[MS ABI] Implement more of the Itanium mangling rules

[majnemer]

Summary

We didn't implement one of the corner cases: a lambda which belongs to
an initializer for a field. In this case, we need to mangle the field
name into the lambda.

This fixes PR31197.

[rnk]

test/CodeGenCXX/mangle-ms-cxx11.cpp

337

This machinery is also supposed to kick in for lambdas in default arguments, right? Can you add that test case?

[majnemer]

• Address review comments

[rnk]

lib/AST/MicrosoftMangle.cpp

835

Isn't this no good if I have two lambdas in one default arg?

inline int f(int x = [] { return 1; }() + [] { return 2; }()) { return x; }
int main() { return f(); }

We probably need <lambda_${argno}_${id}>. =/

[majnemer]

• Address review comments

[majnemer]

• Simplify the mangling a little bit

[rnk]

lgtm Thanks, apologies for the scope creep.

lib/AST/MicrosoftMangle.cpp

case DeclarationName::Identifier: {
                "Typedef was not named!");
         mangleSourceName(D->getDeclName().getAsIdentifierInfo()->getName());
         break;
       }
 
       if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(TD)) {
         if (Record->isLambda()) {
           llvm::SmallString<10> Name("<lambda_");
+          unsigned LambdaManglingNumber = Record->getLambdaManglingNumber();
           unsigned LambdaId;
-          if (Record->getLambdaManglingNumber())
-            LambdaId = Record->getLambdaManglingNumber();
+          if (LambdaManglingNumber)
+            LambdaId = LambdaManglingNumber;
           else
             LambdaId = Context.getLambdaId(Record);
 
           Name += llvm::utostr(LambdaId);
           Name += ">";
 
           mangleSourceName(Name);
+
+          // If the context of a closure type is an initializer for a class
+          // member (static or nonstatic), it is encoded in a qualified name.
+          if (LambdaManglingNumber) {
+            if (Decl *Context = Record->getLambdaContextDecl()) {
+              if ((isa<VarDecl>(Context) || isa<FieldDecl>(Context)) &&
+                  Context->getDeclContext()->isRecord()) {
+                mangleUnqualifiedName(cast<NamedDecl>(Context));
+              }
+            }
+          }
           break;
         }
       }
 
       llvm::SmallString<64> Name("<unnamed-type-");
       if (DeclaratorDecl *DD =
               Context.getASTContext().getDeclaratorForUnnamedTagDecl(TD)) {
         // Anonymous types without a name for linkage purposes have their

test/CodeGenCXX/mangle-ms-cxx11.cpp

 // __unaligned qualifier for function types
 struct unaligned_foo8_S {
     void unaligned_foo8() volatile __unaligned;
 };
 void unaligned_foo8_S::unaligned_foo8() volatile __unaligned {}
 
 // CHECK-DAG: @"\01?unaligned_foo8@unaligned_foo8_S@@QFCEXXZ"
 
+namespace PR31197 {
+struct A {
+  // CHECK-DAG: define linkonce_odr x86_thiscallcc i32* @"\01??R<lambda_1>@x@A@PR31197@@QBE@XZ"(
+  int *x = []() {
+    static int white;
+    // CHECK-DAG: @"\01?white@?1???R<lambda_1>@x@A@PR31197@@QBE@XZ@4HA"
+    return &white;
+  }();
+  // CHECK-DAG: define linkonce_odr x86_thiscallcc i32* @"\01??R<lambda_1>@y@A@PR31197@@QBE@XZ"(
+  int *y = []() {
+    static int black;
+    // CHECK-DAG: @"\01?black@?1???R<lambda_1>@y@A@PR31197@@QBE@XZ@4HA"
+    return &black;
+  }();
+};
+A a;
+}