[clang][IFS] Prevent Clang-IFS from Leaking symbols from inside a block.

[plotfi]

Summary

Built libdispatch with clang interface stubs. Ran into some block related issues. Basically VarDecl symbols can leak out because I wasn't checking the case where a VarDecl is contained inside a BlockDecl (versus a method or function).

This patch checks that a VarDecl is not a child decl of a BlockDecl.
This patch also does something very similar for c++ lambdas as well.

[plotfi]

Abandoning. Duplicate diff

clang/lib/Frontend/InterfaceStubFunctionsConsumer.cpp

auto isVisible = [](const NamedDecl *ND) -> bool {
       return ND->getVisibility() == DefaultVisibility;
     };
 
     auto ignoreDecl = [this, isVisible](const NamedDecl *ND) -> bool {
       if (!isVisible(ND))
         return true;
 
       if (const VarDecl *VD = dyn_cast<VarDecl>(ND))
+        if (const auto *Parent = VD->getParentFunctionOrMethod()) {
+          if (const auto *BD = dyn_cast_or_null<BlockDecl>(Parent))
+            return true;
+          if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Parent))
+            return true;
+        }
+
+      if (const VarDecl *VD = dyn_cast<VarDecl>(ND))
         if ((VD->getStorageClass() == StorageClass::SC_Extern) ||
             (VD->getStorageClass() == StorageClass::SC_Static &&
              VD->getParentFunctionOrMethod() == nullptr))
           return true;
 
       if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
         if (FD->isInlined() && !isa<CXXMethodDecl>(FD) &&
             !Instance.getLangOpts().GNUInline)

clang/test/InterfaceStubs/blocks.c

+// RUN: %clang_cc1 -emit-interface-stubs -fblocks -o - %s | FileCheck %s
+
+// CHECK: --- !experimental-ifs-v1
+// CHECK-NEXT: IfsVersion: 1.0
+// CHECK-NEXT: Triple:
+// CHECK-NEXT: ObjectFileFormat: ELF
+// CHECK-NEXT: Symbols:
+// CHECK-NEXT: ...
+static void (^f)(void*) = ^(void* data) { int i; };

clang/test/InterfaceStubs/lambda.cpp

+// RUN: %clang_cc1 -emit-interface-stubs -o - %s | FileCheck %s
+
+// CHECK: --- !experimental-ifs-v1
+// CHECK-NEXT: IfsVersion: 1.0
+// CHECK-NEXT: Triple:
+// CHECK-NEXT: ObjectFileFormat: ELF
+// CHECK-NEXT: Symbols:
+// CHECK-NEXT:   "f" : { Type: Object, Size: 1 }
+// CHECK-NEXT: ...
+auto f = [](void* data) { int i; };