PR13575: Fix USR mangling for functions taking function pointers as arguments.

[arphaman]

lib/Index/USRGeneration.cpp

757–759

I believe you can drop the '(' and ')'. The '#' should be enough to prevent the USR collision.

[jkorous-apple]

added another test

[jkorous-apple]

lib/Index/USRGeneration.cpp

757–759

Actually, this is a great question!

I was worried it might not be the case so I created two more test cases.
Let's try to imagine there are no parentheses in those USRs.
First two test cases could be solved by using 'v' or something for functions taking no arguments. But 3rd and 4th test cases would definitely need some disambiguation then.

I am not saying this is the only possible way how to represent function pointers but for proposed solution those parentheses are needed.

[arphaman]

LGTM.

lib/Index/USRGeneration.cpp

#include "clang/Basic/OpenCLImageTypes.def"
     if (const ReferenceType *RT = T->getAs<ReferenceType>()) {
       Out << '&';
       T = RT->getPointeeType();
       continue;
     }
     if (const FunctionProtoType *FT = T->getAs<FunctionProtoType>()) {
       Out << 'F';
       VisitType(FT->getReturnType());
-      for (const auto &I : FT->param_types())
+      Out << '(';
+      for (const auto &I : FT->param_types()) {
+        Out << '#';
         VisitType(I);
+      }
+      Out << ')';
       if (FT->isVariadic())
         Out << '.';
       return;
     }
     if (const BlockPointerType *BT = T->getAs<BlockPointerType>()) {
       Out << 'B';
       T = BT->getPointeeType();
       continue;

test/Index/USR/func-type.cpp

+// RUN: c-index-test core -print-source-symbols -- %s | FileCheck %s
+
+// Functions taking function pointer parameters with different signatures should result in unique USRs.
+
+typedef void (*_VoidToVoidPtr_)();
+typedef void (*_IntToVoidPtr_)( int );
+typedef _VoidToVoidPtr_ (*IntTo_VoidToVoidPtr_Ptr)( int );
+typedef _IntToVoidPtr_ (*VoidTo_IntToVoidPtr_Ptr)();
+
+void Func( IntTo_VoidToVoidPtr_Ptr );
+// CHECK: {{[0-9]+}}:6 | function/C | Func | c:@F@Func#*F*Fv()(#I)# |
+void Func( VoidTo_IntToVoidPtr_Ptr );
+// CHECK: {{[0-9]+}}:6 | function/C | Func | c:@F@Func#*F*Fv(#I)()# |
+
+void Func( void (* (*)(int, int))(int, int) );
+// CHECK: {{[0-9]+}}:6 | function/C | Func | c:@F@Func#*F*Fv(#I#I)(#I#I)# |
+void Func( void (* (*)(int, int, int))(int) );
+// CHECK: {{[0-9]+}}:6 | function/C | Func | c:@F@Func#*F*Fv(#I)(#I#I#I)# |