fix: Mesh Boolean crash on Windows builds made with clang-cl (#16651)

Build without precompiled headers when the compiler is clang-cl, in both the slicer and the wxWidgets dependency, and add a CI check that fails if broken exception throw info comes back.

With a precompiled header, clang-cl can leave the copy constructor out of the throw info it emits for an exception type (llvm/llvm-project#53486, open since 2022 and still present in clang 22.1.3). The linker keeps one throw info per type for the whole binary. When it keeps one from a precompiled header file, a copy of that exception is bitwise, and the copy and the original free the same data.

Mesh Boolean hits this on every operation. mcut destroys a std::promise that was never set, which stores a broken_promise future_error in an exception_ptr. Freeing it corrupts the heap, and Windows ends the process with 0xC0000374. The 2.5.0-alpha release has broken throw info for 64 exception classes, including std::runtime_error, std::bad_alloc and boost exceptions.

scripts/check_exception_throw_info.ps1 runs after the Windows clang build and its uploads, before any deploy. It fails when an exception class has throw info both with and without a copy constructor, when OrcaSlicer.pdb is missing, or when it finds no exception classes at all. scripts/test_check_exception_throw_info.ps1 tests it on canned dumps.

build_win.bat now treats -l as --no-pch. The Windows ccache key drops the cl.exe version, which only mattered for precompiled headers.

The bug came in with #15428, which moved Windows CI to clang-cl. 2.4.2 was built with MSVC.

Fixes #16581

.github/workflows/build_all.yml

@@ -19,6 +19,8 @@ on:
      - 'build_linux.sh'
      - 'build_win.bat'
      - 'scripts/test_build_win.ps1'
+     - 'scripts/check_exception_throw_info.ps1'
+     - 'scripts/test_check_exception_throw_info.ps1'
      - 'build_release_macos.sh'
      - 'scripts/build_preset_cache.*'
      - 'scripts/flatpak/**'
@@ -41,6 +43,8 @@ on:
      - 'build_linux.sh'
      - 'build_win.bat'
      - 'scripts/test_build_win.ps1'
+     - 'scripts/check_exception_throw_info.ps1'
+     - 'scripts/test_check_exception_throw_info.ps1'
      - 'build_release_macos.sh'
      - 'scripts/build_preset_cache.*'
      - 'scripts/flatpak/**'
@@ -84,6 +88,10 @@ jobs:
         shell: powershell
         run: .\scripts\test_build_win.ps1
 
+      - name: Run the exception throw info check tests
+        shell: powershell
+        run: .\scripts\test_check_exception_throw_info.ps1
+
   build_linux:
     strategy:
       fail-fast: false

.github/workflows/build_orca.yml

@@ -65,15 +65,6 @@ jobs:
         shell: bash
         run: |
           leg="${{ runner.os }}-${{ inputs.arch || 'amd64' }}${{ runner.os == 'Windows' && format('-{0}', inputs.compiler) || '' }}"
-          # clang-cl refuses a precompiled header from another cl.exe build and ccache
-          # does not hash that build, so each one gets its own cache. The build number
-          # is read from cl.exe itself; the toolset directory keeps its name across patches.
-          if [ "${{ runner.os }}" = Windows ]; then
-            vswhere='/c/Program Files (x86)/Microsoft Visual Studio/Installer/vswhere.exe'
-            toolset=$(tr -d '\r\n' < "$("$vswhere" -latest -products '*' -find 'VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt' | tr -d '\r')")
-            cl=$("$vswhere" -latest -products '*' -find 'VC\Tools\MSVC\'"$toolset"'\**\cl.exe' | tr -d '\r' | head -1)
-            leg="$leg-vc$("$cl" 2>&1 | grep -o -E 'Version [0-9.]+' | cut -d' ' -f2)"
-          fi
           echo "CCACHE_LEG=$leg" >> "$GITHUB_ENV"
           echo "CCACHE_ENTRY=ccache-$leg-${{ github.run_id }}-${{ github.run_attempt }}" >> "$GITHUB_ENV"
 
@@ -552,6 +543,13 @@ jobs:
           name: OrcaSlicer_profile_validator_Windows_${{ env.ver }}
           path: ${{ github.workspace }}/build/src/Release/OrcaSlicer_profile_validator.exe
 
