[PATCH] D25556: [Sema] Add variable captured by a block to the enclosing lambda's potential capture list

[Akira Hatanaka via cfe-commits]

ahatanak created this revision.
ahatanak added reviewers: rsmith, rjmccall.
ahatanak added a subscriber: cfe-commits.

When compiling the following code, DoMarkVarDeclReferenced fails to capture 
variable "outerp":

  auto lambda =[&](auto p) {
    return ^{
      return p + outerp;
    }();
  };

This happens because Sema::getCurLambda() returns the lambda scope only when 
it's the last scope that has been pushed to Sema::FunctionScopes and therefore 
returns null if there is a block enclosed in the lambda. To fix this bug, this 
patch defines function Sema::getInnermostLambda() and uses it in 
DoMarkVarDeclReferenced to get the innermost lambda scope.

rdar://problem/28412462


https://reviews.llvm.org/D25556

Files:
  include/clang/Sema/Sema.h
  lib/Sema/Sema.cpp
  lib/Sema/SemaExpr.cpp
  test/SemaObjCXX/blocks.mm


Index: test/SemaObjCXX/blocks.mm
===================================================================
--- test/SemaObjCXX/blocks.mm
+++ test/SemaObjCXX/blocks.mm
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -fblocks -Wno-objc-root-class %s
+// RUN: %clang_cc1 -fsyntax-only -verify -fblocks -Wno-objc-root-class 
-std=c++14 %s
 @protocol NSObject;
 
 void bar(id(^)(void));
@@ -144,3 +144,14 @@
 
   template void f<X>(X);
 }
+
+namespace GenericLambdaCapture {
+  int test(int outerp) {
+    auto lambda =[&](auto p) {
+      return ^{
+        return p + outerp;
+      }();
+    };
+    return lambda(1);
+  }
+}
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -14013,7 +14013,7 @@
         (SemaRef.CurContext != Var->getDeclContext() &&
          Var->getDeclContext()->isFunctionOrMethod() && 
Var->hasLocalStorage());
     if (RefersToEnclosingScope) {
-      if (LambdaScopeInfo *const LSI = SemaRef.getCurLambda()) {
+      if (LambdaScopeInfo *const LSI = SemaRef.getInnermostLambda()) {
         // If a variable could potentially be odr-used, defer marking it so
         // until we finish analyzing the full expression for any
         // lvalue-to-rvalue
Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -1220,6 +1220,13 @@
   return nullptr;
 }
 
+LambdaScopeInfo *Sema::getInnermostLambda() {
+  for (auto I = FunctionScopes.rbegin(), E = FunctionScopes.rend(); I != E; 
++I)
+    if (auto LSI = dyn_cast<LambdaScopeInfo>(*I))
+      return LSI;
+
+  return nullptr;
+}
 
 void Sema::ActOnComment(SourceRange Comment) {
   if (!LangOpts.RetainCommentsFromSystemHeaders &&
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -1247,6 +1247,9 @@
   /// \brief Retrieve the current generic lambda info, if any.
   sema::LambdaScopeInfo *getCurGenericLambda();
 
+  /// Retrieve the innermost lambda scope info, if any.
+  sema::LambdaScopeInfo *getInnermostLambda();
+
   /// \brief Retrieve the current captured region, if any.
   sema::CapturedRegionScopeInfo *getCurCapturedRegion();
 



Index: test/SemaObjCXX/blocks.mm
===================================================================
--- test/SemaObjCXX/blocks.mm
+++ test/SemaObjCXX/blocks.mm
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -fblocks -Wno-objc-root-class %s
+// RUN: %clang_cc1 -fsyntax-only -verify -fblocks -Wno-objc-root-class -std=c++14 %s
 @protocol NSObject;
 
 void bar(id(^)(void));
@@ -144,3 +144,14 @@
 
   template void f<X>(X);
 }
+
+namespace GenericLambdaCapture {
+  int test(int outerp) {
+    auto lambda =[&](auto p) {
+      return ^{
+        return p + outerp;
+      }();
+    };
+    return lambda(1);
+  }
+}
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -14013,7 +14013,7 @@
         (SemaRef.CurContext != Var->getDeclContext() &&
          Var->getDeclContext()->isFunctionOrMethod() && Var->hasLocalStorage());
     if (RefersToEnclosingScope) {
-      if (LambdaScopeInfo *const LSI = SemaRef.getCurLambda()) {
+      if (LambdaScopeInfo *const LSI = SemaRef.getInnermostLambda()) {
         // If a variable could potentially be odr-used, defer marking it so
         // until we finish analyzing the full expression for any
         // lvalue-to-rvalue
Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -1220,6 +1220,13 @@
   return nullptr;
 }
 
+LambdaScopeInfo *Sema::getInnermostLambda() {
+  for (auto I = FunctionScopes.rbegin(), E = FunctionScopes.rend(); I != E; ++I)
+    if (auto LSI = dyn_cast<LambdaScopeInfo>(*I))
+      return LSI;
+
+  return nullptr;
+}
 
 void Sema::ActOnComment(SourceRange Comment) {
   if (!LangOpts.RetainCommentsFromSystemHeaders &&
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -1247,6 +1247,9 @@
   /// \brief Retrieve the current generic lambda info, if any.
   sema::LambdaScopeInfo *getCurGenericLambda();
 
+  /// Retrieve the innermost lambda scope info, if any.
+  sema::LambdaScopeInfo *getInnermostLambda();
+
   /// \brief Retrieve the current captured region, if any.
   sema::CapturedRegionScopeInfo *getCurCapturedRegion();
 

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