rts: handle R_*_NONE-only undefined symbols (leftover from nix-ci-split) by angerman · Pull Request #163 · stable-haskell/ghc

angerman · 2026-03-02T03:01:16Z

Summary

Retargeted after stable-ghc-9.14 cutover (was rebased onto a4f2bdf).

Most of the original PR (Makefile cross-build support, Nix CI build/test/cross split, stamp-as-Make-target / PHONY order-only fixes) is now carried by #181 (feat/wasm-cross-ghcup) in a form adapted to the post-9.14.2 Makefile / nix-ci.yml.

Remaining unique commit on this PR

rts: handle undefined symbols referenced only by R_*_NONE relocations (rts/linker/elf_got.c) — fixes reloc-none on aarch64-linux with GCC 13/14.

Superseded by #181 (do not re-land here)

Makefile WASM/JS cross-build / dist configuration
nix-ci.yml Build / Test / Cross matrix
Stamp-file Make targets + PHONY order-only / hackage race fixes

Test plan

CI green on new stable-ghc-9.14
Confirm reloc-none / related linker tests on aarch64-linux if available

Copilot

Pull request overview

This PR restructures GitHub Actions CI for the Nix-based build to split build/test, add aarch64-linux coverage, and validate cross-backend builds (JS/WASM) using dist artifacts, while temporarily disabling the release workflow during the transition.

Changes:

Replaces the old monolithic CI workflow with nix-ci.yml, splitting each matrix entry into separate build and test jobs with uploaded artifacts.
Adds CI coverage for aarch64-linux plus a new dynamic matrix dimension, and introduces cross-js / cross-wasm jobs from the dist artifact.
Updates the Makefile to support dist-based cross builds via configurable GHC_TOOLCHAIN_BIN and HAPPY_TEMPLATE_DIR.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
Makefile	Adds knobs and bindist contents needed to build cross targets from downloaded dist artifacts.
.github/workflows/nix-ci.yml	New CI workflow with split build/test, expanded matrix, and cross-backend jobs.
.github/workflows/release.yml	Temporarily disables release workflow execution.
.github/workflows/ci.yml	Removes the old CI workflow in favor of the new Nix CI.

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Copilot · 2026-03-02T03:08:01Z

+  test:
+    name: "Test / ${{ matrix.plat }} / dynamic=${{ matrix.dynamic }}"
+    needs: build
+    runs-on: "${{ fromJSON('{\"x86_64-linux\": \"ubuntu-24.04\", \"aarch64-linux\": \"ubuntu-24.04-arm\", \"aarch64-darwin\": \"macos-latest\"}')[matrix.plat] }}"


needs: build on a matrix job will block every test run until all build matrix runs finish, which reduces parallelism and can significantly lengthen end-to-end CI time. If the intent is for each (plat,dynamic) test to start as soon as its matching build artifact is uploaded, consider restructuring into explicit per-entry build jobs (e.g., via a reusable workflow invoked once per include entry) so each test job can needs: its corresponding build job, rather than the whole build matrix.

Copilot · 2026-03-02T03:08:02Z

+  cross-js:
+    name: "Cross: JS / x86_64-linux"
+    needs: build


Both cross jobs only consume x86_64-linux-dynamic0-dist, but needs: build will wait for the entire build matrix to complete before starting. To avoid unnecessary delays, consider introducing a dedicated build job for x86_64-linux dynamic=0 (or splitting the build matrix into per-entry jobs) and have cross-js / cross-wasm depend only on that specific job.

Copilot · 2026-03-02T03:08:02Z

+  cross-wasm:
+    name: "Cross: WASM / x86_64-linux"
+    needs: build


Both cross jobs only consume x86_64-linux-dynamic0-dist, but needs: build will wait for the entire build matrix to complete before starting. To avoid unnecessary delays, consider introducing a dedicated build job for x86_64-linux dynamic=0 (or splitting the build matrix into per-entry jobs) and have cross-js / cross-wasm depend only on that specific job.

