Compiling Zig from source failing on "newer" dev builds

[emanspeaks]

Zig Version

0.15.0-dev.850+f5a327cd3

Steps to Reproduce and Observed Behavior

I am currently able to build Zig from source successfully for version 0.15.0-dev.646+ef35c3d5f. I last updated my build a month ago and pulled in newer updates this week that seem to break my build. I am still trying to narrow down perhaps where the break happens, and I can update the issue title and description more specifically later once I have further details.

I am building in Windows using the 0.15.0-dev.233+7c85dc460 devkit and using CMake + Ninja, but this seems to not be specific to Windows or this workflow because I have another laptop with the same version of Windows, CMake, and Ninja that IS able to build the latest commit (0.15.0-dev.850+f5a327cd3), so it is something specific to this laptop. This laptop only has 8GB RAM, so I am wondering if there is some issue with build running out of memory but still attempting to proceed for some reason.

To ensure this is actually related to Zig code changes and not some other environmental factor in the last month polluting my build, I rolled the source back to the last known commit that built a month ago listed earlier, and it indeed successfully builds again. Pulling master again yields failure with no useful error message (at least to me) to identify the problem.

Here is relevant output from the build:

C:\zig\build>cmake C:/zig/zig-src -GNinja -DCMAKE_PREFIX_PATH="C:/zig/devkit-0.15.0-dev.233+7c85dc460" -DCMAKE_C_COMPILER="C:/zig/devkit-0.15.0-dev.233+7c85dc460/bin/zig.exe;cc" -DCMAKE_CXX_COMPILER="C:/zig/devkit-0.15.0-dev.233+7c85dc460/bin/zig.exe;c++" -DCMAKE_AR="C:/zig/devkit-0.15.0-dev.233+7c85dc460/bin/zig.exe" -DZIG_AR_WORKAROUND=ON -DZIG_STATIC=ON -DZIG_USE_LLVM_CONFIG=OFF -DCMAKE_BUILD_TYPE=Release -DZIG_NO_LIB=ON   || goto :cmakefail
-- Configuring zig version 0.15.0-dev.850+f5a327cd3
-- Configuring done (1.2s)
-- Generating done (0.2s)
-- Build files have been written to: C:/zig/build

