Basic support for name mangling of C++11 lambda expressions. Because

name mangling in the Itanium C++ ABI for lambda expressions is so
dependent on context, we encode the number used to encode each lambda
as part of the lambda closure type, and maintain this value within
Sema.

Note that there are a several pieces still missing:
  - We still get the linkage of lambda expressions wrong
  - We aren't properly numbering or mangling lambda expressions that
  occur in default function arguments or in data member initializers.
  - We aren't (de-)serializing the lambda numbering tables

llvm-svn: 150982

1 files changed, 39 insertions, 0 deletions

diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 4843716909f..a0bb6c74c33 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -122,6 +122,13 @@ public:
   }
 
   bool getNextDiscriminator(const NamedDecl *ND, unsigned &disc) {
+    // Lambda closure types with external linkage (indicated by a 
+    // non-zero lambda mangling number) have their own numbering scheme, so
+    // they do not need a discriminator.
+    if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(ND))
+      if (RD->isLambda() && RD->getLambdaManglingNumber() > 0)
+        return false;
+        
     unsigned &discriminator = Uniquifier[ND];
     if (!discriminator)
       discriminator = ++Discriminator;
@@ -1076,6 +1083,38 @@ void CXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
       break;
     }
 
+    // <unnamed-type-name> ::= <closure-type-name>
+    // 
+    // <closure-type-name> ::= Ul <lambda-sig> E [ <nonnegative number> ] _
+    // <lambda-sig> ::= <parameter-type>+   # Parameter types or 'v' for 'void'.
+    if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(TD)) {
+      if (Record->isLambda()) {
+        // FIXME: Figure out if we're in a function body, default argument,
+        // or initializer for a class member.
+        
+        Out << "Ul";
+        DeclarationName Name
+          = getASTContext().DeclarationNames.getCXXOperatorName(OO_Call);
+        const FunctionProtoType *Proto
+          = cast<CXXMethodDecl>(*Record->lookup(Name).first)->getType()->
+              getAs<FunctionProtoType>();
+        mangleBareFunctionType(Proto, /*MangleReturnType=*/false);        
+        Out << "E";
+        
+        // The number is omitted for the first closure type with a given 
+        // <lambda-sig> in a given context; it is n-2 for the nth closure type 
+        // (in lexical order) with that same <lambda-sig> and context.
+        //
+        // The AST keeps track of the number for us.
+        if (unsigned Number = Record->getLambdaManglingNumber()) {
+          if (Number > 1)
+            mangleNumber(Number - 2);
+        }
+        Out << '_';
+        break;
+      }
+    }
+        
     // Get a unique id for the anonymous struct.
     uint64_t AnonStructId = Context.getAnonymousStructId(TD);