[cmake] Enable Clang warnings about redundant semicolons

This matches what GCC warns about when -pedantic is enabled.

This should avoid such redundant semicolons creeping into the codebase.

Differential Revision: https://reviews.llvm.org/D98941

diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index d85fe13..c250a77 100644 (file)
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -668,6 +668,11 @@ if (LLVM_ENABLE_WARNINGS AND (LLVM_COMPILER_IS_GCC_COMPATIBLE OR CLANG_CL))
   if (LLVM_ENABLE_PEDANTIC AND LLVM_COMPILER_IS_GCC_COMPATIBLE)
     append("-pedantic" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     append("-Wno-long-long" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+
+    # GCC warns about redundant toplevel semicolons (enabled by -pedantic
+    # above), while Clang doesn't. Enable the corresponding Clang option to
+    # pick up on these even in builds with Clang.
+    add_flag_if_supported("-Wc++98-compat-extra-semi" CXX98_COMPAT_EXTRA_SEMI_FLAG)
   endif()
 
   add_flag_if_supported("-Wimplicit-fallthrough" IMPLICIT_FALLTHROUGH_FLAG)