[clang] [Clang] Remove explicit object from non member function. (PR #148807)

[Corentin Jabot via cfe-commits]

https://github.com/cor3ntin created https://github.com/llvm/llvm-project/pull/148807

To avoid crashing later (as we assume only member functions can have explicit parameters)

Fixes #113185

>From bf204f023a4f84732c5876ff86e7de603fd95aac Mon Sep 17 00:00:00 2001
From: Corentin Jabot <corentinjabot at gmail.com>
Date: Tue, 15 Jul 2025 11:06:03 +0200
Subject: [PATCH] [Clang] Remove explicit object from non member function.

To avoid crashing later (as we assume only member functions
can have explicit parameters)

Fixes #113185
---
 clang/lib/Sema/SemaType.cpp                |  4 +++-
 clang/test/SemaCXX/cxx2b-deducing-this.cpp | 10 ++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 661746731fdcc..bb114aff2366b 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -4860,7 +4860,9 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
             S.Diag(First->getBeginLoc(),
                    diag::err_explicit_object_parameter_invalid)
                 << First->getSourceRange();
-
+          // Do let non-member function have explicit parameters
+          // to not break assumptions elsewhere in the code.
+          First->setExplicitObjectParameterLoc(SourceLocation());
           D.setInvalidType();
           AreDeclaratorChunksValid = false;
         }
diff --git a/clang/test/SemaCXX/cxx2b-deducing-this.cpp b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
index 6987d0c020457..2253cbb26285e 100644
--- a/clang/test/SemaCXX/cxx2b-deducing-this.cpp
+++ b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
@@ -1347,3 +1347,13 @@ int main() {
     // expected-note@#S3-f-cand2 {{candidate function not viable: no known conversion from 'S3' to 'int' for object argument}}
 }
 }
+
+namespace GH113185 {
+
+void Bar(this int) { // expected-note {{candidate function}}
+    // expected-error at -1 {{an explicit object parameter cannot appear in a non-member function}}
+    Bar(0);
+    Bar(); // expected-error {{no matching function for call to 'Bar'}}
+}
+
+}