 0 && getArg(0);
-      assert(HasFirstArg);
-      if (HasFirstArg)
+      // Note: while we typically expect the call to have a first argument
+      // here, we can't assert it because in some cases it does not, e.g.
+      // calls created with CallExpr::CreateTemporary() during overload
+      // resolution.
+      if (getNumArgs() > 0 && getArg(0))
         return getArg(0)->getBeginLoc();
     }
   }

diff  --git a/clang/test/AST/ast-dump-cxx2b-deducing-this.cpp b/clang/test/AST/ast-dump-cxx2b-deducing-this.cpp
index abe9d6a5b5bc6..fc86aeb3e5ec3 100644
--- a/clang/test/AST/ast-dump-cxx2b-deducing-this.cpp
+++ b/clang/test/AST/ast-dump-cxx2b-deducing-this.cpp
@@ -26,3 +26,12 @@ struct S {
   // CHECK-NEXT:   `-DeclRefExpr 0x{{[^ ]*}} <col:5> 'S<T>' lvalue ParmVar 0x{{[^ ]*}} 's' 'S<T>'
 };
 }
+
+namespace GH130272 {
+struct A {};
+struct B {
+  operator A(this B);
+};
+A a = A(B{});
+// CHECK: CallExpr 0x{{[^ ]*}} <col:9, col:11> 'A':'GH130272::A'
+}