C:\zig\build>ninja install   || goto :ninjafail
[1/2] Building stage3
FAILED: [code=1] stage3/bin/zig C:/zig/build/stage3/bin/zig
C:\WINDOWS\system32\cmd.exe /C "cd /D C:\zig\zig-src && C:\zig\build\zig2.exe build --prefix C:/zig/build/stage3 --zig-lib-dir C:/zig/zig-src/lib -Dversion-string=0.15.0-dev.850+f5a327cd3 -Dtarget=native -Dcpu=native -Denable-llvm -Dconfig_h=C:/zig/build/config.h -Dno-langref -Doptimize=ReleaseFast -Dstrip -Duse-zig-libcxx -Dno-lib"
install
+- install zig
   +- compile exe zig ReleaseFast native failure
error: the following command exited with error code 5:
C:\zig\build\zig2.exe build-exe --stack 48234496 C:\zig\build\zigcpp\libzigcpp.a C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangFrontendTool.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangFrontend.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangDriver.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangSerialization.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangSema.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangStaticAnalyzerFrontend.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangStaticAnalyzerCheckers.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangStaticAnalyzerCore.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangAnalysis.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangASTMatchers.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangAST.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangParse.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangSema.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangAPINotes.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangBasic.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangEdit.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangLex.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangARCMigrate.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangRewriteFrontend.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangRewrite.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangCrossTU.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangIndex.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangToolingCore.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangExtractAPI.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangSupport.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangInstallAPI.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\clangAST.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\lldMinGW.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\lldELF.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\lldCOFF.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\lldWasm.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\lldMachO.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\lldCommon.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWindowsManifest.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMXRay.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLibDriver.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDlltoolDriver.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMTelemetry.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMTextAPIBinaryReader.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMCoverage.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLineEditor.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMXCoreDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMXCoreCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMXCoreDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMXCoreInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMX86TargetMCA.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMX86Disassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMX86AsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMX86CodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMX86Desc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMX86Info.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWebAssemblyDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWebAssemblyAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWebAssemblyCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWebAssemblyUtils.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWebAssemblyDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWebAssemblyInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMVEDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMVEAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMVECodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMVEDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMVEInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSystemZDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSystemZAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSystemZCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSystemZDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSystemZInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSPIRVCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSPIRVDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSPIRVInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSPIRVAnalysis.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSparcDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSparcAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSparcCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSparcDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSparcInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRISCVTargetMCA.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRISCVDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRISCVAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRISCVCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRISCVDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRISCVInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMPowerPCDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMPowerPCAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMPowerPCCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMPowerPCDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMPowerPCInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMNVPTXCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMNVPTXDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMNVPTXInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMSP430Disassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMSP430AsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMSP430CodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMSP430Desc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMSP430Info.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMipsDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMipsAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMipsCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMipsDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMipsInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLoongArchDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLoongArchAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLoongArchCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLoongArchDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLoongArchInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLanaiDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLanaiCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLanaiAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLanaiDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLanaiInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMHexagonDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMHexagonCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMHexagonAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMHexagonDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMHexagonInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBPFDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBPFAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBPFCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBPFDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBPFInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAVRDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAVRAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAVRCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAVRDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAVRInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMARMDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMARMAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMARMCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMARMDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMARMUtils.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMARMInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAMDGPUTargetMCA.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAMDGPUDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAMDGPUAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAMDGPUCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAMDGPUDesc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAMDGPUUtils.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAMDGPUInfo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAArch64Disassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAArch64AsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAArch64CodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAArch64Desc.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAArch64Utils.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAArch64Info.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMOrcDebugging.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMOrcJIT.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMWindowsDriver.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMCJIT.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMJITLink.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMInterpreter.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMExecutionEngine.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRuntimeDyld.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMOrcTargetProcess.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMOrcShared.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDWP.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDebugInfoLogicalView.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDebugInfoGSYM.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMOption.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMObjectYAML.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMObjCopy.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMCA.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMCDisassembler.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLTO.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMPasses.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMHipStdPar.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMCFGuard.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMCoroutines.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMipo.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMVectorize.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSandboxIR.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMLinker.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMInstrumentation.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFrontendOpenMP.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFrontendOffloading.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFrontendOpenACC.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFrontendHLSL.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFrontendDriver.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFrontendAtomic.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMExtensions.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDWARFLinkerParallel.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDWARFLinkerClassic.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDWARFLinker.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMGlobalISel.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMIRParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAsmPrinter.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSelectionDAG.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMCodeGen.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMTarget.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMObjCARCOpts.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMCodeGenTypes.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMCGData.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMIRPrinter.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMInterfaceStub.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFileCheck.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFuzzMutate.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMScalarOpts.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMInstCombine.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAggressiveInstCombine.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMTransformUtils.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBitWriter.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAnalysis.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMProfileData.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSymbolize.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDebugInfoBTF.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDebugInfoPDB.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDebugInfoMSF.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDebugInfoCodeView.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDebugInfoDWARF.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMObject.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMTextAPI.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMCParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMIRReader.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMAsmParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMMC.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBitReader.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMFuzzerCLI.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMCore.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMRemarks.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBitstreamReader.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMBinaryFormat.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMTargetParser.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMSupport.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\LLVMDemangle.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\z.lib C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\zstd.lib -lws2_32 -lversion -lole32 -fstrip -fno-sanitize-thread -OReleaseFast -I C:\zig\devkit-0.15.0-dev.233+7c85dc460\include -I C:\zig\devkit-0.15.0-dev.233+7c85dc460\include -L C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib --dep aro --dep aro_translate_c --dep build_options -Mroot=C:\zig\zig-src\src\main.zig -Maro=C:\zig\zig-src\lib\compiler\aro\aro.zig --dep aro -Maro_translate_c=C:\zig\zig-src\lib\compiler\aro_translate_c.zig -Mbuild_options=C:\zig\build\zig-local-cache\c\c7b871d8866b986352adb267d1f87986\options.zig -lc++ -lc --cache-dir C:\zig\build\zig-local-cache --global-cache-dir C:\zig\build\zig-global-cache --name zig -L C:\zig\devkit-0.15.0-dev.233+7c85dc460\lib -I C:\zig\devkit-0.15.0-dev.233+7c85dc460\include --zig-lib-dir lib\ --listen=-
Build Summary: 1/4 steps succeeded; 1 failed
install transitive failure
+- install zig transitive failure
   +- compile exe zig ReleaseFast native failure
error: the following build command failed with exit code 1:
C:\zig\build\zig-local-cache\o\eca6e8e38b8fe866c9219e247a7f497a\build.exe C:\zig\build\zig2.exe lib C:\zig\zig-src C:\zig\build\zig-local-cache C:\zig\build\zig-global-cache --seed 0x5a20494e -Z5c08bb0dab1426f2 --prefix C:/zig/build/stage3 -Dversion-string=0.15.0-dev.850+f5a327cd3 -Dtarget=native -Dcpu=native -Denable-llvm -Dconfig_h=C:/zig/build/config.h -Dno-langref -Doptimize=ReleaseFast -Dstrip -Duse-zig-libcxx -Dno-lib
ninja: build stopped: subcommand failed.

Clearing caches do not seem to help, and it always dies in the same place trying to build stage3. To see exactly how I am building this in context, I created a repo with a script that runs these commands in an isolated sandbox.

Any help on troubleshooting this build or isolating the problem would be helpful. Trying to just compare the two commit diffs was not fruitful since 2k files have changed in the last month, seemingly related to the transition away from LLVM x86_64 backend, making it a little harder to isolate. It also takes a considerable amount of time to build, so I would prefer to not just walk back one commit at a time to isolate things if anyone has wisdom on where I could focus.

Expected Behavior

Expected Zig stage3 to build successfully with latest commits since it does both in CI pipelines here and on another Windows laptop running these same exact scripts from my build repo.

[jacobly0]

Windows changes from #24193 have not even landed yet, what msvc version do you have installed?