+      - name: Check exception throw info Win
+        if: runner.os == 'Windows' && inputs.compiler == 'clang'
+        working-directory: ${{ github.workspace }}
+        # After the uploads, so a failure still leaves the build and its PDB to inspect, and before any deploy.
+        shell: pwsh
+        run: scripts\check_exception_throw_info.ps1 -BuildDir $env:BUILD_DIR
+
       - name: Deploy Windows release portable
         if: github.repository == 'OrcaSlicer/OrcaSlicer' && github.ref == 'refs/heads/main' && runner.os == 'Windows' && !vars.SELF_HOSTED
         uses: ./.github/actions/deploy-nightly

CMakeLists.txt

@@ -321,6 +321,14 @@ if (IS_CROSS_COMPILE)
     set(BUILD_TESTS OFF CACHE BOOL "" FORCE)
 endif ()
 
+# With a precompiled header, clang-cl can omit an exception type's copy constructor from its throw info,
+# so copies of the exception share and double-free their data: https://github.com/llvm/llvm-project/issues/53486
+if (MSVC AND CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    message(STATUS "clang-cl: building without the precompiled header (llvm/llvm-project#53486)")
+    set_property(CACHE SLIC3R_PCH PROPERTY HELPSTRING "Use precompiled headers (ignored with clang-cl, llvm/llvm-project#53486)")
+    set(SLIC3R_PCH OFF)
+endif ()
+
 # Print out the SLIC3R_* cache options
 get_cmake_property(_cache_vars CACHE_VARIABLES)
 list (SORT _cache_vars)

build_win.bat

@@ -53,7 +53,7 @@ call :add_section "Build configuration"
 call :add_arg config string "" config "release, debug, relwithdebinfo or minsizerel (default: release)"
 call :add_arg target_arch string "" arch "x64 or arm64 (default: the host architecture)"
 call :add_arg slicer_asan bool a asan "Build the slicer with ASAN enabled"
-call :add_arg no_pch bool "" no-pch "Build without the precompiled header, implied by --cache"
+call :add_arg no_pch bool "" no-pch "Build without the precompiled header, implied by -l and --cache"
 
 call :add_section "Toolchain"
 call :add_arg use_clang_cl bool l clang-cl "Use clang-cl as the compiler"
@@ -388,6 +388,9 @@ if "%use_ninja%" == "ON" if "%use_msbuild%" == "ON" (
     exit /b 1
 )
 
+REM CMakeLists turns the precompiled header off for clang-cl (llvm/llvm-project#53486).
+if "%use_clang_cl%" == "ON" set "no_pch=ON"
+
 set "generator=!vs_gen_%vs_version%!"
 if "%use_ninja%" == "ON" (
     set "generator=Ninja Multi-Config"
@@ -543,7 +546,7 @@ REM real path rather than one glued onto the repository root.
 for %%p in ("!build_dir!") do set "build_full=%%~fp"
 echo Configuration: %build_type%, %arch%
 if not "%clang_exe%" == "" echo Compiler: %clang_exe%
-if "%no_pch%" == "ON" echo Precompiled header: off
+if "%build_slicer%" == "ON" if "%no_pch%" == "ON" echo Precompiled header: off
 if not "%cache_args%" == "" echo Compiler cache: %cache_exe%
 
 set "SIG_FLAG="
@@ -716,8 +719,8 @@ if "%build_slicer%" == "ON" (
         set "slicer_args=!slicer_args! -DSLIC3R_ASAN=ON"
     )
 
-    REM A later -DSLIC3R_PCH=ON in ORCA_SLICER_CMAKE_ARGS still wins, because
-    REM CMake takes the last definition on the command line.
+    REM Under cl, a later -DSLIC3R_PCH=ON in ORCA_SLICER_CMAKE_ARGS still wins,
+    REM because CMake takes the last definition on the command line.
     if "%no_pch%" == "ON" (
         set "slicer_args=!slicer_args! -DSLIC3R_PCH=OFF"
     )

deps/wxWidgets/wxWidgets.cmake

@@ -21,6 +21,14 @@ else ()
     set(_wx_edge "-DwxUSE_WEBVIEW_EDGE=OFF")
 endif ()
 