Copilot · 2026-03-02T03:08:02Z

+        curl -fsSL https://gitlab.haskell.org/ghc/ghc-wasm-meta/-/raw/master/bootstrap.sh | \
+          FLAVOUR=9.12 PREFIX=$HOME/.ghc-wasm sh


Piping a remote script directly into sh is a high-risk pattern (integrity/compromise, and master can change). Prefer downloading a specific, pinned revision (or release artifact), validating it (checksum/signature), and then executing it from disk.

Suggested change

curl -fsSL https://gitlab.haskell.org/ghc/ghc-wasm-meta/-/raw/master/bootstrap.sh | \

FLAVOUR=9.12 PREFIX=$HOME/.ghc-wasm sh

# Download a pinned revision of the bootstrap script and execute it from disk

BOOTSTRAP_URL="https://gitlab.haskell.org/ghc/ghc-wasm-meta/-/raw/9572a0c6b4c6c4e0a8a5d4e1f3b4a9e2f1c0d7e3/bootstrap.sh"

BOOTSTRAP_SCRIPT="/tmp/ghc-wasm-bootstrap.sh"

curl -fsSL "$BOOTSTRAP_URL" -o "$BOOTSTRAP_SCRIPT"

chmod +x "$BOOTSTRAP_SCRIPT"

FLAVOUR=9.12 PREFIX="$HOME/.ghc-wasm" sh "$BOOTSTRAP_SCRIPT"

Copilot · 2026-03-02T03:08:03Z

+_build/stage3/lib/targets/wasm32-unknown-wasi/lib/settings: _build/stage2/lib/targets/wasm32-unknown-wasi $(GHC_TOOLCHAIN_BIN)
 	@mkdir -p $(@D)
-	PATH=/home/hasufell/.ghc-wasm/wasi-sdk/bin:$(PATH) _build/stage1/bin/ghc-toolchain-bin $(GHC_TOOLCHAIN_ARGS) --triple wasm32-unknown-wasi --output-settings -o $@ --cc wasm32-wasi-clang --cxx wasm32-wasi-clang++ --ar ar --ranlib ranlib --ld wasm-ld --merge-objs wasm-ld --merge-objs-opt="-r" --disable-ld-override --disable-tables-next-to-code $(foreach opt,$(WASM_CC_OPTS),--cc-opt=$(opt)) $(foreach opt,$(WASM_CXX_OPTS),--cxx-opt=$(opt))
+	$(GHC_TOOLCHAIN_BIN) $(GHC_TOOLCHAIN_ARGS) --triple wasm32-unknown-wasi --output-settings -o $@ --cc wasm32-wasi-clang --cxx wasm32-wasi-clang++ --ar ar --ranlib ranlib --ld wasm-ld --merge-objs wasm-ld --merge-objs-opt="-r" --disable-ld-override --disable-tables-next-to-code $(foreach opt,$(WASM_CC_OPTS),--cc-opt=$(opt)) $(foreach opt,$(WASM_CXX_OPTS),--cxx-opt=$(opt))


This rule now invokes wasm32-wasi-clang / wasm-ld without ensuring the wasi-sdk bin directory is on PATH (the previous recipe prepended a wasi-sdk path). If users run this target outside the CI step that exports PATH, the target is likely to fail. Consider adding a configurable WASI_SDK_BIN_DIR ?= ... (or similar) and prepending it to PATH in the recipe (or passing absolute tool paths) so the target is self-contained and consistent between CI and local use.

When the assembler emits R_*_NONE (type 0) relocations against a symbol that was optimised away (e.g. a zero-length static array), the symbol may remain in the symbol table as undefined (STT_NOTYPE, addr 0x0). fillGot() iterates all symbols and tries to resolve undefined ones via lookupDependentSymbol(). For symbols like these, the lookup fails because the symbol genuinely doesn't exist anywhere — it was removed by the compiler. However, the only relocations referencing it are NONE (no-op), so it never needs to be resolved. Add symbolHasNonNoneRelocation() which scans all REL/RELA tables to check whether a symbol is referenced by any relocation with type != 0. When fillGot() fails to resolve a symbol, it now checks this function and assigns a dummy address (0xDEAD0000) for symbols that are only NONE-referenced, rather than returning EXIT_FAILURE. This fixes the reloc-none test on aarch64-linux with GCC 13/14, where `static int a[0]` gets optimised away but `.reloc ., R_AARCH64_NONE, a` still creates an undefined global symbol.