[emanspeaks]

I am not using MSVC; Zig is bootstrapping itself with zig cc based on the pre-built one in the devkit as described here

[jacobly0]

Without more information about the crash, such as the disassembly near the crash, my best guess is that you are hitting 45700b8 in some cpu count/model-specific way.

[emanspeaks]

Yeah, I hate not providing more info, but I don't know enough currently about the build process to know what to share that might be useful. I'm fairly new to Zig, so not sure how to even go about getting disassembly info and had hoped that I'd just get a traceback or something from the error message itself, alas...can you point me to a resource that tells me how to better help me help you?

[jacobly0]

In the middle of your error output you see error: the following command exited with error code 5: (not the one at the end with code 1), the next line is the command you would run in a debugger to see where it is crashing, although you have to remove the --listen=- argument first. You would probably want to rerun the cmake command with -DCMAKE_BUILD_TYPE=RelWithDebInfo instead of Release to get a zig2.exe with debug info first.

[emanspeaks]

Okay, now we're cooking. I have yet to be able to actually "catch" problem with an exception or traceback or something, but in four runs, I have twice gotten BSODs with CLOCK_WATCHDOG_TIMEOUT errors, once just got a machine freeze, and one of the times I was able to still have some life in the machine and managed to snag this from the terminal output:

[7584/14650] Linking
[7575/12819] Code Generation
[38295] Semantic Analysis
└─ arch.x86_64.Encoding.findByMnemonic

At least one of the other times before BSODing, I noticed this was roughly the same text in the console (although can't be certain the numbers were exactly the same as this sample; not sure how deterministic the linker is).

I also watched a system resource monitor, and neither the RAM nor Swap are peaking when we hit the problem, nor is the CPU even seemingly all that overloaded like it can be during compilation.

The BSOD message, upon searching online, does seem to imply that it has to do with different CPU cores getting out of sync, which I could see happening if one thread had some bad/unexpected instruction that perhaps a more robust machine than this very weak laptop could handle gracefully? I think people often get these sorts of messages when they overclock their CPU and it is running unstable, but I haven't changed anything on this laptop from its stock factory settings. It's also strange to me this would happen during linking and not during compilation, and that it only seems to be happening when I switch to more recent commits and goes away when I revert back to commits in May.

Hopefully there is some breadcrumb there that might help guide me to something more useful to try in tracking this down. This seems quite repeatable on this machine, so I don't think it's a coincidence. Happy to keep at this and try adding a breakpoint or something, I'm just still not sure where is an appropriate place to do so, especially since I still haven't trapped the problem exactly.

[jacobly0]

BSOD means hardware/driver issue (or OOM, but you say that isn't happening), not a bug in the compiler. Depending on the type of failure, something like reducing threads with -j may help, by avoiding triggering the hardware failure mode, but in general there's nothing I can do in software to make faulty hardware magically function.

[emanspeaks]

Ah, I just figured out those crashes were caused by the debugger not being configured correctly. This time, I managed to catch the exception.

Call stack:

