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Sunrisepeak merged 4 commits into from
Aug 24, 2026
Merged

declare the compiler runtime, which was always the larger half of this package #4

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81497c6
declare the compiler runtime, which was always the larger half of thi…
Sunrisepeak Aug 24, 2026
e772356
ci: drop the branch-built tool, and make the bare-metal step reach ba…
Sunrisepeak Aug 24, 2026
747085e
ci: pin 2026.8.24.4, which is the release that survives the bare-meta…
Sunrisepeak Aug 24, 2026
3e68059
ci: the emulated serial console ends lines with CRLF
Sunrisepeak Aug 24, 2026
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101 changes: 23 additions & 78 deletions .github/workflows/ci.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ on:
workflow_dispatch:

env:
MCPP_VERSION: 2026.8.19.4
MCPP_VERSION: 2026.8.24.4
XLINGS_VERSION: v2026.8.17.2
XLINGS_NON_INTERACTIVE: '1'

Expand Down Expand Up @@ -107,61 +107,6 @@ jobs:
xlings install xim:qemu-riscv -y
XLINGS_HOME="$HOME/.mcpp/registry" xlings install xim:qemu-riscv -y

# ⚠️ THE BUILD TOOL IS BUILT FROM A BRANCH, AND THAT IS TEMPORARY.
#
# This step needs four decisions that no released mcpp makes yet, each of
# which belongs to the tool rather than to this package:
#
# `import std` is gated on whether a package PROVIDES a standard
# library for the target rather than on whether the target is
# freestanding; a package may carry its own std module source;
# `-fno-exceptions` / `-fno-rtti` / `-ffreestanding` come off when the
# graph supplies a C++ runtime built for the target; and unwind tables
# go on, because the compiler turns them off for this kind of target
# and a partial set of tables stops the walk rather than degrading it.
#
# They are on mcpp-community/mcpp#486. Until that is released this job
# builds the tool the same way every other dependency here is taken —
# from the branch — so the criterion below is actually enforced instead
# of being a comment saying it was verified once on a laptop.
#
# ⇒ When #486 ships, delete this step and raise MCPP_VERSION.
- name: The build tool, from the branch that has what this needs
if: matrix.toolchain == 'llvm@22.1.8'
run: |
set -euo pipefail
git clone --depth 1 -b feat/import-std-capability \
https://github.com/mcpp-community/mcpp "$RUNNER_TEMP/mcpp-src"
cd "$RUNNER_TEMP/mcpp-src"
# ⚠️ THE CLONE CARRIES A WORKSPACE PIN, AND IT NAMES A VERSION THE
# INDEX NO LONGER HAS.
#
# xlings: version '2026.8.17.1' not found for 'mcpp'
# available: 2026.8.19.4
#
# `.xlings.json` at a repository root says which mcpp a build in that
# tree uses, and mcpp's own bootstrap pin does not move when mcpp is
# released — it is the version that was current when the pin was last
# touched. Cloning the branch therefore imports a pin that is only
# valid inside that repository's own CI, where the same file selects
# what gets installed.
#
# Rewriting it to the version this job already installed is what makes
# the two agree. It changes nothing about what is being tested: the
# pin selects the tool that BUILDS mcpp, and what is under test is the
# mcpp that comes out.
printf '{\n "workspace": {\n "mcpp": "%s"\n }\n}\n' "$MCPP_VERSION" > .xlings.json
# ⚠️ `--dev` AND NOT `--release`. What is under test is a set of
# decisions the tool makes about compile flags; an optimisation level
# changes none of them. Measured: the release self-build took over
# half an hour of a sixty-minute job on a two-core runner, which is
# most of the budget spent on something the test does not observe.
mcpp build --dev
BUILT=$(find target -type f -name mcpp -perm -u+x | head -1)
[ -n "$BUILT" ] || { echo "::error::mcpp did not build"; exit 1; }
echo "$(cd "$(dirname "$BUILT")" && pwd)" >> "$GITHUB_PATH"
"$BUILT" --version

- name: The same source on bare metal, with exceptions
if: matrix.toolchain == 'llvm@22.1.8'
run: |
Expand All @@ -175,7 +120,18 @@ jobs:
grep -q '"qemu-system-riscv64"' mcpp.toml \
|| { echo "::error::the manifest no longer carries the bare emulator name"; exit 1; }
sed -i "s|\"qemu-system-riscv64\"|\"$Q\"|" mcpp.toml
mcpp run 2>&1 | tee out.log
# ⚠️ `--target riscv64-none-elf`, AND THE FLAG IS THE WHOLE STEP.
#
# This manifest carries no `[build] target`, so a bare `mcpp run`
# builds for the HOST and passes — the four lines below appear either
# way, which is the manifest's own claim and not an accident. A step
# named "on bare metal" that omits the flag therefore reports green
# over a host build and has never once reached OpenSBI. Measured
# 2026-08-24: the artefact was `target/x86_64-linux-gnu/…`.
mcpp run --target riscv64-none-elf 2>&1 | tee out.log
# The emulator's own banner, so a run that never left the host cannot
# satisfy this step by printing the four application lines.
grep -q 'Boot HART' out.log # firmware ran; this is OpenSBI
grep -q 'sorted: 2 4 7' out.log # containers + algorithms + the allocator
grep -q 'caught: 42' out.log # the unwinder found the handler
grep -q 'unwound: true' out.log # ⭐ and ran a destructor on the way
Expand All @@ -195,8 +151,16 @@ jobs:
cd examples/same-source && mcpp run 2>&1 | tee host.log
grep -q 'import std over openkal: ok' host.log
# The four lines are the same four lines.
diff <(grep -E '^(sorted|caught|unwound|import std over openkal):' out.log) \
<(grep -E '^(sorted|caught|unwound|import std over openkal):' host.log)
#
# ⚠️ `tr -d '\r'` ON BOTH SIDES, AND IT IS NOT COSMETIC. The bare-metal
# run reaches the console through an emulated 16550 UART, and a serial
# console terminates lines with CRLF; the native run does not. Without
# this the diff reports four differing lines whose visible text is
# identical, which reads as a failure of the claim being tested rather
# than of the transport carrying it. The assertion is about what the
# program printed, not about how the bytes arrived.
diff <(grep -E '^(sorted|caught|unwound|import std over openkal):' out.log | tr -d '\r') \
<(grep -E '^(sorted|caught|unwound|import std over openkal):' host.log | tr -d '\r')

