build: unify the warning policy across compilers (clang-cl: 124k warnings -> 2.7k, 21% faster) (#15328)

CMakeLists.txt

@@ -59,6 +59,13 @@ if (APPLE)
     message(STATUS "CMAKE_OSX_DEPLOYMENT_TARGET: ${CMAKE_OSX_DEPLOYMENT_TARGET}")
 endif ()
 
+# Keep MSVC's default /W3 out of CMAKE_<LANG>_FLAGS so it can be applied to our own
+# targets only. Silencing a bundled target would otherwise override a warning level,
+# which cl reports as D9025 for every file it compiles.
+if (POLICY CMP0092)
+    cmake_policy(SET CMP0092 NEW)
+endif ()
+
 project(OrcaSlicer)
 
 # Backward compatibility for old CMake versions
@@ -126,6 +133,8 @@ option(SLIC3R_GUI               "Compile OrcaSlicer with GUI components (OpenGL,
 option(SLIC3R_FHS               "Assume OrcaSlicer is to be installed in a FHS directory structure" 0)
 option(SLIC3R_PROFILE           "Compile OrcaSlicer with an invasive Shiny profiler" 0)
 option(SLIC3R_PCH               "Use precompiled headers" 1)
+option(SLIC3R_WARNINGS          "Emit compiler warnings for OrcaSlicer sources" 1)
+option(SLIC3R_BUNDLED_WARNINGS  "Emit compiler warnings for bundled third-party sources" 0)
 option(SLIC3R_MSVC_COMPILE_PARALLEL "Compile on Visual Studio in parallel" 1)
 option(SLIC3R_MSVC_PDB          "Generate PDB files on MSVC in Release mode" 1)
 option(SLIC3R_ASAN              "Enable ASan on Clang and GCC" 0)
@@ -335,14 +344,16 @@ if (MSVC AND CMAKE_CXX_COMPILER_ID STREQUAL Clang)
 
     # clang-cl can interpret SYSTEM header paths if -imsvc is used
     set(CMAKE_INCLUDE_SYSTEM_FLAG_CXX "-imsvc")
-
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall \
-        -Wno-old-style-cast -Wno-reserved-id-macro -Wno-c++98-compat-pedantic")
 else ()
     set(IS_CLANG_CL FALSE)
 endif ()
 
 if (MSVC)
+    # CMP0092 only applies when the cache is created; an existing tree keeps its /W3,
+    # which a silenced bundled target would then override (D9025, once per file).
+    string(REGEX REPLACE "/W[0-4]" "" CMAKE_C_FLAGS   "${CMAKE_C_FLAGS}")
+    string(REGEX REPLACE "/W[0-4]" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+
     # /MP only matters for the VS generators, where CMake turns it into the
     # MultiProcessorCompilation property. Ninja parallelises on its own, and
     # clang-cl warns "argument unused" if the flag reaches it.
@@ -526,8 +537,15 @@ if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUXX)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fext-numeric-literals" )
 endif()
 
-if (NOT MSVC AND ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang"))
-    if (NOT MINGW)
+if ((NOT MSVC OR IS_CLANG_CL) AND ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang"))
+    if (IS_CLANG_CL)
+        # clang-cl reads -Wall as MSVC /Wall, which clang maps to -Weverything. /W4 is
+        # its -Wall -Wextra and, unlike /clang:-Wall, is ordered with the -Wno-* below
+        # instead of after them. The -Wextra-only warnings are dropped again so the set
+        # matches what -Wall gives the GNU/Clang builds.
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4" )
+        add_compile_options(-Wno-unused-parameter -Wno-ignored-qualifiers -Wno-missing-field-initializers)
+    elseif (NOT MINGW)
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall" )
     endif ()
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-reorder" )
@@ -1089,8 +1107,57 @@ function(orcaslicer_copy_dlls target config postfix output_dlls)
 endfunction()
 
 
+# Bundled sources set their own warning flags, and a plain -Wall there means /Wall
+# (= -Weverything) under clang-cl. Target options are applied after the ones a target
+# set on itself, so these win. Targets are discovered rather than listed so a newly
+# bundled library needs no maintenance here.
+function(orcaslicer_silence_third_party_warnings _dir)
+    get_property(_subdirs DIRECTORY "${_dir}" PROPERTY SUBDIRECTORIES)
+    foreach (_subdir IN LISTS _subdirs)
+        orcaslicer_silence_third_party_warnings("${_subdir}")
+    endforeach ()
+    get_property(_targets DIRECTORY "${_dir}" PROPERTY BUILDSYSTEM_TARGETS)
+    foreach (_target IN LISTS _targets)
+        get_target_property(_type ${_target} TYPE)
+        if (NOT _type STREQUAL "INTERFACE_LIBRARY" AND NOT _type STREQUAL "UTILITY")
+            if (MSVC AND NOT IS_CLANG_CL)
+                # Drop any level the target set for itself, or -w overrides it and cl
+                # reports D9025 once per file.
+                get_target_property(_opts ${_target} COMPILE_OPTIONS)
+                if (_opts)
+                    string(REGEX REPLACE "/W[0-4]|/Wall" "" _opts "${_opts}")
+                    string(REGEX REPLACE ";;+" ";" _opts "${_opts}")
+                    set_target_properties(${_target} PROPERTIES COMPILE_OPTIONS "${_opts}")
+                endif ()
+                # CMake maps a level into the VS generator's WarningLevel element, while a
+                # bare -w stays on the command line and trips D9025 there, once per file.
+                target_compile_options(${_target} PRIVATE /W0)
+            else ()
+                target_compile_options(${_target} PRIVATE -w)
+            endif ()
+        endif ()
+    endforeach ()
+endfunction()
+
+
 # libslic3r, OrcaSlicer GUI and the OrcaSlicer executable.
 add_subdirectory(deps_src)
+
+if (NOT SLIC3R_BUNDLED_WARNINGS)
+    orcaslicer_silence_third_party_warnings("${CMAKE_CURRENT_SOURCE_DIR}/deps_src")
+endif ()
+
+# Warning level for the targets added below: our sources, plus glad and libvgcode,
+# which are vendored but live under src/. The deps_src libraries were configured just
+# above. CMP0092 left MSVC without a default level, so it is set here.
+if (NOT SLIC3R_WARNINGS)
+    add_compile_options(-w)
+elseif (MSVC AND NOT IS_CLANG_CL)
+    # /we4715 is C4715, no return from a non-void function, matching the
+    # -Werror=return-type the GNU/Clang builds apply.
+    add_compile_options(/W3 /we4715)
+endif ()
+
 add_subdirectory(src)
 set_property(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY VS_STARTUP_PROJECT OrcaSlicer_app_gui)
 
@@ -1102,6 +1169,10 @@ endif()
 
 if(BUILD_TESTS)
     add_subdirectory(tests)
+    if (NOT SLIC3R_BUNDLED_WARNINGS)
+        # Catch2 is vendored under tests/ and sets its own warning flags too.
+        orcaslicer_silence_third_party_warnings("${CMAKE_CURRENT_SOURCE_DIR}/tests/catch2")
+    endif ()
 endif()
 
 if (NOT WIN32 AND NOT APPLE)