+# With a precompiled header, clang-cl can omit an exception type's copy constructor from its throw info,
+# so copies of the exception share and double-free their data: https://github.com/llvm/llvm-project/issues/53486
+if (MSVC AND CMAKE_C_COMPILER_ID STREQUAL "Clang")
+    set(_wx_precomp OFF)
+else ()
+    set(_wx_precomp ON)
+endif ()
+
 set(_wx_patch_command "")
 if (APPLE)
     set(_wx_patch_command
@@ -39,7 +47,7 @@ orcaslicer_add_cmake_project(
     PATCH_COMMAND ${_wx_patch_command}
     DEPENDS ${PNG_PKG} ${ZLIB_PKG} ${EXPAT_PKG} ${JPEG_PKG}
     CMAKE_ARGS
-        -DwxBUILD_PRECOMP=ON
+        -DwxBUILD_PRECOMP=${_wx_precomp}
         ${_wx_toolkit}
         "-DCMAKE_DEBUG_POSTFIX:STRING=${_wx_debug_postfix}"
         -DwxBUILD_DEBUG_LEVEL=0

scripts/check_exception_throw_info.ps1

@@ -0,0 +1,126 @@
+<#
+.SYNOPSIS
+    Fails when a Windows build has an exception class with broken throw info.
+
+.DESCRIPTION
+    Clang on the MSVC ABI can leave the copy constructor out of the CatchableType it emits for
+    an exception class that comes through a precompiled header
+    (https://github.com/llvm/llvm-project/issues/53486). The linker keeps one throw info per
+    class, so when it keeps such a record, a copy of that exception (std::exception_ptr, a catch
+    by value) shares its data with the original and the data is freed twice.
+
+    A class is either trivially copyable or not, so a binary should never have both a CatchableType
+    without a copy constructor (_CT??_R0?AV<class>@@@8<size>) and one with it
+    (_CT??_R0?AV<class>@@@8??0<class>...). The script lists each PDB's public symbols with the
+    llvm-pdbutil next to the build's compiler and reports every class that has both.
+
+    scripts\test_check_exception_throw_info.ps1 tests it.
+
+.PARAMETER BuildDir
+    The slicer build directory. Its CMakeCache.txt names the compiler, and its src\<Config>
+    holds the PDBs to check, which must include OrcaSlicer.pdb.
+
+.PARAMETER Config
+    The configuration whose PDBs to check (default: Release).
+
+.PARAMETER Pdb
+    PDBs to check instead of the ones in <BuildDir>\src\<Config>, as a list or comma-separated.
+
+.PARAMETER Dump
+    Saved `llvm-pdbutil dump --publics` output to check instead of PDBs. Needs no build.
+
+.EXAMPLE
+    scripts\check_exception_throw_info.ps1 -BuildDir build
+#>
+param(
+    [string] $BuildDir,
+    [string] $Config = 'Release',
+    [string[]] $Pdb,
+    [string[]] $Dump
+)
+$ErrorActionPreference = 'Stop'
+
+# powershell -File passes "a.pdb,b.pdb" as one string. A path that exists as given stays whole.
+function Split-PathList([string[]] $values) {
+    @($values | Where-Object { $_ } | ForEach-Object {
+        if ((Test-Path -LiteralPath $_) -or $_ -notmatch ',') { $_ } else { $_ -split ',' | Where-Object { $_ } }
+    })
+}
+
+$Dump = Split-PathList $Dump
+if (-not $Dump) {
+    if (-not $BuildDir) {
+        throw 'Name the slicer build directory with -BuildDir.'
+    }
+    $cache = Join-Path $BuildDir 'CMakeCache.txt'
