[libxslt] cmake: Enable GCC compiler warnings

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 5d8d8dd892b5b5827e1e7ba915158e33f4dfe606
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Thu Sep 1 07:27:26 2022 +0200

    cmake: Enable GCC compiler warnings

 .gitlab-ci.yml | 4 ++--
 CMakeLists.txt | 7 +++++++
 2 files changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fe61164c..05d396ef 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -68,7 +68,7 @@ clang:msan:
     - export PATH=$CI_PROJECT_DIR/libxml2-install/bin:$PATH
     - export LD_LIBRARY_PATH=$CI_PROJECT_DIR/libxml2-install/bin:$LD_LIBRARY_PATH
   script:
-    - cmake -DBUILD_SHARED_LIBS=$BUILD_SHARED_LIBS -DCMAKE_INSTALL_PREFIX=libxslt-install 
-DCMAKE_BUILD_TYPE=RelWithDebInfo -S . -B libxslt-build
+    - cmake -DBUILD_SHARED_LIBS=$BUILD_SHARED_LIBS -DCMAKE_INSTALL_PREFIX=libxslt-install 
-DCMAKE_C_FLAGS='-Werror' -DCMAKE_BUILD_TYPE=RelWithDebInfo -S . -B libxslt-build
     - cmake --build libxslt-build --target install
     - mkdir -p libxslt-install/share/libxslt
     - cp Copyright libxslt-install/share/libxslt
@@ -143,7 +143,7 @@ cmake:linux:clang:static:
     - $Env:CMAKE_PREFIX_PATH="$Env:CI_PROJECT_DIR\libxml2-install;$Env:CMAKE_PREFIX_PATH"
     - $Env:Path="$Env:CI_PROJECT_DIR\libxml2-install\bin;$Env:Path"
   script:
-    - cmake -G Ninja -DBUILD_SHARED_LIBS="$Env:BUILD_SHARED_LIBS" -DCMAKE_INSTALL_PREFIX=libxslt-install 
-DCMAKE_BUILD_TYPE=RelWithDebInfo -S . -B libxslt-build
+    - cmake -G Ninja -DBUILD_SHARED_LIBS="$Env:BUILD_SHARED_LIBS" -DCMAKE_INSTALL_PREFIX=libxslt-install 
-DCMAKE_C_FLAGS='-Werror' -DCMAKE_BUILD_TYPE=RelWithDebInfo -S . -B libxslt-build
     - cmake --build libxslt-build --target install
     - New-Item -ItemType Directory libxslt-install\share\libxslt
     - Copy-Item Copyright libxslt-install\share\libxslt
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 01e5bd62..339b42c9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -77,6 +77,13 @@ set(LIBEXSLT_VERSION ${LIBEXSLT_DOTTED_VERSION})
 
 set(MODULE_EXTENSION "${CMAKE_SHARED_LIBRARY_SUFFIX}")
 
+if(CMAKE_C_COMPILER_ID MATCHES "Clang" OR CMAKE_C_COMPILER_ID STREQUAL "GNU")
+       set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wshadow \
+-Wpointer-arith -Wcast-align -Wwrite-strings -Waggregate-return \
+-Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline \
+-Wredundant-decls -Wno-long-long -Wno-format-extra-args")
+endif()
+
 if(LIBXSLT_WITH_CRYPTO AND NOT WIN32)
        list(APPEND CMAKE_REQUIRED_LIBRARIES Gcrypt::Gcrypt)
 endif()