zig2.exe!InternPool_Index_Unwrapped_getItem__57905(const InternPool_Index_Unwrapped__86793 a0, const InternPool__7589 * const a1) Line 624003 (c:\zig\build\zig2.c:624003)
zig2.exe!InternPool_indexToKey__9362(const InternPool__7589 * const a0, const unsigned int a1) Line 538904 (c:\zig\build\zig2.c:538904)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935780 (c:\zig\build\zig2.c:1935780)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935923 (c:\zig\build\zig2.c:1935923)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935923 (c:\zig\build\zig2.c:1935923)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935923 (c:\zig\build\zig2.c:1935923)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935837 (c:\zig\build\zig2.c:1935837)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935878 (c:\zig\build\zig2.c:1935878)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935923 (c:\zig\build\zig2.c:1935923)
zig2.exe!Sema_checkRuntimeValue__91628(Sema__234447 * const a0, const unsigned int a1) Line 2973429 (c:\zig\build\zig2.c:2973429)
zig2.exe!Sema_validateRuntimeValue__91629(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2453943 (c:\zig\build\zig2.c:2453943)
zig2.exe!Sema_elemValArray__91497(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const Zcu_LazySrcLoc__9714 a3, const unsigned int a4, const Zcu_LazySrcLoc__9714 a5, const unsigned int a6, const bool a7) Line 2459054 (c:\zig\build\zig2.c:2459054)
zig2.exe!Sema_elemVal__91493(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3, const unsigned int a4, const Zcu_LazySrcLoc__9714 a5, const bool a6) Line 2885807 (c:\zig\build\zig2.c:2885807)
zig2.exe!Sema_zirElemValNode__91215(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2365698 (c:\zig\build\zig2.c:2365698)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1909591 (c:\zig\build\zig2.c:1909591)
zig2.exe!Sema_analyzeFnBody__91002(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1542339 (c:\zig\build\zig2.c:1542339)
zig2.exe!Zcu_PerThread_analyzeFnBodyInner__8577(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1543372 (c:\zig\build\zig2.c:1543372)
zig2.exe!Zcu_PerThread_analyzeFuncBody__8561(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1145268 (c:\zig\build\zig2.c:1145268)
zig2.exe!Zcu_PerThread_ensureFuncBodyUpToDate__8560(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 860427 (c:\zig\build\zig2.c:860427)
zig2.exe!Sema_resolveInferredErrorSet__91583(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2454222 (c:\zig\build\zig2.c:2454222)
zig2.exe!Sema_analyzeIsNonErrComptimeOnly__91547(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2441383 (c:\zig\build\zig2.c:2441383)
zig2.exe!Sema_zirTry__91318(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2440693 (c:\zig\build\zig2.c:2440693)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1913151 (c:\zig\build\zig2.c:1913151)
zig2.exe!Sema_resolveBlockBody__91127(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, Sema_Block__235607 * const a3, const anon__lazy_1648 a4, const unsigned int a5, Sema_Block_Merges__235630 * const a6) Line 2915143 (c:\zig\build\zig2.c:2915143)
zig2.exe!Sema_zirBlock__91126(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2438196 (c:\zig\build\zig2.c:2438196)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1912626 (c:\zig\build\zig2.c:1912626)
zig2.exe!Sema_analyzeBodyRuntimeBreak__91001(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 2378928 (c:\zig\build\zig2.c:2378928)
zig2.exe!Sema_SwitchProngAnalysis_analyzeProngRuntime__116270(const Sema_SwitchProngAnalysis__476660 a0, Sema_Block__235607 * const a1, const unsigned char a2, const anon__lazy_1648 a3, const unsigned char a4, const Zcu_LazySrcLoc__9714 a5, const anon__lazy_1648 a6, const unsigned int a7, const bool a8) Line 3383993 (c:\zig\build\zig2.c:3383993)
zig2.exe!Sema_analyzeSwitchRuntimeBlock__91231(Sema__234447 * const a0, const Sema_SwitchProngAnalysis__476660 a1, Sema_Block__235607 * const a2, const Zcu_LazySrcLoc__9714 a3, const unsigned int a4, const Type__7880 a5, const Zcu_LazySrcLoc__9714 a6, const array_list_ArrayListAlignedUnmanaged_28Air_Inst_Ref_2cnull_29__235632 a7, const Sema_SpecialProng__476691 a8, const unsigned __int64 a9, const unsigned __int64 a10, const bool a11, const Type__7880 a12, const bool a13, const int a14, const Zcu_LazySrcLoc__9714 a15, const anon__lazy_33614 a16, const hash_map_HashMap_28InternPool_NullTerminatedString_2cZcu_LazySrcLoc_2chash_map_AutoContext_28InternPool_NullTerminatedString_29_2c80_29__476696 a17, const RangeSet__476714 a18, const unsigned char a19, const unsigned char a20, const unsigned int a21, const bool a22) Line 2914750 (c:\zig\build\zig2.c:2914750)
zig2.exe!Sema_zirSwitchBlock__91229(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2, const bool a3) Line 2378495 (c:\zig\build\zig2.c:2378495)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1910185 (c:\zig\build\zig2.c:1910185)
zig2.exe!Sema_analyzeFnBody__91002(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1542339 (c:\zig\build\zig2.c:1542339)
zig2.exe!Zcu_PerThread_analyzeFnBodyInner__8577(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1543372 (c:\zig\build\zig2.c:1543372)
zig2.exe!Zcu_PerThread_analyzeFuncBody__8561(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1145268 (c:\zig\build\zig2.c:1145268)
zig2.exe!Zcu_PerThread_ensureFuncBodyUpToDate__8560(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 860427 (c:\zig\build\zig2.c:860427)
zig2.exe!Sema_resolveInferredErrorSet__91583(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2454222 (c:\zig\build\zig2.c:2454222)
zig2.exe!Sema_analyzeIsNonErrComptimeOnly__91547(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2441383 (c:\zig\build\zig2.c:2441383)
zig2.exe!Sema_analyzeIsNonErr__91548(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2902803 (c:\zig\build\zig2.c:2902803)
zig2.exe!Sema_zirIsNonErr__91314(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2370098 (c:\zig\build\zig2.c:2370098)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1909921 (c:\zig\build\zig2.c:1909921)
zig2.exe!Sema_resolveBlockBody__91127(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, Sema_Block__235607 * const a3, const anon__lazy_1648 a4, const unsigned int a5, Sema_Block_Merges__235630 * const a6) Line 2915143 (c:\zig\build\zig2.c:2915143)
zig2.exe!Sema_zirBlock__91126(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2438196 (c:\zig\build\zig2.c:2438196)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1912626 (c:\zig\build\zig2.c:1912626)
zig2.exe!Sema_analyzeBodyRuntimeBreak__91001(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 2378928 (c:\zig\build\zig2.c:2378928)
zig2.exe!Sema_SwitchProngAnalysis_analyzeProngRuntime__116270(const Sema_SwitchProngAnalysis__476660 a0, Sema_Block__235607 * const a1, const unsigned char a2, const anon__lazy_1648 a3, const unsigned char a4, const Zcu_LazySrcLoc__9714 a5, const anon__lazy_1648 a6, const unsigned int a7, const bool a8) Line 3383993 (c:\zig\build\zig2.c:3383993)
zig2.exe!Sema_analyzeSwitchRuntimeBlock__91231(Sema__234447 * const a0, const Sema_SwitchProngAnalysis__476660 a1, Sema_Block__235607 * const a2, const Zcu_LazySrcLoc__9714 a3, const unsigned int a4, const Type__7880 a5, const Zcu_LazySrcLoc__9714 a6, const array_list_ArrayListAlignedUnmanaged_28Air_Inst_Ref_2cnull_29__235632 a7, const Sema_SpecialProng__476691 a8, const unsigned __int64 a9, const unsigned __int64 a10, const bool a11, const Type__7880 a12, const bool a13, const int a14, const Zcu_LazySrcLoc__9714 a15, const anon__lazy_33614 a16, const hash_map_HashMap_28InternPool_NullTerminatedString_2cZcu_LazySrcLoc_2chash_map_AutoContext_28InternPool_NullTerminatedString_29_2c80_29__476696 a17, const RangeSet__476714 a18, const unsigned char a19, const unsigned char a20, const unsigned int a21, const bool a22) Line 2912740 (c:\zig\build\zig2.c:2912740)
zig2.exe!Sema_zirSwitchBlock__91229(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2, const bool a3) Line 2378495 (c:\zig\build\zig2.c:2378495)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1910185 (c:\zig\build\zig2.c:1910185)
zig2.exe!Sema_analyzeFnBody__91002(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1542339 (c:\zig\build\zig2.c:1542339)
zig2.exe!Zcu_PerThread_analyzeFnBodyInner__8577(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1543372 (c:\zig\build\zig2.c:1543372)
zig2.exe!Zcu_PerThread_analyzeFuncBody__8561(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1145268 (c:\zig\build\zig2.c:1145268)
zig2.exe!Zcu_PerThread_ensureFuncBodyUpToDate__8560(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 860427 (c:\zig\build\zig2.c:860427)
zig2.exe!Compilation_processOneJob__3978(const unsigned __int64 a0, Compilation__3107 * const a1, const Compilation_Job__7586 a2) Line 620392 (c:\zig\build\zig2.c:620392)
zig2.exe!Compilation_performAllTheWork__3974(Compilation__3107 * const a0, const Progress_Node__2865 a1) Line 536991 (c:\zig\build\zig2.c:536991)
zig2.exe!Compilation_update__3951(Compilation__3107 * const a0, const Progress_Node__2865 a1) Line 476795 (c:\zig\build\zig2.c:476795)
zig2.exe!main_updateModule__296(Compilation__3107 * const a0, const unsigned char a1, const Progress_Node__2865 a2) Line 488915 (c:\zig\build\zig2.c:488915)
zig2.exe!main_buildOutputType__288(const mem_Allocator__2067 a0, const mem_Allocator__2067 a1, const anon__lazy_977 a2, const main_ArgMode__2700 a3) Line 497079 (c:\zig\build\zig2.c:497079)
zig2.exe!main_mainArgs__278(const mem_Allocator__2067 a0, const mem_Allocator__2067 a1, const anon__lazy_977 a2) Line 500179 (c:\zig\build\zig2.c:500179)
zig2.exe!main_main__276() Line 448210 (c:\zig\build\zig2.c:448210)
zig2.exe!main(const int a0, char * * const a1, char * * const a2) Line 447938 (c:\zig\build\zig2.c:447938)
zig2.exe!__tmainCRTStartup() Line 266 (c:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\zig\libc\mingw\crt\crtexe.c:266)
zig2.exe!mainCRTStartup() Line 188 (c:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\zig\libc\mingw\crt\crtexe.c:188)
kernel32.dll!00007ff9b7cde8d7() (Unknown Source:0)
ntdll.dll!00007ff9b92dc34c() (Unknown Source:0)