+    if (-not (Test-Path $cache)) {
+        throw "No CMakeCache.txt in $BuildDir. Name the slicer build directory."
+    }
+    $entry = Select-String -Path $cache -Pattern '^CMAKE_CXX_COMPILER:\w+=(.+)$' | Select-Object -First 1
+    if (-not $entry) {
+        throw "No CMAKE_CXX_COMPILER in $cache."
+    }
+    $compiler = $entry.Matches[0].Groups[1].Value
+    # A tree configured with a bare compiler name found it on PATH.
+    if (-not (Split-Path $compiler)) {
+        $found = Get-Command $compiler -CommandType Application -ErrorAction SilentlyContinue | Select-Object -First 1
+        if (-not $found) {
+            throw "$compiler, the compiler in $cache, is not on PATH."
+        }
+        $compiler = $found.Source
+    }
+    $pdbutil = Join-Path (Split-Path $compiler) 'llvm-pdbutil.exe'
+    if (-not (Test-Path $pdbutil)) {
+        throw "No llvm-pdbutil.exe next to $compiler. This check needs a build made with Clang."
+    }
+
+    $Pdb = Split-PathList $Pdb
+    if (-not $Pdb) {
+        # OrcaSlicer.dll holds the slicer itself, so a check without it proves nothing.
+        $pdbDir = Join-Path $BuildDir "src\$Config"
+        if (-not (Test-Path (Join-Path $pdbDir 'OrcaSlicer.pdb'))) {
+            throw "No OrcaSlicer.pdb in $pdbDir."
+        }
+        $Pdb = @(Get-ChildItem $pdbDir -Filter *.pdb | ForEach-Object FullName)
+    }
+}
+
+$catchable = [regex]'`_CT\?\?_R0\?A[UV](.+?)@@@8([^`]*)`'
+$tmp = [IO.Path]::GetTempFileName()
+$failed = $false
+$classes = 0
+try {
+    foreach ($file in $(if ($Dump) { $Dump } else { $Pdb })) {
+        $text = $file
+        if (-not $Dump) {
+            $run = Start-Process -FilePath $pdbutil -ArgumentList 'dump', '--publics', "`"$file`"" -NoNewWindow -Wait -PassThru -RedirectStandardOutput $tmp
+            if ($run.ExitCode -ne 0) {
+                throw "llvm-pdbutil failed on $file."
+            }
+            $text = $tmp
+        }
+
+        $kinds = @{}
+        foreach ($match in $catchable.Matches([IO.File]::ReadAllText((Resolve-Path -LiteralPath $text).Path))) {
+            $class = $match.Groups[1].Value
+            if (-not $kinds.ContainsKey($class)) { $kinds[$class] = @{} }
+            $kinds[$class][$(if ($match.Groups[2].Value.StartsWith('??0')) { 'copy' } else { 'bitwise' })] = $true
+        }
+
+        $broken = @($kinds.Keys | Where-Object { $kinds[$_].Count -eq 2 } | Sort-Object)
+        "$(Split-Path -Leaf $file): $($kinds.Count) exception classes, $($broken.Count) with broken throw info"
+        foreach ($class in $broken) { "    $class" }
+        if ($broken.Count -gt 0) { $failed = $true }
+        $classes += $kinds.Count
+    }
+} finally {
+    Remove-Item $tmp -ErrorAction SilentlyContinue
+}
+
+# The slicer's PDBs always contain exception throw info, so finding none means the dump format or the PDBs changed.
+if ($classes -eq 0) {
+    'No exception classes found. Check that llvm-pdbutil still prints public symbols in backticks.'
+    $failed = $true
+}
+
+exit [int]$failed

