[clang] [clang] Implement P3144R2 "Deleting a Pointer to an Incomplete Type..." (PR #97733)
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Thu Jul 4 07:19:48 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Vlad Serebrennikov (Endilll)
<details>
<summary>Changes</summary>
This patch implements (not yet published) [P3144R2](https://wiki.edg.com/pub/Wg21stlouis2024/StrawPolls/p3144r2.pdf) "Deleting a Pointer to an Incomplete Type Should be Ill-formed". Wording changes (not yet merged into the working draft) read:
> 7.6.2.9 [expr.delete] Delete
> If the object being deleted has incomplete class type at the point of deletion <del>and the complete class has a
non-trivial destructor or a deallocation function, the behavior is undefined</del>, <ins>the program is ill-formed</ins>.
We preserve status quo of emitting a warning when deleting a pointer to incomplete type up to, and including, C++23, but make it ill-formed since C++26. Same goes for deleting pointers to `void`, which has been allowed as an extension.
---
Full diff: https://github.com/llvm/llvm-project/pull/97733.diff
4 Files Affected:
- (modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+2)
- (modified) clang/lib/Sema/SemaExprCXX.cpp (+9-3)
- (modified) clang/test/CXX/drs/cwg5xx.cpp (+13-9)
- (modified) clang/test/SemaCXX/new-delete.cpp (+17-9)
``````````diff
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 3df64b2ecef1b..5c3e311ac6382 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -7991,6 +7991,8 @@ def err_ambiguous_delete_operand : Error<
def warn_delete_incomplete : Warning<
"deleting pointer to incomplete type %0 may cause undefined behavior">,
InGroup<DeleteIncomplete>;
+def err_delete_incomplete : Error<
+ "cannot delete pointer to incomplete type %0">;
def err_delete_incomplete_class_type : Error<
"deleting incomplete class type %0; no conversions to pointer type">;
def err_delete_explicit_conversion : Error<
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 69074f92a0286..fcf2189a308a8 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -3719,8 +3719,11 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
// The C++ standard bans deleting a pointer to a non-object type, which
// effectively bans deletion of "void*". However, most compilers support
// this, so we treat it as a warning unless we're in a SFINAE context.
- Diag(StartLoc, diag::ext_delete_void_ptr_operand)
- << Type << Ex.get()->getSourceRange();
+ // But we still prohibit this since C++26.
+ Diag(StartLoc, LangOpts.CPlusPlus26 ? diag::err_delete_incomplete
+ : diag::ext_delete_void_ptr_operand)
+ << (LangOpts.CPlusPlus26 ? Pointee : Type)
+ << Ex.get()->getSourceRange();
} else if (Pointee->isFunctionType() || Pointee->isVoidType() ||
Pointee->isSizelessType()) {
return ExprError(Diag(StartLoc, diag::err_delete_operand)
@@ -3729,7 +3732,10 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
// FIXME: This can result in errors if the definition was imported from a
// module but is hidden.
if (!RequireCompleteType(StartLoc, Pointee,
- diag::warn_delete_incomplete, Ex.get())) {
+ LangOpts.CPlusPlus26
+ ? diag::err_delete_incomplete
+ : diag::warn_delete_incomplete,
+ Ex.get())) {
if (const RecordType *RT = PointeeElem->getAs<RecordType>())
PointeeRD = cast<CXXRecordDecl>(RT->getDecl());
}
diff --git a/clang/test/CXX/drs/cwg5xx.cpp b/clang/test/CXX/drs/cwg5xx.cpp
index 9d890f981348a..6a0bb7a196669 100644
--- a/clang/test/CXX/drs/cwg5xx.cpp
+++ b/clang/test/CXX/drs/cwg5xx.cpp
@@ -1,9 +1,10 @@
-// RUN: %clang_cc1 -std=c++98 %s -verify=expected,cxx98-11,cxx98-14,cxx98-17,cxx98 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++11 %s -verify=expected,cxx98-11,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++14 %s -verify=expected,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++17 %s -verify=expected,since-cxx17,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++20 %s -verify=expected,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++23 %s -verify=expected,since-cxx23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++98 %s -verify=expected,cxx98-23,cxx98-11,cxx98-14,cxx98-17,cxx98 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 %s -verify=expected,cxx98-23,cxx98-11,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 %s -verify=expected,cxx98-23,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 %s -verify=expected,cxx98-23,since-cxx17,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++20 %s -verify=expected,cxx98-23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++23 %s -verify=expected,cxx98-23,since-cxx23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2c %s -verify=expected,since-cxx26,since-cxx23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
#if __cplusplus == 199711L
#define static_assert(...) __extension__ _Static_assert(__VA_ARGS__)
@@ -901,7 +902,8 @@ namespace cwg573 { // cwg573: no
void *d = reinterpret_cast<void*>(c);
// cxx98-error at -1 {{cast between pointer-to-function and pointer-to-object is an extension}}
void f() { delete a; }
- // expected-error at -1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+ // cxx98-23-error at -1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+ // since-cxx26-error at -2 {{cannot delete pointer to incomplete type 'void'}}
int n = d - a;
// expected-error at -1 {{arithmetic on pointers to void}}
// FIXME: This is ill-formed.
