CI/Build - Enable -Werror on GCC/Clang

[jijinbei]

Motivation

CI previously treated warnings differently across platforms — macOS had -Werror -Wall -Wextra injected from the workflow, while Linux and Windows did not. A warning that broke macOS CI often built fine on Linux (and vice versa), making it hard to keep all three green at once. This PR unifies warning handling in the shared CMake flag module so every GCC/Clang build — Linux, macOS, and the MSVC-ClangCL combination — enforces the same set.

Summary

• Enable -Werror on GCC/Clang in a shared CMake block; opt out -Warray-bounds, -Wmaybe-uninitialized, -Wstringop-overflow (GCC 15 false positives in inlined STL).
• Also enable -Wzero-as-null-pointer-constant as error.
• Remove now-redundant -Werror flags from the macOS CI action.

Fixes surfaced by the stricter build:

• 3 latent uninitialized reads.
• 4 sort/memcpy ranges clamped on fixed-size buffers.
• 8 zero-as-null-pointer sites (macros, X11 CopyFromParent/Aspect_Display sentinels, bundled FlexLexer.h).

Other stricter flags (-Wold-style-cast, -Wnon-virtual-dtor, etc.) were evaluated but dropped from this PR — the diffs were too large and are better suited to dedicated follow-ups.

Test plan

• Linux GCC / Linux Clang / macOS Clang / Windows MSVC — CI green.
• GTest pass.

CLA ID

1142

[dpasukhi]

CLA ID 1142

[Copilot]

Pull request overview

This PR aims to make warning handling consistent across GCC/Clang builds by enforcing warnings-as-errors in CI configuration, and it fixes multiple warning sites that become build-breaking under stricter flags.

Changes:

• Inject -Werror (plus select warning toggles) into the shared GitHub Action used for configuring Linux/macOS builds.
• Replace several 0 / CopyFromParent-style null constants with nullptr to satisfy -Wzero-as-null-pointer-constant.
• Add defensive bounds/clamps and initialization to avoid fixed-buffer overreads/memcpy/sort issues and uninitialized reads.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Visualization/TKV3d/SelectMgr/SelectMgr_BaseIntersector.cxx	Clamp sort range for fixed 4-element intersections buffer.
src/Visualization/TKService/Xw/Xw_Window.cxx	Avoid integer-as-pointer null constant when passing X11 Visual*.
src/Visualization/TKOpenGl/OpenGl/OpenGl_Window_1.mm	Use nullptr for rendering-context null checks.
src/Visualization/TKOpenGl/OpenGl/OpenGl_Context.hxx	Use nullptr for Aspect_Display null passing on Apple paths.
src/ModelingAlgorithms/TKMesh/BRepMesh/delabella.pxx	Replace default pointer args = 0 with = nullptr.
src/ModelingAlgorithms/TKGeomAlgo/ApproxInt/ApproxInt_MultiLine.gxx	Replace 0 with nullptr for a void* member init.
src/FoundationClasses/TKernel/NCollection/NCollection_LocalArray.hxx	Clamp inline move/copy operations to inline capacity.
src/FoundationClasses/TKernel/Message/Message_PrinterOStream.cxx	Initialize aCode to avoid uninitialized use.
src/FoundationClasses/TKernel/FlexLexer/FlexLexer.h	Replace default pointer args = 0 with = nullptr.
src/FoundationClasses/TKMath/Poly/Poly_MergeNodesTool.cxx	Clamp sort range to fixed Vec4 capacity.
src/FoundationClasses/TKMath/MathRoot/MathRoot_Trig.hxx	Clamp quartic root count to fixed storage capacity.
src/DataExchange/TKDEVRML/VrmlData/VrmlData_Node.hxx	Update macro to return nullptr instead of 0L.
src/DataExchange/TKDESTEP/StepData/StepData_EnumTool.cxx	Zero-init local buffer to avoid uninitialized reads.
src/DataExchange/TKDEIGES/IGESData/IGESData_IGESWriter.cxx	Clamp short-label copy to 8-char fixed buffer.
src/ApplicationFramework/TKTObj/TObj/TObj_Persistence.hxx	Replace (const TObj_Persistence*)0 with a nullptr cast.
.github/actions/configure-occt/action.yml	Add -Werror/warning toggles to macOS+Linux CMake configure invocation; remove redundant older macOS flags line.

