[clang] [clang] pointer to member with qualified-id enclosed in parentheses in unevaluated context should be invalid (PR #89713)

via cfe-commits cfe-commits at lists.llvm.org
Wed May 1 23:19:19 PDT 2024


https://github.com/zwuis updated https://github.com/llvm/llvm-project/pull/89713

>From f6fd1e5e5f42b3c72cb5aeaf9e6d4e91d5424bee Mon Sep 17 00:00:00 2001
From: YanzuoLiu <zwuis at outlook.com>
Date: Tue, 23 Apr 2024 14:56:12 +0800
Subject: [PATCH 1/6] Add missing check when making pointer to member

---
 clang/lib/Sema/SemaExpr.cpp                    | 11 +++++++++++
 .../CXX/expr/expr.unary/expr.unary.op/p3.cpp   | 18 +++++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 5c861467bc1023..824667fb722365 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14644,6 +14644,17 @@ QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
             return QualType();
           }
 
+          // C++11 [expr.unary.op] p4:
+          // A pointer to member is only formed when an explicit & is used and
+          // its operand is a qualified-id not enclosed in parentheses.
+          if (isa<ParenExpr>(OrigOp.get())) {
+            // `op->getEndLoc()` is the last part of the qualified-id.
+            // For example, "baz" in "foo::bar::baz".
+            Diag(op->getEndLoc(), diag::err_invalid_non_static_member_use)
+                << dcl->getDeclName() << op->getSourceRange();
+            return QualType();
+          }
+
           while (cast<RecordDecl>(Ctx)->isAnonymousStructOrUnion())
             Ctx = Ctx->getParent();
 
diff --git a/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp b/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
index 08ab0ca56fb632..73d850a6839da7 100644
--- a/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
+++ b/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 -fsyntax-only %s -verify 
-// expected-no-diagnostics
 
 namespace rdar10544564 {
   // Check that we don't attempt to use an overloaded operator& when
@@ -27,3 +26,20 @@ namespace rdar10544564 {
   X (Y::*func_mem_ptr1)() = &Y::memfunc1;
   X (Y::*func_mem_ptr2)() = &Y::memfunc2;
 }
+
+namespace test2 {
+  struct A {
+    int val;
+    void func() {}
+  };
+
+  void test() {
+    decltype(&(A::val)) ptr1; // expected-error {{invalid use of non-static data member 'val'}}
+    int A::* ptr2 = &(A::val); // expected-error {{invalid use of non-static data member 'val'}}
+
+    // FIXME: Error messages in these cases are less than clear, we can do
+    // better.
+    int size = sizeof(&(A::func)); // expected-error {{call to non-static member function without an object argument}}
+    void (A::* ptr3)() = &(A::func); // expected-error {{call to non-static member function without an object argument}}
+  }
+}

>From 22b18d32d79e5dcd0390aa17c454f373e565868a Mon Sep 17 00:00:00 2001
From: YanzuoLiu <zwuis at outlook.com>
Date: Wed, 24 Apr 2024 17:21:14 +0800
Subject: [PATCH 2/6] Apply suggestion from cor3ntin

Co-authored-by: cor3ntin <corentinjabot at gmail.com>
---
 clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp b/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
index 73d850a6839da7..3e99b333d0e584 100644
--- a/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
+++ b/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
@@ -27,7 +27,7 @@ namespace rdar10544564 {
   X (Y::*func_mem_ptr2)() = &Y::memfunc2;
 }
 
-namespace test2 {
+namespace GH40906 {
   struct A {
     int val;
     void func() {}

>From 81fd55780b34c92566bdfb7fc1a2cde690675d66 Mon Sep 17 00:00:00 2001
From: YanzuoLiu <zwuis at outlook.com>
Date: Wed, 24 Apr 2024 17:39:45 +0800
Subject: [PATCH 3/6] Move tests to the right place

---
 .../CXX/expr/expr.unary/expr.unary.op/p3.cpp   | 18 +-----------------
 .../CXX/expr/expr.unary/expr.unary.op/p4.cpp   | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp b/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
index 3e99b333d0e584..08ab0ca56fb632 100644
--- a/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
+++ b/clang/test/CXX/expr/expr.unary/expr.unary.op/p3.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only %s -verify 
+// expected-no-diagnostics
 
 namespace rdar10544564 {
   // Check that we don't attempt to use an overloaded operator& when
@@ -26,20 +27,3 @@ namespace rdar10544564 {
   X (Y::*func_mem_ptr1)() = &Y::memfunc1;
   X (Y::*func_mem_ptr2)() = &Y::memfunc2;
 }
-
-namespace GH40906 {
-  struct A {
-    int val;
-    void func() {}
-  };
-
-  void test() {
-    decltype(&(A::val)) ptr1; // expected-error {{invalid use of non-static data member 'val'}}
-    int A::* ptr2 = &(A::val); // expected-error {{invalid use of non-static data member 'val'}}
-
-    // FIXME: Error messages in these cases are less than clear, we can do
-    // better.
-    int size = sizeof(&(A::func)); // expected-error {{call to non-static member function without an object argument}}
-    void (A::* ptr3)() = &(A::func); // expected-error {{call to non-static member function without an object argument}}
-  }
-}
diff --git a/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp b/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp
index 537d676738bef8..a9efbb38859c5d 100644
--- a/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp
+++ b/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp
@@ -41,3 +41,20 @@ namespace test2 {
     int (A::*ptr)(int) = &(A::foo); // expected-error {{cannot create a non-constant pointer to member function}}
   }
 }
+
+namespace GH40906 {
+  struct A {
+    int val;
+    void func() {}
+  };
+
+  void test() {
+    decltype(&(A::val)) ptr1; // expected-error {{invalid use of non-static data member 'val'}}
+    int A::* ptr2 = &(A::val); // expected-error {{invalid use of non-static data member 'val'}}
+
+    // FIXME: Error messages in these cases are less than clear, we can do
+    // better.
+    int size = sizeof(&(A::func)); // expected-error {{call to non-static member function without an object argument}}
+    void (A::* ptr3)() = &(A::func); // expected-error {{call to non-static member function without an object argument}}
+  }
+}

