[clang] [CIR] Disable gcc partially overloaded virtual warning (PR #130322)

[Andy Kaylor via cfe-commits]

https://github.com/andykaylor created https://github.com/llvm/llvm-project/pull/130322

GCC, unlike clang, issues a warning when one virtual function is overridden in a derived class but one or more other virtual functions with the same name and different signature from a base class are not overridden. This leads to many warnings in the MLIR and ClangIR code when using the OpenConversionPattern<>::matchAndRewrite() function in the ordinary way. The "hiding" behavior is what we want, so we're just disabling the warning here.

>From 283631c92bdbf8d73cedf97cf714fe47a32d750e Mon Sep 17 00:00:00 2001
From: Andy Kaylor <akaylor at nvidia.com>
Date: Fri, 7 Mar 2025 10:37:42 -0800
Subject: [PATCH] [CIR] Disable gcc partially overloaded virtual warning

GCC, unlike clang, issues a warning when one virtual function is overridden
in a derived class but one or more other virtual functions with the same
name and different signature from a base class are not overridden. This
leads to many warnings in the MLIR and ClangIR code when using the
OpenConversionPattern<>::matchAndRewrite() function in the ordinary way.
The "hiding" behavior is what we want, so we're just disabling the warning
here.
---
 clang/lib/CIR/CMakeLists.txt       | 11 +++++++++++
 clang/tools/cir-opt/CMakeLists.txt | 11 +++++++++++
 2 files changed, 22 insertions(+)

diff --git a/clang/lib/CIR/CMakeLists.txt b/clang/lib/CIR/CMakeLists.txt
index 4a99ecb33dfb2..7bdf3fcc59035 100644
--- a/clang/lib/CIR/CMakeLists.txt
+++ b/clang/lib/CIR/CMakeLists.txt
@@ -1,6 +1,17 @@
 include_directories(${LLVM_MAIN_SRC_DIR}/../mlir/include)
 include_directories(${CMAKE_BINARY_DIR}/tools/mlir/include)
 
+# GCC, unlike clang, issues a warning when one virtual function is overridden
+# in a derived class but one or more other virtual functions with the same
+# name and different signature from a base class are not overridden. This
+# leads to many warnings in the MLIR and ClangIR code when using the
+# OpenConversionPattern<>::matchAndRewrite() function in the ordinary way.
+# The "hiding" behavior is what we want, so we're just disabling the warning
+# here.
+if (LLVM_COMPILER_IS_GCC_COMPATIBLE AND (NOT "${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang"))
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-overloaded-virtual")
+endif()
+
 add_subdirectory(Dialect)
 add_subdirectory(CodeGen)
 add_subdirectory(FrontendAction)
diff --git a/clang/tools/cir-opt/CMakeLists.txt b/clang/tools/cir-opt/CMakeLists.txt
index 75bec5f4e1b0b..ca7ee44f6fd75 100644
--- a/clang/tools/cir-opt/CMakeLists.txt
+++ b/clang/tools/cir-opt/CMakeLists.txt
@@ -4,6 +4,17 @@ get_property(conversion_libs GLOBAL PROPERTY MLIR_CONVERSION_LIBS)
 include_directories(${LLVM_MAIN_SRC_DIR}/../mlir/include)
 include_directories(${CMAKE_BINARY_DIR}/tools/mlir/include)
 
+# GCC, unlike clang, issues a warning when one virtual function is overridden
+# in a derived class but one or more other virtual functions with the same
+# name and different signature from a base class are not overridden. This
+# leads to many warnings in the MLIR and ClangIR code when using the
+# OpenConversionPattern<>::matchAndRewrite() function in the ordinary way.
+# The "hiding" behavior is what we want, so we're just disabling the warning
+# here.
+if (LLVM_COMPILER_IS_GCC_COMPATIBLE AND (NOT "${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang"))
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-overloaded-virtual")
+endif()
+
 add_clang_tool(cir-opt
   cir-opt.cpp
 )