Bug 22489 – C header generation ignores custom mangling

```d import std.traits : Parameters; class Type { this() {} } pragma(msg, creator.mangleof); // _D9onlineapp7creatorFZPv pragma(mangle, "create_" ~ __traits(identifier, Type)) export extern(C) void* creator(Parameters!(Type.__ctor) args) { pragma(msg, creator.mangleof); // create_Type return cast(void*)(new Type(args)); } pragma(msg, creator.mangleof); // create_Type ``` The assembly for creator is create_Type but with -HC it is being generated as creator.

`extern(C)` functions should just be exported by using the custom mangle as the identifier. `extern(C++)` functions probably need to be ignored because C++ doesn't have something like `pragma(mangle)`

@MoonlightSentinel created dlang/dmd pull request #13895 "Fix 22489 - dtoh: Handle custom mangling for functions (and globals)" fixing this issue: - Fix 22489 - dtoh: Handle custom mangling for functions (and globals) Explicit mangling provided via `pragma(mangle, "..")` cannot be mapped to C++. For `extern(C)` function it's possible to emulate the behavior by replacing the identifier with the custom mangling. This doesn't work for `extern(C++)` functions, so they are ignored. The same rationale + solution applies to global variables with custom mangling. https://github.com/dlang/dmd/pull/13895

dlang/dmd pull request #13895 "Fix 22489 - dtoh: Handle custom mangling for functions (and globals)" was merged into master: - 0a2409ecb346f0fd3158c895574da755a8da3f1c by MoonlightSentinel: Fix 22489 - dtoh: Handle custom mangling for functions (and globals) Explicit mangling provided via `pragma(mangle, "..")` cannot be mapped to C++. For `extern(C)` function it's possible to emulate the behavior by replacing the identifier with the custom mangling. This doesn't work for `extern(C++)` functions, so they are ignored. The same rationale + solution applies to global variables with custom mangling. https://github.com/dlang/dmd/pull/13895