fix #4405

Author: Cyan4973

.github/workflows/cmake-tests.yml

@@ -44,6 +44,7 @@ jobs:
     name: "CMake Cross-Platform (Spaces in Path)"
     runs-on: ${{ matrix.os }}
     strategy:
+      fail-fast: false
       matrix:
         include:
           - os: ubuntu-latest
@@ -77,6 +78,7 @@ jobs:
     name: "CMake Windows VS2022 (${{ matrix.name }})"
     runs-on: ${{ matrix.runner }}
     strategy:
+      fail-fast: false
       matrix:
         include:
           - generator: "Visual Studio 17 2022"

build/cmake/CMakeModules/AddZstdCompilationFlags.cmake

@@ -22,9 +22,13 @@ function(EnableCompilerFlag _flag _C _CXX _LD)
         endif ()
     endif ()
     if (_CXX)
-        CHECK_CXX_COMPILER_FLAG(${_flag} CXX_FLAG_${varname})
-        if (CXX_FLAG_${varname})
-            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_flag}" PARENT_SCOPE)
+        # Only check CXX flags if CXX language is enabled
+        get_property(languages GLOBAL PROPERTY ENABLED_LANGUAGES)
+        if("CXX" IN_LIST languages)
+            CHECK_CXX_COMPILER_FLAG(${_flag} CXX_FLAG_${varname})
+            if (CXX_FLAG_${varname})
+                set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_flag}" PARENT_SCOPE)
+            endif ()
         endif ()
     endif ()
     if (_LD)
@@ -54,19 +58,24 @@ macro(ADD_ZSTD_COMPILATION_FLAGS _C _CXX _LD)
     # compiler flags to mark the stack as non-executable.
     set(ZSTD_HAS_NOEXECSTACK false)
 
-    if (CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang" OR MINGW) #Not only UNIX but also WIN32 for MinGW
+    # Detect clang-cl: it identifies as Clang but should be treated as MSVC
+    # Use C compiler info since CXX might not be enabled yet
+    set(CLANG_CL_DETECTED FALSE)
+    if(CMAKE_C_COMPILER_ID MATCHES "Clang" AND (MSVC OR CMAKE_C_SIMULATE_ID STREQUAL "MSVC"))
+        set(CLANG_CL_DETECTED TRUE)
+        message(STATUS "Detected clang-cl compiler - using MSVC-compatible flags")
+    endif()
+
+    # Handle GNU/Clang compilers (but not clang-cl which is handled in MSVC section)
+    # Use C compiler ID since CXX might not be enabled yet
+    if ((CMAKE_C_COMPILER_ID MATCHES "GNU|Clang" OR MINGW) AND NOT CLANG_CL_DETECTED)
         # It's possible to select the exact standard used for compilation.
         # It's not necessary, but can be employed for specific purposes.
         # Note that zstd source code is compatible with both C++98 and above
         # and C-gnu90 (c90 + long long + variadic macros ) and above
         # EnableCompilerFlag("-std=c++11" false true) # Set C++ compilation to c++11 standard
         # EnableCompilerFlag("-std=c99" true false)   # Set C compilation to c99 standard
-        if (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND MSVC)
-            # clang-cl normally maps -Wall to -Weverything.
-            EnableCompilerFlag("/clang:-Wall" _C _CXX false)
-        else ()
-            EnableCompilerFlag("-Wall" _C _CXX false)
-        endif ()
+        EnableCompilerFlag("-Wall" _C _CXX false)
         EnableCompilerFlag("-Wextra" _C _CXX false)
         EnableCompilerFlag("-Wundef" _C _CXX false)
         EnableCompilerFlag("-Wshadow" _C _CXX false)
@@ -95,16 +104,26 @@ macro(ADD_ZSTD_COMPILATION_FLAGS _C _CXX _LD)
                 endif()
             endif()
         endif()
-    elseif (MSVC) # Add specific compilation flags for Windows Visual
+    endif()
+    
+    if (MSVC OR CLANG_CL_DETECTED) # Add specific compilation flags for Windows Visual (including clang-cl)
 
         set(ACTIVATE_MULTITHREADED_COMPILATION "ON" CACHE BOOL "activate multi-threaded compilation (/MP flag)")
         if (CMAKE_GENERATOR MATCHES "Visual Studio" AND ACTIVATE_MULTITHREADED_COMPILATION)
             EnableCompilerFlag("/MP" _C _CXX false)
         endif ()
 
-        # UNICODE SUPPORT
-        EnableCompilerFlag("/D_UNICODE" _C _CXX false)
-        EnableCompilerFlag("/DUNICODE" _C _CXX false)
+        # For clang-cl, use clang-specific warning flags with MSVC syntax
+        if (CLANG_CL_DETECTED)
+            EnableCompilerFlag("/clang:-Wall" _C _CXX false)
+            EnableCompilerFlag("/clang:-Wextra" _C _CXX false)
+            # Don't set UNICODE flags for clang-cl as they cause RC issues
+        else()
+            # UNICODE SUPPORT (only for regular MSVC, not clang-cl)
+            EnableCompilerFlag("/D_UNICODE" _C _CXX false)
+            EnableCompilerFlag("/DUNICODE" _C _CXX false)
+        endif()
+        
         # Enable asserts in Debug mode
         if (CMAKE_BUILD_TYPE MATCHES "Debug")
             EnableCompilerFlag("/DDEBUGLEVEL=1" _C _CXX false)

build/cmake/CMakeModules/ZstdOptions.cmake

@@ -58,8 +58,15 @@ if(MSVC)
     option(ZSTD_USE_STATIC_RUNTIME "Link to static runtime libraries" OFF)
 endif()
 
-# C++ support (needed for tests)
-set(ZSTD_ENABLE_CXX ${ZSTD_BUILD_TESTS})
+# C++ support (needed for tests and required for MSVC builds)
+if(MSVC)
+    # MSVC builds require CXX language support for proper project generation
+    set(ZSTD_ENABLE_CXX ON)
+else()
+    # For other compilers, only enable CXX when tests are built
+    set(ZSTD_ENABLE_CXX ${ZSTD_BUILD_TESTS})
+endif()
+
 if(ZSTD_ENABLE_CXX)
     enable_language(CXX)
 endif()

build/cmake/lib/CMakeLists.txt

@@ -100,6 +100,13 @@ endif ()
 if (MSVC)
     set(MSVC_RESOURCE_DIR ${ZSTD_SOURCE_DIR}/build/VS2010/libzstd-dll)
     set(PlatformDependResources ${MSVC_RESOURCE_DIR}/libzstd-dll.rc)
+    # Set specific properties for RC files only on Windows to avoid C/C++ flag contamination
+    if(WIN32)
+        set_source_files_properties(${PlatformDependResources} PROPERTIES
+            LANGUAGE RC
+            COMPILE_DEFINITIONS ""  # Clear any inherited definitions
+            COMPILE_FLAGS "/I \"${LIBRARY_DIR}\" /D_WIN32 /DWIN32")
+    endif()
 endif ()
 
 # Explicitly set the language to C for all files, including ASM files.
@@ -118,7 +125,6 @@ endmacro ()
 
 # Define directories containing the library's public headers
 set(PUBLIC_INCLUDE_DIRS ${LIBRARY_DIR})
-set(CMAKE_RC_FLAGS "${CMAKE_RC_FLAGS} /I \"${LIBRARY_DIR}\"")
 # Split project to static and shared libraries build
 set(library_targets)
 if (ZSTD_BUILD_SHARED)