@@ -1238,11 +1240,13 @@ namespace cwg599 { // cwg599: partial
struct V { operator int*(); operator Fn*(); };
void f(void *p, void (*q)(), S s, T t, U u, V v) {
delete p;
- // expected-error at -1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+ // cxx98-23-error at -1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+ // since-cxx26-error at -2 {{cannot delete pointer to incomplete type 'void'}}
delete q;
// expected-error at -1 {{cannot delete expression of type 'void (*)()'}}
delete s;
- // expected-error at -1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+ // cxx98-23-error at -1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+ // since-cxx26-error at -2 {{cannot delete pointer to incomplete type 'void'}}
delete t;
// expected-error at -1 {{cannot delete expression of type 'T'}}
// FIXME: This is valid, but is rejected due to a non-conforming GNU
diff --git a/clang/test/SemaCXX/new-delete.cpp b/clang/test/SemaCXX/new-delete.cpp
index 1a99c6aac604f..ec6ad43476f94 100644
--- a/clang/test/SemaCXX/new-delete.cpp
+++ b/clang/test/SemaCXX/new-delete.cpp
@@ -1,8 +1,10 @@
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++98
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++11
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++14
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx17,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++17
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++20
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++98
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++11
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++14
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,cxx17,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++17
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++20
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++23
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,since-cxx26,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++2c
// FIXME Location is (frontend)
// cxx17-note@*:* {{candidate function not viable: requires 2 arguments, but 3 were provided}}
@@ -172,8 +174,12 @@ void bad_deletes()
{
delete 0; // expected-error {{cannot delete expression of type 'int'}}
delete [0] (int*)0; // expected-error {{expected variable name or 'this' in lambda capture list}}
- delete (void*)0; // expected-warning {{cannot delete expression with pointer-to-'void' type 'void *'}}
- delete (T*)0; // expected-warning {{deleting pointer to incomplete type}}
+ delete (void*)0;
+ // cxx98-23-warning at -1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+ // since-cxx26-error at -2 {{cannot delete pointer to incomplete type 'void'}}
+ delete (T*)0;
+ // cxx98-23-warning at -1 {{deleting pointer to incomplete type}}
+ // since-cxx26-error at -2 {{cannot delete pointer to incomplete type 'T'}}
::S::delete (int*)0; // expected-error {{expected unqualified-id}}
}
@@ -513,8 +519,10 @@ namespace DeleteIncompleteClass {
namespace DeleteIncompleteClassPointerError {
struct A; // expected-note {{forward declaration}}
- void f(A *x) { 1+delete x; } // expected-warning {{deleting pointer to incomplete type}} \
- // expected-error {{invalid operands to binary expression}}
+ void f(A *x) { 1+delete x; }
+ // expected-error at -1 {{invalid operands to binary expression}}
+ // cxx98-23-warning at -2 {{deleting pointer to incomplete type}}
+ // since-cxx26-error at -3 {{cannot delete pointer to incomplete type 'A'}}
}
namespace PR10504 {
``````````
</details>
https://github.com/llvm/llvm-project/pull/97733
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