Stop debug tslang --emit=exe/dll ending in a breakpoint at exit - #326
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A debug tslang turns on the CRT leak report at exit (_CRTDBG_LEAK_CHECK_DF), which is emitted as a _CRT_WARN report. Building an exe or dll constructs llvm::InitLLVM (exe.cpp), whose PrintStackTraceOnErrorSignal installs LLVM's AvoidMessageBoxHook with _CrtSetReportHook. That hook answers every CRT report with "retry", and the report macro turns a retry into _CrtDbgBreak - so every debug --emit=exe and --emit=dll ended with an unhandled breakpoint (0x80000003, exit code 3) after the output had been written. The heap was not corrupted: periodic _CrtCheckMemory during the build stayed clean. The JIT installs the same hook but exits through TerminateProcess, and --emit=obj never installs it. Install a _CrtSetReportHook2 hook for _CRT_WARN that writes the message to the debugger output (where it went before) and does not ask to break. Report hooks from _CrtSetReportHook2 run before the _CrtSetReportHook one (ucrt dbgrptt.cpp), so asserts and errors still reach LLVM's hook. Fixes test-compile-gc-shared-auto and test-jit-gc-defaultlib-collector on debug builds (CI builds Release, where the leak check does not exist). Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Problem
In a Debug build, every
tslang --emit=exe/--emit=dllrun ended in a breakpoint exception (0x80000003) at process exit. This failedtest-compile-gc-shared-autoandtest-jit-gc-defaultlib-collector, and was half oftest-compile-gc-defaultlib-collector. CI builds Release only, so it never showed there.Root cause
tslang.cppenables_CRTDBG_LEAK_CHECK_DF, so the debug CRT emits a_CRT_WARNleak report at exit.buildExeconstructsllvm::InitLLVM, which (viaDisableSystemDialogsOnCrash) installs LLVM'sAvoidMessageBoxHookwith_CrtSetReportHook. That hook answers every report with "retry"._CrtDbgBreak, so the harmless leak report became an int3.JIT exits via
TerminateProcessand never reports;--emit=objnever installs LLVM's hook.Fix
Install a
_CrtSetReportHook2hook inmain(Debug MSVC only) that handles_CRT_WARNitself: it forwards the text toOutputDebugStringAand returns without asking for a break. v2 hooks run before the v1 hook (ucrtdbgrptt.cpp), so LLVM's hook never sees warnings. Errors and asserts are untouched.Verification (windows-msbuild-2026-debug)
--emit=dll/--emit=exeexit 0.test-compile-gc-shared-autoandtest-jit-gc-defaultlib-collectorpass.test-compile-gc-defaultlib-collectorpasses together with TypeScriptCompilerDefaultLib#7 (debug wrappers built with/MTd) and a rebuilt debug default lib.ctest -R "^test-", 2727 tests): onlytest-jit-rc-owned-array-opsandtest-compile-rc-corpus-00owned-array-opsfail, both fixed by Fix memmove sizes in array shift, unshift and splice #325 which is not in this branch.🤖 Generated with Claude Code