Make Clang complain about taking the address of an unqualified member function. Fixes PR5985.

llvm-svn: 93150

3 files changed, 31 insertions, 2 deletions

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 7d668a0ffea..da94a21452e 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1661,6 +1661,8 @@ def err_static_block_func : Error<
 def err_typecheck_address_of : Error<"address of %0 requested">;
 def ext_typecheck_addrof_void : Extension<
   "ISO C forbids taking the address of an expression of type 'void'">;
+def err_unqualified_pointer_member_function : Error<
+  "must explicitly qualify member function %0 when taking its address">;
 def err_typecheck_invalid_lvalue_addrof : Error<
   "address expression must be an lvalue or a function designator">;
 def err_typecheck_unary_expr : Error<
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index f1311098336..bf9d099e560 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -5872,7 +5872,22 @@ QualType Sema::CheckAddressOfOperand(Expr *op, SourceLocation OpLoc) {
   NamedDecl *dcl = getPrimaryDecl(op);
   Expr::isLvalueResult lval = op->isLvalue(Context);
 
-  if (lval != Expr::LV_Valid && lval != Expr::LV_IncompleteVoidType) {
+  MemberExpr *ME = dyn_cast<MemberExpr>(op);
+  if (lval == Expr::LV_MemberFunction && ME &&
+      isa<CXXMethodDecl>(ME->getMemberDecl())) {
+    ValueDecl *dcl = cast<MemberExpr>(op)->getMemberDecl();
+    // &f where f is a member of the current object, or &o.f, or &p->f
+    // All these are not allowed, and we need to catch them before the dcl
+    // branch of the if, below.
+    Diag(OpLoc, diag::err_unqualified_pointer_member_function)
+        << dcl;
+    // FIXME: Improve this diagnostic and provide a fixit.
+
+    // Now recover by acting as if the function had been accessed qualified.
+    return Context.getMemberPointerType(op->getType(),
+                Context.getTypeDeclType(cast<RecordDecl>(dcl->getDeclContext()))
+                       .getTypePtr());
+  } else if (lval != Expr::LV_Valid && lval != Expr::LV_IncompleteVoidType) {
     // C99 6.5.3.2p1
     // The operand must be either an l-value or a function designator
     if (!op->getType()->isFunctionType()) {
diff --git a/clang/test/SemaCXX/member-pointer.cpp b/clang/test/SemaCXX/member-pointer.cpp
index 65d05eb5af7..3d9d5b5ebbb 100644
--- a/clang/test/SemaCXX/member-pointer.cpp
+++ b/clang/test/SemaCXX/member-pointer.cpp
@@ -80,7 +80,7 @@ void g() {
 
   void (HasMembers::*pmf)() = &HasMembers::f;
   void (*pnf)() = &Fake::f;
-  &hm.f; // FIXME: needs diagnostic expected-warning{{result unused}}
+  &hm.f; // expected-error {{must explicitly qualify}} expected-warning{{result unused}}
 
   void (HasMembers::*pmgv)() = &HasMembers::g;
   void (HasMembers::*pmgi)(int) = &HasMembers::g;
@@ -136,3 +136,15 @@ void i() {
   OverloadsPtrMem m;
   int foo = m->*"Awesome!";
 }
+
+namespace pr5985 {
+  struct c {
+    void h();
+    void f() {
+      void (c::*p)();
+      p = &h; // expected-error {{must explicitly qualify}}
+      p = &this->h; // expected-error {{must explicitly qualify}}
+      p = &(*this).h; // expected-error {{must explicitly qualify}}
+    }
+  };
+}