mstorsjo added a comment.
FWIW, I had debugged the issue described here and posted about it on Discord,
but never got around to posting it here. I think the MSVC build error above
gets fixed by this patch:
diff --git a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
index f14e2732f6eb..788072cffd87 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Lua/Lua.cpp
@@ -24,6 +24,7 @@ using namespace lldb;
#if _MSC_VER
#pragma warning (push)
#pragma warning (disable : 4190)
+llvm::Expected<bool> unusedFuncForInstantiatingExpectedBool() { return true;
}
#endif
extern "C" llvm::Expected<bool> LLDBSwigLuaBreakpointCallbackFunction(
Here's a minimal showcase of the root issue:
$ cat cpp-ret-c.cpp
template<class T> class MyClass {
public:
T a;
};
extern "C" MyClass<int> unmangledFunction();
$ cl -c cpp-ret-c.cpp
cpp-ret-c.cpp
cpp-ret-c.cpp(5): error C2526: 'unmangledFunction': C linkage function cannot
return C++ class 'MyClass<int>'
cpp-ret-c.cpp(5): note: see declaration of 'MyClass<int>'
$ cat cpp-ret-c2.cpp
template<class T> class MyClass {
public:
T a;
};
MyClass<int> unusedFunc() { return MyClass<int>{0}; }
extern "C" MyClass<int> unmangledFunction();
$ cl -c cpp-ret-c2.cpp
cpp-ret-c2.cpp
So this construct, in MSVC, requires that the problematic return type template
already has been instantiated somewhere else first. The case in the python
plugin works, but it has been copied to the Lua plugin too, where it fails.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91508/new/
https://reviews.llvm.org/D91508
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