[clang] [SemaCXX] Disallow deducing "this" on operator new and delete

[Rajveer100]

Resolves Issue #82249

As described in the issue, any deallocation function for a class X is a static member (even if not explicitly declared static).

[llvmbot]

@llvm/pr-subscribers-clang

Author: Rajveer Singh Bharadwaj (Rajveer100)

Changes

Resolves Issue #82249

As described in the issue, any deallocation function for a class X is a static member (even if not explicitly declared static).

---

Full diff: https://github.com/llvm/llvm-project/pull/82251.diff

2 Files Affected:

• (modified) clang/lib/Sema/SemaDeclCXX.cpp (+3-1)
• (modified) clang/test/SemaCXX/cxx2b-deducing-this.cpp (+4)

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index ab8a967b06a456..7a7b544d82b640 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -11391,7 +11391,9 @@ void Sema::CheckExplicitObjectMemberFunction(Declarator &D,
         << ExplicitObjectParam->getSourceRange();
   }
 
-  if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static) {
+  if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static ||
+      (D.getContext() == clang::DeclaratorContext::Member &&
+       D.isStaticMember())) {
     Diag(ExplicitObjectParam->getBeginLoc(),
          diag::err_explicit_object_parameter_nonmember)
         << D.getSourceRange() << /*static=*/0 << IsLambda;
diff --git a/clang/test/SemaCXX/cxx2b-deducing-this.cpp b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
index aab35828096a8e..530f8bf6af1b6b 100644
--- a/clang/test/SemaCXX/cxx2b-deducing-this.cpp
+++ b/clang/test/SemaCXX/cxx2b-deducing-this.cpp
@@ -16,6 +16,10 @@ struct S {
     static void f(this auto); // expected-error{{an explicit object parameter cannot appear in a static function}}
     virtual void f(this S); // expected-error{{an explicit object parameter cannot appear in a virtual function}}
 
+    // new and delete are implicitly static
+    void *operator new(this unsigned long); // expected-error{{an explicit object parameter cannot appear in a static function}}
+    void operator delete(this void*); // expected-error{{an explicit object parameter cannot appear in a static function}}
+    
     void g(this auto) const; // expected-error{{explicit object member function cannot have 'const' qualifier}}
     void h(this auto) &; // expected-error{{explicit object member function cannot have '&' qualifier}}
     void i(this auto) &&; // expected-error{{explicit object member function cannot have '&&' qualifier}}

[cor3ntin]

This change needs a release note.
Please add an entry to clang/docs/ReleaseNotes.rst in the section the most adapted to the change, and referencing any Github issue this change fixes. Thanks!

Besides that, I think the change makes sense, thanks!

[cor3ntin]

LGTM modulo nit

[shafik]

LGTM, thanks for submitting a fix.

[cor3ntin]

@Rajveer100 you need us to merge that for you?

[Rajveer100]

Considering the PR sounds good to the reviewers, yes it would be great to have it merged.

[cor3ntin]

Thanks for working on this!