Sema: Add a flag for rejecting member pointers with incomplete base types.

Codebases that need to be compatible with the Microsoft ABI can pass
this flag to avoid issues caused by the lack of a fixed ABI for
incomplete member pointers.

Differential Revision: https://reviews.llvm.org/D47503

llvm-svn: 333498

8 files changed, 51 insertions, 5 deletions

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 1fa66cbcfc7..b4d76ba9183 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6350,6 +6350,8 @@ def err_bad_memptr_rhs : Error<
 def err_bad_memptr_lhs : Error<
   "left hand operand to %0 must be a %select{|pointer to }1class "
   "compatible with the right hand operand, but is %2">;
+def err_memptr_incomplete : Error<
+  "member pointer has incomplete base type %0">;
 def warn_exception_caught_by_earlier_handler : Warning<
   "exception of type %0 will be caught by earlier handler">,
   InGroup<Exceptions>;
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 654b755f672..8605286f28c 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -247,6 +247,10 @@ ENUM_LANGOPT(AddressSpaceMapMangling , AddrSpaceMapMangling, 2, ASMM_Target, "Op
 LANGOPT(IncludeDefaultHeader, 1, 0, "Include default header file for OpenCL")
 BENIGN_LANGOPT(DelayedTemplateParsing , 1, 0, "delayed template parsing")
 LANGOPT(BlocksRuntimeOptional , 1, 0, "optional blocks runtime")
+LANGOPT(
+    CompleteMemberPointers, 1, 0,
+    "Require member pointer base types to be complete at the point where the "
+    "type's inheritance model would be determined under the Microsoft ABI")
 
 ENUM_LANGOPT(GC, GCMode, 2, NonGC, "Objective-C Garbage Collection mode")
 ENUM_LANGOPT(ValueVisibilityMode, Visibility, 3, DefaultVisibility,
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index bc27844b72e..ed255c97ab9 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -782,6 +782,12 @@ def fcomment_block_commands : CommaJoined<["-"], "fcomment-block-commands=">, Gr
 def fparse_all_comments : Flag<["-"], "fparse-all-comments">, Group<f_clang_Group>, Flags<[CC1Option]>;
 def fcommon : Flag<["-"], "fcommon">, Group<f_Group>;
 def fcompile_resource_EQ : Joined<["-"], "fcompile-resource=">, Group<f_Group>;
+def fcomplete_member_pointers : Flag<["-"], "fcomplete-member-pointers">, Group<f_clang_Group>,
+   Flags<[CoreOption, CC1Option]>,
+   HelpText<"Require member pointer base types to be complete if they would be significant under the Microsoft ABI">;
+def fno_complete_member_pointers : Flag<["-"], "fno-complete-member-pointers">, Group<f_clang_Group>,
+   Flags<[CoreOption]>,
+   HelpText<"Do not require member pointer base types to be complete if they would be significant under the Microsoft ABI">;
 def fconstant_cfstrings : Flag<["-"], "fconstant-cfstrings">, Group<f_Group>;
 def fconstant_string_class_EQ : Joined<["-"], "fconstant-string-class=">, Group<f_Group>;
 def fconstexpr_depth_EQ : Joined<["-"], "fconstexpr-depth=">, Group<f_Group>;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 2c0fc4e7e3d..2347cfebf0b 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4784,6 +4784,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back("-fforce-enable-int128");
   }
 
+  if (Args.hasFlag(options::OPT_fcomplete_member_pointers,
+                   options::OPT_fno_complete_member_pointers, false))
+    CmdArgs.push_back("-fcomplete-member-pointers");
+
   // Finally add the compile command to the compilation.
   if (Args.hasArg(options::OPT__SLASH_fallback) &&
       Output.getType() == types::TY_Object &&
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 75d6a26cdb7..594164332ec 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2754,6 +2754,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
           << A->getAsString(Args) << A->getValue();
     }
   }
+
+  Opts.CompleteMemberPointers = Args.hasArg(OPT_fcomplete_member_pointers);
 }
 
 static bool isStrictlyPreprocessorAction(frontend::ActionKind Action) {
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 7e8f9b19e3d..b5a90af39ba 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -7585,11 +7585,17 @@ bool Sema::RequireCompleteTypeImpl(SourceLocation Loc, QualType T,
   //  assert(!T->isDependentType() &&
   //         "Can't ask whether a dependent type is complete");
 
-  // We lock in the inheritance model once somebody has asked us to ensure
-  // that a pointer-to-member type is complete.
-  if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
-    if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>()) {
-      if (!MPTy->getClass()->isDependentType()) {
+  if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>()) {
+    if (!MPTy->getClass()->isDependentType()) {
+      if (getLangOpts().CompleteMemberPointers &&
+          !MPTy->getClass()->getAsCXXRecordDecl()->isBeingDefined() &&
+          RequireCompleteType(Loc, QualType(MPTy->getClass(), 0),
+                              diag::err_memptr_incomplete))
+        return true;
+
+      // We lock in the inheritance model once somebody has asked us to ensure
+      // that a pointer-to-member type is complete.
+      if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
         (void)isCompleteType(Loc, QualType(MPTy->getClass(), 0));
         assignInheritanceModel(*this, MPTy->getMostRecentCXXRecordDecl());
       }
diff --git a/clang/test/Driver/complete-member-pointers.cpp b/clang/test/Driver/complete-member-pointers.cpp
new file mode 100644
index 00000000000..6fde2e7a0ef
--- /dev/null
+++ b/clang/test/Driver/complete-member-pointers.cpp
@@ -0,0 +1,7 @@
+// RUN: %clangxx -### -c %s -o %t.o -target x86_64-unknown-linux 2>&1 | FileCheck --check-prefix=NOFLAG %s
+// RUN: %clangxx -### -c %s -o %t.o -target x86_64-unknown-linux -fcomplete-member-pointers 2>&1 | FileCheck %s
+// RUN: %clangxx -### -c %s -o %t.o -target x86_64-unknown-linux -fcomplete-member-pointers -fno-complete-member-pointers 2>&1 | FileCheck --check-prefix=NOFLAG %s
+// RUN: %clang_cl -### /c %s /Fo%t.o -target x86_64-pc-win32 -fcomplete-member-pointers 2>&1 | FileCheck %s
+
+// CHECK: "-fcomplete-member-pointers"
+// NOFLAG-NOT: "-fcomplete-member-pointers"
diff --git a/clang/test/SemaCXX/complete-member-pointers.cpp b/clang/test/SemaCXX/complete-member-pointers.cpp
new file mode 100644
index 00000000000..942bb703a92
--- /dev/null
+++ b/clang/test/SemaCXX/complete-member-pointers.cpp
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -verify -fsyntax-only -fcomplete-member-pointers %s
+
+struct S; // expected-note {{forward declaration of 'S'}}
+typedef int S::*t;
+t foo; // expected-error {{member pointer has incomplete base type 'S'}}
+
+struct S2 {
+  int S2::*foo;
+};
+int S2::*bar;
+
+template <typename T>
+struct S3 {
+  int T::*foo;
+};