[llvm] [NFC] [CMake] Add -Wno-dangling-else for GCC built unittests (PR #112817)

[James Henderson via llvm-commits]

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@@ -14,6 +14,20 @@ function(add_llvm_target_unittest test_dir_name)
   add_llvm_unittest(${test_dir_name} DISABLE_LLVM_LINK_LLVM_DYLIB ${ARGN})
 endfunction()
 
+# gtest macros like EXPECT_TRUE are expanded to a single line
+# multi-statement code with if/else. eg:
+#   if (...)
+#     EXPECT_TURE(...)
+# will be expanded into something like:
+#   if(...)
+#     switch (0) case 0: default: if (...) ; else return;;
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jh7370 wrote:

`EXPECT_TURE` -> `EXPECT_TRUE`
`if(...)` -> `if (...)`

https://github.com/llvm/llvm-project/pull/112817