[PATCH] D11848: AST: Implement mangling support for function types without a prototype.

[Peter Collingbourne via cfe-commits]

pcc added inline comments.

================
Comment at: lib/AST/ItaniumMangle.cpp:2060-2062
@@ -2058,2 +2059,5 @@
 void CXXNameMangler::mangleType(const FunctionNoProtoType *T) {
-  llvm_unreachable("Can't mangle K&R function prototypes");
+  // Function types without prototypes can arise when mangling a function type
+  // within an overloadable function in C. We mangle these as we do a function
+  // with an empty variadic argument list in C++.
+  Out << 'F';
----------------
rsmith wrote:
> This seems like a suboptimal mangling; a no-prototype function type is not compatible with a varargs function type, and in particular may have a different calling convention across a C/C++ ABI boundary. How about instead mangling this as the absence of any parameter types? (That is, drop the `z`, and mangle your testcase below as just `_Z1fPFvzE`.) libc++abi already demangles that as desired (but libstdc++ considers it an invalid mangled name).
Do you mean `_Z1fPFvE`? Sounds reasonable to me. I guess on the MS side we can use `@` instead of `Z` to create the distinction there.


http://reviews.llvm.org/D11848