[MichalStrehovsky]

wasmtime with WASMTIME_BACKTRACE_DETAILS=1 can now print the backtrace including line numbers. Locals/parameters are not emitted because RyuJIT seems to be lacking that info.

d:\git\runtime2>wasmtime artifacts\bin\repro\x64\Debug\reproZero.wasm
Hi
Hi
Error: failed to run main module `artifacts\bin\repro\x64\Debug\reproZero.wasm`

Caused by:
    0: failed to invoke command default
    1: error while executing at wasm backtrace:
    0:    0x86d - abort
                    at wasisdk://v34.0/build/sysroot/wasi-libc-wasm32-wasip1-build-prefix/src/wasi-libc-wasm32-wasip1-build-build/wasisdk://v34.0/src/wasi-libc/libc-bottom-half/sources/abort.c:5:3
    1:    0x43b - reproZero_Program__DoAbort
                    at D:\git\runtime2\src\coreclr\tools\aot\ILCompiler\reproZero\zerosharp.cs:164:0
    2:    0x3d5 - reproZero_Program__Main
                    at D:\git\runtime2\src\coreclr\tools\aot\ILCompiler\reproZero\zerosharp.cs:156:0
    3:    0x349 - reproZero_Program__NativeMain
                    at D:\git\runtime2\src\coreclr\tools\aot\ILCompiler\reproZero\zerosharp.cs:141:0
    4:    0x773 - reproZero.wasm!__main_void
    5:    0x2d7 - _start
                    at wasisdk://v34.0/build/sysroot/wasi-libc-wasm32-wasip1-lto-build-prefix/src/wasi-libc-wasm32-wasip1-lto-build-build/wasisdk://v34.0/src/wasi-libc/libc-bottom-half/crt/crt1-command.c:55:11
    2: wasm trap: wasm `unreachable` instruction executed

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
See info in area-owners.md if you want to be subscribed.

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).
13 pipeline(s) were filtered out due to trigger conditions.
There may be pipelines that require an authorized user to comment /azp run to run.

[dotnet-policy-service]

Tagging subscribers to this area: @agocke, @dotnet/ilc-contrib
See info in area-owners.md if you want to be subscribed.

[Copilot]

🟡 Changes recommended

The Wasm writer silently ignores the requested --gdwarf-5 option.

1 open finding

• Wasm writer ignores --gdwarf-5 and always emits DWARF v4 · New

What changed in this PR

Adds DWARF line information to NativeAOT WebAssembly output for source-level Wasmtime backtraces.

Changes:

• Emits DWARF custom sections and Wasm relocations.
• Maps methods and funclets to source locations.
• Adds Wasm-specific DWARF handling.

File	Description
WasmRelocatableObjectWriter.cs	Emits and relocates DWARF sections.
WasmObjectWriter.cs	Creates debug custom sections.
WasmSection.cs	Exposes section prefix sizes.
MethodCodeNode.cs	Restarts mappings for funclets.
DwarfLineSequenceWriter.cs	Completes line sequences correctly.
DwarfInfo.cs	Omits unsupported Wasm frame expressions.
DwarfBuilder.cs	Adds Wasm architecture support.

🧠 Review effort: Balanced

[adamperlin]

@MichalStrehovsky are the line numbers here correct? We had been concerned that IL -> Native offset mappings in the JIT were incorrect on Wasm.

[MichalStrehovsky]

@MichalStrehovsky are the line numbers here correct? We had been concerned that IL -> Native offset mappings in the JIT were incorrect on Wasm.

They looked good for the stack I pasted in top-post.