Exception:

Exception has occurred: W32/0xC0000005
Unhandled exception at 0x00007FF6E694CD52 in zig2.exe: 0xC0000005: Access violation reading location 0x00000000000F2612.

The line of code in question is in this function:

static struct InternPool_Item__9956 InternPool_Index_Unwrapped_getItem__57905(struct InternPool_Index_Unwrapped__86793 const a0, struct InternPool__7589 const *const a1) {
 struct InternPool_Index_Unwrapped__86793 const *t1;
 struct InternPool_Index_Unwrapped_ItemPtr__112581 t3;
 uint8_t *t4;
 uint8_t const *t5;
 uint32_t *t8;
 uint32_t *t9;
 struct InternPool_Index_Unwrapped__86793 t2;
 struct InternPool_Index_Unwrapped__86793 t0;
 uint32_t t10;
 struct InternPool_Item__9956 t7;
 uint8_t t6;
 t0 = a0;
 t1 = (struct InternPool_Index_Unwrapped__86793 const *)&t0;
 t2 = (*t1);
 t3 = InternPool_Index_Unwrapped_itemPtr__57909(t2, a1);
 t4 = t3.tag_ptr;
 t5 = (uint8_t const *)t4;
 zig_atomic_load(t6, (zig_atomic(uint8_t) *)t5, zig_memory_order_acquire, u8, uint8_t);  // this is where the exception is thrown
 t4 = (uint8_t *)&t7.tag;
 (*t4) = t6;
 t8 = (uint32_t *)&t7.data;
 t9 = t3.data_ptr;
 t10 = (*t9);
 (*t8) = t10;
 return t7;
}