Comments suppressed due to low confidence (1)

src/DataExchange/TKDESTEP/StepData/StepData_EnumTool.cxx:108

• StepData_EnumTool::AddDefinition() can still index text[n1 - 1] when n1 == 0 (e.g., if term ends with whitespace and the last token has already been flushed in the loop). With char text[80] = {0}; this becomes easier to hit deterministically and is undefined behavior. Consider guarding all text[n1 - 1] accesses with n1 > 0 (or restructuring the end-of-function handling so the final "append trailing '.'" logic only runs when a token is currently being built).

  char text[80] = {0};
  if (!term)
    return;
  if (term[0] == '\0')
    return;

[Copilot]

CMAKE_CXX_FLAGS here includes -Wno-unknown-warning-option, which is Clang-specific. Since this action supports inputs.compiler: gcc, invoking it with GCC would fail on an unknown option (and -Werror may make this worse). Consider making the warning-flag list conditional on the selected compiler (or moving compiler-specific flags into CMake logic that checks CMAKE_CXX_COMPILER_ID).

Suggested change

-D CMAKE_CXX_FLAGS="-Werror -Wzero-as-null-pointer-constant -Wno-unknown-warning-option -Wno-error=array-bounds -Wno-error=maybe-uninitialized -Wno-error=stringop-overflow -Wno-deprecated-declarations -Wno-error=cast-function-type-mismatch" \

-D CMAKE_CXX_FLAGS="${{ inputs.compiler == 'clang' && '-Werror -Wzero-as-null-pointer-constant -Wno-unknown-warning-option -Wno-error=array-bounds -Wno-error=maybe-uninitialized -Wno-error=stringop-overflow -Wno-deprecated-declarations -Wno-error=cast-function-type-mismatch' || '-Werror -Wzero-as-null-pointer-constant -Wno-error=array-bounds -Wno-error=maybe-uninitialized -Wno-error=stringop-overflow -Wno-deprecated-declarations -Wno-error=cast-function-type-mismatch' }}" \

[Copilot]

PR description says -Werror is enabled via a shared CMake flag module and removed from the macOS CI workflow, but this action still injects -Werror directly through CMAKE_CXX_FLAGS (and does so differently for macOS vs Linux). If the intent is to centralize this in CMake, consider removing these injected flags from the action and relying on the shared CMake flag module instead (or update the PR description to match the implementation).

[Copilot]

Same as macOS: the Linux CMAKE_CXX_FLAGS includes -Wno-unknown-warning-option and Clang/GCC-specific -Wno-error=... suppressions in one string. If this action is ever run with GCC, the Clang-only flag will fail; if run with Clang, the GCC-only -Wno-error=array-bounds/etc. relies on -Wno-unknown-warning-option to silence unknown-warning diagnostics. Consider splitting the flag sets by compiler to avoid relying on cross-compiler suppression flags.

Suggested change

	cmake -G "Unix Makefiles" \
	-D CMAKE_C_COMPILER=${{ inputs.compiler == 'clang' && 'clang' || 'gcc' }} \
	-D CMAKE_CXX_COMPILER=${{ inputs.compiler == 'clang' && 'clang++' || 'g++' }} \
	-D CMAKE_CXX_FLAGS="-Werror -Wzero-as-null-pointer-constant -Wno-unknown-warning-option -Wno-error=array-bounds -Wno-error=maybe-uninitialized -Wno-error=stringop-overflow" \
	CMAKE_CXX_FLAGS="-Werror -Wzero-as-null-pointer-constant"
	if [ "${{ inputs.compiler }}" = "clang" ]; then
	CMAKE_CXX_FLAGS="$CMAKE_CXX_FLAGS -Wno-unknown-warning-option"
	else
	CMAKE_CXX_FLAGS="$CMAKE_CXX_FLAGS -Wno-error=array-bounds -Wno-error=maybe-uninitialized -Wno-error=stringop-overflow"
	fi
	cmake -G "Unix Makefiles" \
	-D CMAKE_C_COMPILER=${{ inputs.compiler == 'clang' && 'clang' || 'gcc' }} \
	-D CMAKE_CXX_COMPILER=${{ inputs.compiler == 'clang' && 'clang++' || 'g++' }} \
	-D CMAKE_CXX_FLAGS="$CMAKE_CXX_FLAGS" \

[jijinbei]

thanks!!