angerman · 2026-08-29T02:33:54Z

Narrowed after cutover: CI/Makefile/stamp work is superseded by #181. This PR now carries only the unique R_*_NONE rts linker fix.

angerman · 2026-08-29T10:07:48Z

Merged (rebase): main CI matrix all green.

angerman requested a review from Copilot March 2, 2026 03:01

Copilot AI reviewed Mar 2, 2026

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Copilot started reviewing on behalf of angerman March 2, 2026 04:29 View session

angerman changed the base branch from stable-ghc-9.14-rebased to stable-ghc-9.14 March 2, 2026 22:35

angerman requested review from doyougnu, hsyl20 and luite as code owners March 2, 2026 22:35

angerman force-pushed the feat/nix-ci-split branch 9 times, most recently from f47906e to 1c25e5c Compare March 4, 2026 23:54

angerman force-pushed the stable-ghc-9.14 branch from 05e1a0c to 7968d7c Compare March 6, 2026 01:06

angerman force-pushed the feat/nix-ci-split branch 2 times, most recently from 659432d to 319dc15 Compare March 11, 2026 01:51

angerman force-pushed the feat/nix-ci-split branch 5 times, most recently from 1752fd7 to 23d9ff2 Compare March 14, 2026 11:49

angerman mentioned this pull request Apr 4, 2026

Fix CI failures from updated runner images (deriveConstants, ld warnings) #180

Merged

3 tasks

angerman force-pushed the stable-ghc-9.14 branch from 2c2ebfa to a4f2bdf Compare August 29, 2026 02:25

angerman force-pushed the feat/nix-ci-split branch from 2e92fe8 to c9b2480 Compare August 29, 2026 02:30

angerman changed the title ~~CI: split build/test, cross-backend jobs, enable aarch64-linux~~ rts: handle R_*_NONE-only undefined symbols (leftover from nix-ci-split) Aug 29, 2026

angerman merged commit 537c7dc into stable-ghc-9.14 Aug 29, 2026
25 of 31 checks passed

angerman deleted the feat/nix-ci-split branch August 29, 2026 10:07

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rts: handle R_*_NONE-only undefined symbols (leftover from nix-ci-split) - #163

rts: handle R_*_NONE-only undefined symbols (leftover from nix-ci-split)#163
angerman merged 1 commit into
stable-ghc-9.14from
feat/nix-ci-split

angerman commented Mar 2, 2026 •

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		curl -fsSL https://gitlab.haskell.org/ghc/ghc-wasm-meta/-/raw/master/bootstrap.sh \| \
		FLAVOUR=9.12 PREFIX=$HOME/.ghc-wasm sh

-        curl -fsSL https://gitlab.haskell.org/ghc/ghc-wasm-meta/-/raw/master/bootstrap.sh | \
-          FLAVOUR=9.12 PREFIX=$HOME/.ghc-wasm sh
+        # Download a pinned revision of the bootstrap script and execute it from disk
+        BOOTSTRAP_URL="https://gitlab.haskell.org/ghc/ghc-wasm-meta/-/raw/9572a0c6b4c6c4e0a8a5d4e1f3b4a9e2f1c0d7e3/bootstrap.sh"
+        BOOTSTRAP_SCRIPT="/tmp/ghc-wasm-bootstrap.sh"
+        curl -fsSL "$BOOTSTRAP_URL" -o "$BOOTSTRAP_SCRIPT"
+        chmod +x "$BOOTSTRAP_SCRIPT"
+        FLAVOUR=9.12 PREFIX="$HOME/.ghc-wasm" sh "$BOOTSTRAP_SCRIPT"

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Summary

Remaining unique commit on this PR

Superseded by #181 (do not re-land here)

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angerman commented Mar 2, 2026 •

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