[emanspeaks]

It happens at a slightly different place on second run:

zig2.exe!multi_array_list_MultiArrayList_28struct_20_7b_20u32_20_7d_29_items__anon_86959__57959(const multi_array_list_MultiArrayList_28struct_20_7b_20u32_20_7d_29__86937 a0) Line 624225 (c:\zig\build\zig2.c:624225)
zig2.exe!InternPool_loadStructType__9319(const InternPool__7589 * const a0, const unsigned int a1) Line 585111 (c:\zig\build\zig2.c:585111)
zig2.exe!InternPool_aggregateTypeLenIncludingSentinel__9463(const InternPool__7589 * const a0, const unsigned int a1) Line 625421 (c:\zig\build\zig2.c:625421)
zig2.exe!InternPool_indexToKey__9362(const InternPool__7589 * const a0, const unsigned int a1) Line 540380 (c:\zig\build\zig2.c:540380)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935780 (c:\zig\build\zig2.c:1935780)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935923 (c:\zig\build\zig2.c:1935923)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935837 (c:\zig\build\zig2.c:1935837)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935878 (c:\zig\build\zig2.c:1935878)
zig2.exe!Value_canMutateComptimeVarState__57717(const Value__86471 a0, Zcu__3254 * const a1) Line 1935923 (c:\zig\build\zig2.c:1935923)
zig2.exe!Sema_resolveFinalDeclValue__91024(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 1546430 (c:\zig\build\zig2.c:1546430)
zig2.exe!Zcu_PerThread_analyzeNavVal__8557(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1148542 (c:\zig\build\zig2.c:1148542)
zig2.exe!Zcu_PerThread_ensureNavValUpToDate__8556(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 861272 (c:\zig\build\zig2.c:861272)
zig2.exe!Sema_ensureNavResolved__91535(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3, const unsigned char a4) Line 1547665 (c:\zig\build\zig2.c:1547665)
zig2.exe!Sema_analyzeNavRefInner__91538(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3, const bool a4) Line 2469492 (c:\zig\build\zig2.c:2469492)
zig2.exe!Sema_analyzeNavVal__91531(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 1941720 (c:\zig\build\zig2.c:1941720)
zig2.exe!Sema_zirDeclVal__91143(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2365295 (c:\zig\build\zig2.c:2365295)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1909536 (c:\zig\build\zig2.c:1909536)
zig2.exe!Sema_analyzeFnBody__91002(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1542339 (c:\zig\build\zig2.c:1542339)
zig2.exe!Zcu_PerThread_analyzeFnBodyInner__8577(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1543372 (c:\zig\build\zig2.c:1543372)
zig2.exe!Zcu_PerThread_analyzeFuncBody__8561(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1145268 (c:\zig\build\zig2.c:1145268)
zig2.exe!Zcu_PerThread_ensureFuncBodyUpToDate__8560(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 860427 (c:\zig\build\zig2.c:860427)
zig2.exe!Sema_resolveInferredErrorSet__91583(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2454222 (c:\zig\build\zig2.c:2454222)
zig2.exe!Sema_analyzeIsNonErrComptimeOnly__91547(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2441383 (c:\zig\build\zig2.c:2441383)
zig2.exe!Sema_zirTry__91318(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2440693 (c:\zig\build\zig2.c:2440693)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1913151 (c:\zig\build\zig2.c:1913151)
zig2.exe!Sema_resolveBlockBody__91127(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, Sema_Block__235607 * const a3, const anon__lazy_1648 a4, const unsigned int a5, Sema_Block_Merges__235630 * const a6) Line 2915143 (c:\zig\build\zig2.c:2915143)
zig2.exe!Sema_zirBlock__91126(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2438196 (c:\zig\build\zig2.c:2438196)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1912626 (c:\zig\build\zig2.c:1912626)
zig2.exe!Sema_analyzeBodyRuntimeBreak__91001(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 2378928 (c:\zig\build\zig2.c:2378928)
zig2.exe!Sema_SwitchProngAnalysis_analyzeProngRuntime__116270(const Sema_SwitchProngAnalysis__476660 a0, Sema_Block__235607 * const a1, const unsigned char a2, const anon__lazy_1648 a3, const unsigned char a4, const Zcu_LazySrcLoc__9714 a5, const anon__lazy_1648 a6, const unsigned int a7, const bool a8) Line 3383993 (c:\zig\build\zig2.c:3383993)
zig2.exe!Sema_analyzeSwitchRuntimeBlock__91231(Sema__234447 * const a0, const Sema_SwitchProngAnalysis__476660 a1, Sema_Block__235607 * const a2, const Zcu_LazySrcLoc__9714 a3, const unsigned int a4, const Type__7880 a5, const Zcu_LazySrcLoc__9714 a6, const array_list_ArrayListAlignedUnmanaged_28Air_Inst_Ref_2cnull_29__235632 a7, const Sema_SpecialProng__476691 a8, const unsigned __int64 a9, const unsigned __int64 a10, const bool a11, const Type__7880 a12, const bool a13, const int a14, const Zcu_LazySrcLoc__9714 a15, const anon__lazy_33614 a16, const hash_map_HashMap_28InternPool_NullTerminatedString_2cZcu_LazySrcLoc_2chash_map_AutoContext_28InternPool_NullTerminatedString_29_2c80_29__476696 a17, const RangeSet__476714 a18, const unsigned char a19, const unsigned char a20, const unsigned int a21, const bool a22) Line 2914750 (c:\zig\build\zig2.c:2914750)
zig2.exe!Sema_zirSwitchBlock__91229(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2, const bool a3) Line 2378495 (c:\zig\build\zig2.c:2378495)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1910185 (c:\zig\build\zig2.c:1910185)