scripts/test_build_win.ps1

@@ -301,6 +301,10 @@ $cases = @(
        Contains = @('Precompiled header: off') }
     @{ Name = 'the precompiled header is on unless asked'; Args = @('-s')
        NotContains = @('SLIC3R_PCH') }
+    @{ Name = '-l turns the precompiled header off'; Args = @('-s', '-l')
+       Contains = @('-DSLIC3R_PCH=OFF', 'Precompiled header: off') }
+    @{ Name = 'a deps-only build says nothing about the precompiled header'; Args = @('-d', '-l')
+       NotContains = @('Precompiled header') }
     @{ Name = '--no-pch works without a cache'; Args = @('-s', '--no-pch')
        NotContains = @('COMPILER_LAUNCHER') }
     @{ Name = 'the slicer build runs gettext'; Args = @('-s')

scripts/test_check_exception_throw_info.ps1

@@ -0,0 +1,93 @@
+<#
+.SYNOPSIS
+    Tests scripts/check_exception_throw_info.ps1 on canned llvm-pdbutil dumps.
+
+.DESCRIPTION
+    Each case runs the check in its own powershell -File process, as CI does, and asserts on the
+    exit code and output. Dumps are written to a temporary folder, so no build is needed.
+
+.EXAMPLE
+    powershell -File scripts/test_check_exception_throw_info.ps1
+#>
+$ErrorActionPreference = 'Stop'
+
+$check = Join-Path $PSScriptRoot 'check_exception_throw_info.ps1'
+$work = Join-Path ([IO.Path]::GetTempPath()) 'check_exception_throw_info_tests'
+Remove-Item -Recurse -Force $work -ErrorAction SilentlyContinue
+New-Item -ItemType Directory -Force -Path $work | Out-Null
+
+function Write-Dump([string] $path, [string[]] $symbols) {
+    New-Item -ItemType Directory -Force -Path (Split-Path $path) | Out-Null
+    $i = 0
+    $lines = @('                       Public Symbols', '============================================================')
+    foreach ($symbol in $symbols) {
+        $i++
+        $lines += "  $i | S_PUB32 [size = 48] ``$symbol``", '           flags = none, addr = 0007:0000'
+    }
+    Set-Content -Path $path -Encoding ascii -Value $lines
+}
+
+$bitwise = '_CT??_R0?AVfuture_error@std@@@840'
+$copy = '_CT??_R0?AVfuture_error@std@@@8??0future_error@std@@QEAA@AEBV01@@Z40'
+$trivial = '_CT??_R0?AUtag@@@81'
+Write-Dump "$work\broken.txt" @($bitwise, $copy, $trivial)
+Write-Dump "$work\clean.txt" @($copy, $trivial)
+Write-Dump "$work\empty.txt" @()
+Write-Dump "$work\a dir, with a comma\clean.txt" @($copy)
+
+# A build directory whose compiler has an llvm-pdbutil beside it but no OrcaSlicer.pdb.
+# Nothing runs the stand-in; the check stops before it gets there.
+$build = "$work\build"
+New-Item -ItemType Directory -Force -Path "$build\bin", "$build\src\Release" | Out-Null
+Copy-Item "$env:SystemRoot\System32\where.exe" "$build\bin\llvm-pdbutil.exe"
+Set-Content -Path "$build\CMakeCache.txt" -Encoding ascii -Value "CMAKE_CXX_COMPILER:FILEPATH=$build\bin\clang-cl.exe"
+Set-Content -Path "$build\src\Release\orca-slicer.pdb" -Value ''
+$bare = "$work\bare"
+New-Item -ItemType Directory -Force -Path $bare | Out-Null
+Set-Content -Path "$bare\CMakeCache.txt" -Encoding ascii -Value 'CMAKE_CXX_COMPILER:STRING=no-such-clang-cl.exe'
+
+$cases = @(
+    @{ Name = 'a class with and without a copy constructor fails'; Args = @('-Dump', "$work\broken.txt")
+       Exit = 1; Contains = @('1 with broken throw info', 'future_error@std') }
+    @{ Name = 'copy constructors and trivially copyable classes pass'; Args = @('-Dump', "$work\clean.txt")
+       Exit = 0; Contains = @('2 exception classes, 0 with broken throw info') }
+    @{ Name = 'no exception classes at all fails'; Args = @('-Dump', "$work\empty.txt")
+       Exit = 1; Contains = @('No exception classes found') }
+    @{ Name = 'a comma-separated list checks each dump'; Args = @('-Dump', "$work\broken.txt,$work\clean.txt")
+       Exit = 1; Contains = @('broken.txt: 2 exception classes', 'clean.txt: 2 exception classes') }
+    @{ Name = 'a path with a comma stays whole'; Args = @('-Dump', "$work\a dir, with a comma\clean.txt")
+       Exit = 0; Contains = @('clean.txt: 1 exception classes') }
+    @{ Name = 'a build without OrcaSlicer.pdb fails'; Args = @('-BuildDir', $build)
+       Exit = 1; Contains = @('No OrcaSlicer.pdb in') }
+    @{ Name = 'a compiler that is not on PATH is named'; Args = @('-BuildDir', $bare)
+       Exit = 1; Contains = @('no-such-clang-cl.exe, the compiler in') }
+    @{ Name = 'a missing build directory is named'; Args = @('-BuildDir', "$work\nowhere")
+       Exit = 1; Contains = @('No CMakeCache.txt in') }
+    @{ Name = 'no build directory and no dump fails'; Args = @()
+       Exit = 1; Contains = @('Name the slicer build directory') }
+)
+
+$failed = 0
+foreach ($case in $cases) {
+    $ErrorActionPreference = 'Continue'
+    $output = (& powershell -NoProfile -File $check @($case.Args) 2>&1 | Out-String)
+    $code = $LASTEXITCODE
+    $ErrorActionPreference = 'Stop'
+    $problems = @()
+    if ($code -ne $case.Exit) { $problems += "exit $code, expected $($case.Exit)" }
+    foreach ($text in $case.Contains) {
+        if (-not $output.Contains($text)) { $problems += "no '$text' in the output" }
+    }
+    if ($problems) {
+        $failed++
+        "  FAIL $($case.Name)"
+        $problems | ForEach-Object { "       $_" }
+        $output.TrimEnd() -split "`r?`n" | ForEach-Object { "       | $_" }
+    } else {
+        "  ok   $($case.Name)"
+    }
+}
+
+Remove-Item -Recurse -Force $work -ErrorAction SilentlyContinue
+"$($cases.Count - $failed) passed, $failed failed"
+exit [int]($failed -gt 0)