[clang] b9f7678 - [Clang] Fix lambda CheckForDefaultedFunction(...) so that it checks the CXXMethodDecl is a special member function before attempting to call DefineDefaultedFunction(...)

[Shafik Yaghmour via cfe-commits]

Author: Shafik Yaghmour
Date: 2022-08-30T18:08:44-07:00
New Revision: b9f767884669db0b5a56d87b0e8733614d8f884d

URL: https://github.com/llvm/llvm-project/commit/b9f767884669db0b5a56d87b0e8733614d8f884d
DIFF: https://github.com/llvm/llvm-project/commit/b9f767884669db0b5a56d87b0e8733614d8f884d.diff

LOG: [Clang] Fix lambda CheckForDefaultedFunction(...) so that it checks the CXXMethodDecl is a special member function before attempting to call DefineDefaultedFunction(...)

In Sema::CheckCompletedCXXClass(...) It used a lambda CheckForDefaultedFunction
the CXXMethodDecl passed to CheckForDefaultedFunction may not be a special
member function and so before attempting to apply functions that only apply to
special member functions it needs to check. It fails to do this before calling
DefineDefaultedFunction(...). This PR adds that check and test to verify we no
longer crash.

This fixes https://github.com/llvm/llvm-project/issues/57431

Differential Revision: https://reviews.llvm.org/D132906

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Sema/SemaDeclCXX.cpp
    clang/test/SemaCXX/constant-expression-cxx2a.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index f946018b361c..944d88d23017 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -86,6 +86,9 @@ Bug Fixes
   `Issue 57387 <https://github.com/llvm/llvm-project/issues/57387>`_.
 - Fix a crash when emitting a concept-related diagnostic. This fixes
   `Issue 57415 <https://github.com/llvm/llvm-project/issues/57415>`_.
+- Fix a crash when attempting to default a virtual constexpr non-special member
+  function in a derived class. This fixes
+  `Issue 57431 <https://github.com/llvm/llvm-project/issues/57431>`_
 
 
 Improvements to Clang's diagnostics

diff  --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 198de680ae3d..04d06c11e9c0 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -6954,7 +6954,8 @@ void Sema::CheckCompletedCXXClass(Scope *S, CXXRecordDecl *Record) {
     // Define defaulted constexpr virtual functions that override a base class
     // function right away.
     // FIXME: We can defer doing this until the vtable is marked as used.
-    if (M->isDefaulted() && M->isConstexpr() && M->size_overridden_methods())
+    if (CSM != CXXInvalid && M->isDefaulted() && M->isConstexpr() &&
+        M->size_overridden_methods())
       DefineDefaultedFunction(*this, M, M->getLocation());
 
     if (!Incomplete)

diff  --git a/clang/test/SemaCXX/constant-expression-cxx2a.cpp b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
index 6ebec5dc7e30..63ea42995582 100644
--- a/clang/test/SemaCXX/constant-expression-cxx2a.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
@@ -1473,3 +1473,13 @@ namespace PR45879 {
   }
   static_assert(g()); // expected-error {{constant expression}} expected-note {{in call}}
 }
+
+namespace GH57431 {
+class B {
+  virtual int constexpr f() = 0;
+};
+
+class D : B {
+  virtual int constexpr f() = default; // expected-error {{only special member functions and comparison operators may be defaulted}}
+};
+}