>From 5fb8cd8220dc9d8210517eadcd6b827a141fd78f Mon Sep 17 00:00:00 2001
From: YanzuoLiu <zwuis at outlook.com>
Date: Thu, 25 Apr 2024 11:32:02 +0800
Subject: [PATCH 4/6] Make diagnostic message more clear

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td  |  3 +++
 clang/lib/Sema/SemaExpr.cpp                       | 15 ++++++++++-----
 .../test/CXX/expr/expr.unary/expr.unary.op/p4.cpp |  2 +-
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 63e951daec7477..3bec69d8a5285d 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -7511,6 +7511,9 @@ def err_nested_non_static_member_use : Error<
 def warn_cxx98_compat_non_static_member_use : Warning<
   "use of non-static data member %0 in an unevaluated context is "
   "incompatible with C++98">, InGroup<CXX98Compat>, DefaultIgnore;
+def err_form_ptr_to_member_from_parenthesized_expr : Error<
+  "cannot form pointer to member from a parenthesized expression; "
+  "did you mean to remove the parentheses?">;
 def err_invalid_incomplete_type_use : Error<
   "invalid use of incomplete type %0">;
 def err_builtin_func_cast_more_than_one_arg : Error<
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 824667fb722365..f07a422041dae2 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14648,11 +14648,16 @@ QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
           // A pointer to member is only formed when an explicit & is used and
           // its operand is a qualified-id not enclosed in parentheses.
           if (isa<ParenExpr>(OrigOp.get())) {
-            // `op->getEndLoc()` is the last part of the qualified-id.
-            // For example, "baz" in "foo::bar::baz".
-            Diag(op->getEndLoc(), diag::err_invalid_non_static_member_use)
-                << dcl->getDeclName() << op->getSourceRange();
-            return QualType();
+            SourceLocation LeftParenLoc = OrigOp.get()->getBeginLoc(),
+                           RightParenLoc = OrigOp.get()->getEndLoc();
+
+            Diag(LeftParenLoc,
+                 diag::err_form_ptr_to_member_from_parenthesized_expr)
+                << OrigOp.get()->getSourceRange()
+                << FixItHint::CreateRemoval(LeftParenLoc)
+                << FixItHint::CreateRemoval(RightParenLoc);
+
+            // Continuing might lead to better error recovery.
           }
 
           while (cast<RecordDecl>(Ctx)->isAnonymousStructOrUnion())
diff --git a/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp b/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp
index a9efbb38859c5d..162d59439d08ee 100644
--- a/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp
+++ b/clang/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp
@@ -49,7 +49,7 @@ namespace GH40906 {
   };
 
   void test() {
-    decltype(&(A::val)) ptr1; // expected-error {{invalid use of non-static data member 'val'}}
+    decltype(&(A::val)) ptr1; // expected-error {{cannot form pointer to member from a parenthesized expression; did you mean to remove the parentheses?}}
     int A::* ptr2 = &(A::val); // expected-error {{invalid use of non-static data member 'val'}}
 
     // FIXME: Error messages in these cases are less than clear, we can do

>From 97f0fbab28c56b466c16313bc55cabca156f02b0 Mon Sep 17 00:00:00 2001
From: YanzuoLiu <zwuis at outlook.com>
Date: Thu, 25 Apr 2024 15:34:22 +0800
Subject: [PATCH 5/6] Expand source range in diagnostic so that `&` can be
 included

---
 clang/lib/Sema/SemaExpr.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index f07a422041dae2..29aec8d373db9f 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14653,7 +14653,7 @@ QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
 
             Diag(LeftParenLoc,
                  diag::err_form_ptr_to_member_from_parenthesized_expr)
-                << OrigOp.get()->getSourceRange()
+                << SourceRange(OpLoc, RightParenLoc)
                 << FixItHint::CreateRemoval(LeftParenLoc)
                 << FixItHint::CreateRemoval(RightParenLoc);
 

>From 68b77dfab3433e68596967c13f9df0ca77d6a0fd Mon Sep 17 00:00:00 2001
From: YanzuoLiu <zwuis at outlook.com>
Date: Thu, 2 May 2024 14:19:01 +0800
Subject: [PATCH 6/6] Add a release note

---
 clang/docs/ReleaseNotes.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index f339fab6e8428f..bf87849fba2701 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -48,6 +48,8 @@ C++ Specific Potentially Breaking Changes
 - Clang now diagnoses function/variable templates that shadow their own template parameters, e.g. ``template<class T> void T();``.
   This error can be disabled via `-Wno-strict-primary-template-shadow` for compatibility with previous versions of clang.
 
+- Clang now rejects pointer to member from parenthesized expression in unevaluated context such as ``decltype(&(foo::bar))``. (#GH40906).
+
 ABI Changes in This Version
 ---------------------------
 - Fixed Microsoft name mangling of implicitly defined variables used for thread



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