zig2.exe!Sema_analyzeFnBody__91002(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1542339 (c:\zig\build\zig2.c:1542339)
zig2.exe!Zcu_PerThread_analyzeFnBodyInner__8577(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1543372 (c:\zig\build\zig2.c:1543372)
zig2.exe!Zcu_PerThread_analyzeFuncBody__8561(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1145268 (c:\zig\build\zig2.c:1145268)
zig2.exe!Zcu_PerThread_ensureFuncBodyUpToDate__8560(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 860427 (c:\zig\build\zig2.c:860427)
zig2.exe!Sema_resolveInferredErrorSet__91583(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2454222 (c:\zig\build\zig2.c:2454222)
zig2.exe!Sema_analyzeIsNonErrComptimeOnly__91547(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2441383 (c:\zig\build\zig2.c:2441383)
zig2.exe!Sema_analyzeIsNonErr__91548(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, const unsigned int a3) Line 2902803 (c:\zig\build\zig2.c:2902803)
zig2.exe!Sema_zirIsNonErr__91314(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2370098 (c:\zig\build\zig2.c:2370098)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1909921 (c:\zig\build\zig2.c:1909921)
zig2.exe!Sema_resolveBlockBody__91127(Sema__234447 * const a0, Sema_Block__235607 * const a1, const Zcu_LazySrcLoc__9714 a2, Sema_Block__235607 * const a3, const anon__lazy_1648 a4, const unsigned int a5, Sema_Block_Merges__235630 * const a6) Line 2915143 (c:\zig\build\zig2.c:2915143)
zig2.exe!Sema_zirBlock__91126(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2) Line 2438196 (c:\zig\build\zig2.c:2438196)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1912626 (c:\zig\build\zig2.c:1912626)
zig2.exe!Sema_analyzeBodyRuntimeBreak__91001(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 2378928 (c:\zig\build\zig2.c:2378928)
zig2.exe!Sema_SwitchProngAnalysis_analyzeProngRuntime__116270(const Sema_SwitchProngAnalysis__476660 a0, Sema_Block__235607 * const a1, const unsigned char a2, const anon__lazy_1648 a3, const unsigned char a4, const Zcu_LazySrcLoc__9714 a5, const anon__lazy_1648 a6, const unsigned int a7, const bool a8) Line 3383993 (c:\zig\build\zig2.c:3383993)
zig2.exe!Sema_analyzeSwitchRuntimeBlock__91231(Sema__234447 * const a0, const Sema_SwitchProngAnalysis__476660 a1, Sema_Block__235607 * const a2, const Zcu_LazySrcLoc__9714 a3, const unsigned int a4, const Type__7880 a5, const Zcu_LazySrcLoc__9714 a6, const array_list_ArrayListAlignedUnmanaged_28Air_Inst_Ref_2cnull_29__235632 a7, const Sema_SpecialProng__476691 a8, const unsigned __int64 a9, const unsigned __int64 a10, const bool a11, const Type__7880 a12, const bool a13, const int a14, const Zcu_LazySrcLoc__9714 a15, const anon__lazy_33614 a16, const hash_map_HashMap_28InternPool_NullTerminatedString_2cZcu_LazySrcLoc_2chash_map_AutoContext_28InternPool_NullTerminatedString_29_2c80_29__476696 a17, const RangeSet__476714 a18, const unsigned char a19, const unsigned char a20, const unsigned int a21, const bool a22) Line 2912740 (c:\zig\build\zig2.c:2912740)
zig2.exe!Sema_zirSwitchBlock__91229(Sema__234447 * const a0, Sema_Block__235607 * const a1, const unsigned int a2, const bool a3) Line 2378495 (c:\zig\build\zig2.c:2378495)
zig2.exe!Sema_analyzeBodyInner__91005(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1910185 (c:\zig\build\zig2.c:1910185)
zig2.exe!Sema_analyzeFnBody__91002(Sema__234447 * const a0, Sema_Block__235607 * const a1, const anon__lazy_1648 a2) Line 1542339 (c:\zig\build\zig2.c:1542339)
zig2.exe!Zcu_PerThread_analyzeFnBodyInner__8577(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1543372 (c:\zig\build\zig2.c:1543372)
zig2.exe!Zcu_PerThread_analyzeFuncBody__8561(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 1145268 (c:\zig\build\zig2.c:1145268)
zig2.exe!Zcu_PerThread_ensureFuncBodyUpToDate__8560(const Zcu_PerThread__7066 a0, const unsigned int a1) Line 860427 (c:\zig\build\zig2.c:860427)
zig2.exe!Compilation_processOneJob__3978(const unsigned __int64 a0, Compilation__3107 * const a1, const Compilation_Job__7586 a2) Line 620392 (c:\zig\build\zig2.c:620392)
zig2.exe!Compilation_performAllTheWork__3974(Compilation__3107 * const a0, const Progress_Node__2865 a1) Line 536991 (c:\zig\build\zig2.c:536991)
zig2.exe!Compilation_update__3951(Compilation__3107 * const a0, const Progress_Node__2865 a1) Line 476795 (c:\zig\build\zig2.c:476795)
zig2.exe!main_updateModule__296(Compilation__3107 * const a0, const unsigned char a1, const Progress_Node__2865 a2) Line 488915 (c:\zig\build\zig2.c:488915)
zig2.exe!main_buildOutputType__288(const mem_Allocator__2067 a0, const mem_Allocator__2067 a1, const anon__lazy_977 a2, const main_ArgMode__2700 a3) Line 497079 (c:\zig\build\zig2.c:497079)
zig2.exe!main_mainArgs__278(const mem_Allocator__2067 a0, const mem_Allocator__2067 a1, const anon__lazy_977 a2) Line 500179 (c:\zig\build\zig2.c:500179)
zig2.exe!main_main__276() Line 448210 (c:\zig\build\zig2.c:448210)
zig2.exe!main(const int a0, char * * const a1, char * * const a2) Line 447938 (c:\zig\build\zig2.c:447938)
zig2.exe!__tmainCRTStartup() Line 266 (c:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\zig\libc\mingw\crt\crtexe.c:266)
zig2.exe!mainCRTStartup() Line 188 (c:\zig\devkit-0.15.0-dev.233+7c85dc460\lib\zig\libc\mingw\crt\crtexe.c:188)
kernel32.dll!00007ff9b7cde8d7() (Unknown Source:0)
ntdll.dll!00007ff9b92dc34c() (Unknown Source:0)

