[clang] [clang-cl] Fix value of __FUNCTION__ in MSVC mode. (PR #67592)

[Aaron Ballman via cfe-commits]

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@@ -463,8 +470,73 @@ void ctor_tests() {
 constexpr SL global_sl = SL::current();
 static_assert(is_equal(global_sl.function(), ""));
 
+template <class T>
+class TestBI {
+public:
+   TestBI() {
+#ifdef MS
+      static_assert(is_equal(__FUNCTION__, "test_func::TestBI<int>::TestBI"));
+      static_assert(is_equal(__func__, "TestBI"));
+#else
+      static_assert(is_equal(__func__, "TestBI"));
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AaronBallman wrote:

I assume that for all of these, you intend to test `__FUNCTION__` and `__func__`, not `__func__` twice.

https://github.com/llvm/llvm-project/pull/67592