Generate an AST for the conversion from a lambda closure type to a

block pointer that returns a block literal which captures (by copy)
the lambda closure itself. Some aspects of the block literal are left
unspecified, namely the capture variable (which doesn't actually
exist) and the body (which will be filled in by IRgen because it can't
be written as an AST).

Because we're switching to this model, this patch also eliminates
tracking the copy-initialization expression for the block capture of
the conversion function, since that information is now embedded in the
synthesized block literal. -1 side tables FTW.

llvm-svn: 151131

1 files changed, 79 insertions, 10 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index a1a952b833f..22fb8cb7a83 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -8755,9 +8755,9 @@ bool Sema::isImplicitlyDeleted(FunctionDecl *FD) {
 /// \brief Mark the call operator of the given lambda closure type as "used".
 static void markLambdaCallOperatorUsed(Sema &S, CXXRecordDecl *Lambda) {
   CXXMethodDecl *CallOperator 
-  = cast<CXXMethodDecl>(
-      *Lambda->lookup(
-        S.Context.DeclarationNames.getCXXOperatorName(OO_Call)).first);
+    = cast<CXXMethodDecl>(
+        *Lambda->lookup(
+          S.Context.DeclarationNames.getCXXOperatorName(OO_Call)).first);
   CallOperator->setReferenced();
   CallOperator->setUsed();
 }
@@ -8805,14 +8805,21 @@ void Sema::DefineImplicitLambdaToBlockPointerConversion(
        SourceLocation CurrentLocation,
        CXXConversionDecl *Conv) 
 {
+  CXXRecordDecl *Lambda = Conv->getParent();
+  
   // Make sure that the lambda call operator is marked used.
-  markLambdaCallOperatorUsed(*this, Conv->getParent());
+  CXXMethodDecl *CallOperator 
+    = cast<CXXMethodDecl>(
+        *Lambda->lookup(
+          Context.DeclarationNames.getCXXOperatorName(OO_Call)).first);
+  CallOperator->setReferenced();
+  CallOperator->setUsed();
   Conv->setUsed();
   
   ImplicitlyDefinedFunctionScope Scope(*this, Conv);
   DiagnosticErrorTrap Trap(Diags);
   
-  // Copy-initialize the lambda object as needed to capture
+  // Copy-initialize the lambda object as needed to capture it.
   Expr *This = ActOnCXXThis(CurrentLocation).take();
   Expr *DerefThis =CreateBuiltinUnaryOp(CurrentLocation, UO_Deref, This).take();
   ExprResult Init = PerformCopyInitialization(
@@ -8823,16 +8830,78 @@ void Sema::DefineImplicitLambdaToBlockPointerConversion(
   if (!Init.isInvalid())
     Init = ActOnFinishFullExpr(Init.take());
   
-  if (!Init.isInvalid())
-    Conv->setLambdaToBlockPointerCopyInit(Init.take());
-  else {
+  if (Init.isInvalid()) {
     Diag(CurrentLocation, diag::note_lambda_to_block_conv);
+    Conv->setInvalidDecl();
+    return;
   }
   
-  // Introduce a bogus body, which IR generation will override anyway.
-  Conv->setBody(new (Context) CompoundStmt(Context, 0, 0, Conv->getLocation(),
+  // Create the new block to be returned.
+  BlockDecl *Block = BlockDecl::Create(Context, Conv, Conv->getLocation());
+  
+  // Set the type information.
+  Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
+  Block->setIsVariadic(CallOperator->isVariadic());
+  Block->setBlockMissingReturnType(false);
+  
+  // Add parameters.
+  SmallVector<ParmVarDecl *, 4> BlockParams;
+  for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
+    ParmVarDecl *From = CallOperator->getParamDecl(I);
+    BlockParams.push_back(ParmVarDecl::Create(Context, Block,
+                                              From->getLocStart(),
+                                              From->getLocation(),
+                                              From->getIdentifier(),
+                                              From->getType(),
+                                              From->getTypeSourceInfo(),
+                                              From->getStorageClass(),
+                                            From->getStorageClassAsWritten(),
+                                              /*DefaultArg=*/0));
+  }
+  Block->setParams(BlockParams);
+  
+  // Add capture. The capture is uses a fake (NULL) variable, since we don't
+  // actually want to have to name a capture variable. However, the 
+  // initializer copy-initializes the lambda object.
+  BlockDecl::Capture Capture(/*Variable=*/0, /*ByRef=*/false, /*Nested=*/false,
+                             /*Copy=*/Init.take());
+  Block->setCaptures(Context, &Capture, &Capture + 1, 
+                     /*CapturesCXXThis=*/false);
+  
+  // Add a fake function body to the block. IR generation is responsible
+  // for filling in the actual body, which cannot be expressed as an AST.
+  Block->setBody(new (Context) CompoundStmt(Context, 0, 0, 
+                                            Conv->getLocation(),
+                                            Conv->getLocation()));
+
+  // Create the block literal expression.
+  Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
+  ExprCleanupObjects.push_back(Block);
+  ExprNeedsCleanups = true;
+
+  // If we're not under ARC, make sure we still get the _Block_copy/autorelease
+  // behavior.
+  if (!getLangOptions().ObjCAutoRefCount)
+    BuildBlock = ImplicitCastExpr::Create(Context, BuildBlock->getType(),
+                                          CK_CopyAndAutoreleaseBlockObject,
+                                          BuildBlock, 0, VK_RValue);
+  
+  // Create the return statement that returns the block from the conversion
+  // function.
+  StmtResult Return = ActOnReturnStmt(Conv->getLocation(), BuildBlock);
+  if (Return.isInvalid()) {
+    Diag(CurrentLocation, diag::note_lambda_to_block_conv);
+    Conv->setInvalidDecl();
+    return;
+  }
+
+  // Set the body of the conversion function.
+  Stmt *ReturnS = Return.take();
+  Conv->setBody(new (Context) CompoundStmt(Context, &ReturnS, 1, 
+                                           Conv->getLocation(), 
                                            Conv->getLocation()));
   
+  // We're done; notify the mutation listener, if any.
   if (ASTMutationListener *L = getASTMutationListener()) {
     L->CompletedImplicitDefinition(Conv);
   }