Both times the output in console reads

[7584/14649] Linking
[7575/12819] Code Generation
[38294] Semantic Analysis
└─ arch.x86_64.Encoding.mnemonic_to_encodin

when the exception is raised.

Given the condition happens at a different place in the code, but still seemingly associated with the same point in the build consistently, it could be a race condition as previously mentioned or, perhaps as mentioned in the closure message, some hardware/driver/non-Zig issue triggered by something that just happens to be related to linker steps around Encoding (I conceded in my original message it seems unique to this machine so I accepted that could be the conclusion). I still find it rather suspicious that this build was successful before on this machine and suddenly now is not, but perhaps this problem will resolve itself in the future after other regressions are addressed. Until then, I can just build on other machines and copy to this one, though less ideal.

[jacobly0]

That's not really enough information to rule a stack overflow in or out, what happens if you mess with the numbers here or here? Say, add a 0 to both (idk which one your build uses).

[emanspeaks]

(I am using MinGW for all intents and purposes here)

Interesting. I tried changing both the zig1 and zig2 stack values in separate runs, both failed. But I noticed in the command that is failing both times still started out "C:\\zig\\build\\zig2.exe" build-exe --stack 48234496 with that same number...which is not the decimal equivalent of either the original value in CMake or the modified ones. In fact, if you scroll to the top, it's the same number as the original. But I am looking at the build.ninja file and do see indeed that those values are updating as I change them in CMake. Is this value getting overflowed in Zig and not actually updating the ultimate constructed system calls? Or does it modify the number it's given prior to constructing this call to zig2?

So, in my zig2 debug launcher, I changed that stack value and added a zero to the end so now the command starts with "C:\\zig\\build\\zig2.exe" build-exe --stack 482344960. Lo and behold...it still seemed to really think hard when it worked through the Encoding link steps (specifically the arch.x86_64.Encoding.mnemonic_to_encodin and arch.x86_64.Encoding.findByMnemonic seem to be a real struggle), but this time it got past them. It still died, but did so elsewhere much closer to the finish line.

I increased that value with one additional zero (to now read 4823449600), and now it is failing again in the same place as before. I have also only sporadically had success trying to change that stack value in the zig2 line, but never quite ever completing without hitting an access violation exception. (No more BSODs, though, but it can still cause the whole machine to hang for a few minutes on occasion).

If I had to guess, there is some sort of stack overflow or something happening like some race condition like you have speculated previously, but still struggling to find what or where it is.

I resigned to just doing what I was hoping to avoid and started trying to walk commits backward a few at a time "cleverly" looking at the graph to identify milestones to try. If I can find the commit where things go off the rails, I think it will be much easier to narrow down what's happening. I'm ok if the answer is still just that it's a hardware issue on my end, but I'm still going to keep at this to try to at least find the cause. If you want to close this issue again, I'm ok with that and can create a new one later if and when I have more info.