# ⭐⭐ AND THE SAME SOURCE FOR TWO MACHINES THIS ONE IS NOT.
#
Expand Down Expand Up @@ -398,25 +362,6 @@ jobs:
mcpp toolchain install llvm 22.1.8
mcpp toolchain default 'llvm@22.1.8'

# ⚠️ Same temporary step as the Linux job: the decisions this exercises are
# on mcpp#486 and not in any release. When that ships, this goes and
# MCPP_VERSION rises. See the long note in the `runtime` job.
- name: The build tool, from the branch that has what this needs
run: |
set -euo pipefail
git clone --depth 1 -b feat/import-std-capability \
https://github.com/mcpp-community/mcpp "$RUNNER_TEMP/mcpp-src"
cd "$RUNNER_TEMP/mcpp-src"
printf '{\n "workspace": {\n "mcpp": "%s"\n }\n}\n' "$MCPP_VERSION" > .xlings.json
mcpp build --dev
# ⚠️ Named exactly, and `-perm` is not used. On Windows every file
# reads as executable, so a permission test selects nothing useful;
# `mcpp.exe` is the name there and `mcpp` everywhere else.
BUILT=$(find target -type f \( -name 'mcpp' -o -name 'mcpp.exe' \) | head -1)
[ -n "$BUILT" ] || { echo "::error::mcpp did not build"; exit 1; }
echo "$(cd "$(dirname "$BUILT")" && pwd)" >> "$GITHUB_PATH"
"$BUILT" --version

- name: Every target, from this host
run: |
set -euo pipefail
Expand Down
72 changes: 40 additions & 32 deletions mcpp.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -18,39 +18,47 @@ repo = "https://github.com/mcpplibs/openkal-llvm-runtime"
# The older spelling is kept beside the current one so that an engine
# predating the layer vocabulary still recognises this package. Both name the
# same layer; a newer engine reads the second and ignores the first.
provides = ["hosted-standard-library", "mcpp:c++-abi=libc++"]
provides = [
"hosted-standard-library",
"mcpp:c++-abi=libc++",
# ⚠️ THE LARGER HALF OF THIS PACKAGE, AND IT IS NOT A C++ THING.
#
# Of the 729 objects built here, 498 are compiler-rt's builtins and 21 are
# libunwind's. Those are what a C PROGRAM needs — `__udivti3` and its
# relatives have nothing to do with C++ — so declaring them under the C++
# layer would say this package supplies something it does not and conceal
# something it does.
"mcpp:compiler-runtime=compiler-rt",
]

# ⚠️ THE COMPILER RUNTIME IS THE LARGER HALF OF THIS PACKAGE AND IS NOT YET
# DECLARED, BECAUSE DECLARING IT WOULD MAKE THIS MANIFEST UNREADABLE TO EVERY
# RELEASED BUILD TOOL.
#
# Measured: of the 729 objects built here, 498 are compiler-rt's builtins and 21
# are libunwind's. Those are what a C PROGRAM needs — `__udivti3` and its
# relatives have nothing to do with C++ — so declaring them under the C++ layer
# says this package supplies something it does not and conceals something it
# does.
#
# The layer is named `mcpp:compiler-runtime` from mcpp 2026.8.24.2, and a build
# tool released before that reports:
#
# error: `provides = ["mcpp:compiler-runtime=compiler-rt"]` names no
# capability mcpp knows.
#
# ⚠️ That refusal is itself fixed in 2026.8.24.2 — an unknown layer name in a
# DEPENDENCY's manifest is now ignored with a warning rather than refused — but
# the fix cannot apply retroactively to tools already released.
#
# ⚠️ AND THE CRITERION IS NOT THIS PACKAGE'S FLOOR. It is what the index serves,
# because that is what a reader of this file actually has. Measured 2026-08-24
# against the two keys, with a dependency declaring each and a build tool taken
# from the version the index named `latest`:
#
# requires = ["mcpp:compiler=llvm"] 2026.8.24.1 exit 0, ignored
# provides = ["mcpp:compiler-runtime=…"] 2026.8.24.1 exit 2, refused
#
# So `requires` is safe to publish today and the layer declaration is not. The
# gate on adding it is that the index's `latest` be at 2026.8.24.2 or above —
# not that a newer mcpp exists, and not that this package's floor was raised.
# ── The floor this declaration puts under the package ───────────────────────
#
# `mcpp:compiler-runtime` is a layer name mcpp learned in 2026.8.24.2. Measured
# 2026-08-24, one dependency declaring one key, each build tool taken from a
# published release:
#
# requires = ["mcpp:compiler=llvm"] 2026.8.19.4 exit 0 not validated
# 2026.8.24.1 exit 0 not validated
# provides = ["mcpp:compiler-runtime=…"] 2026.8.19.4 exit 0 not validated
# 2026.8.24.1 exit 2 REFUSED
# 2026.8.24.3 exit 0 resolved
#
# ⚠️ THE TWO ZEROES AT 2026.8.19.4 ARE NOT THE SAME KIND OF SUCCESS AS THE ONE
# AT 2026.8.24.3. That tool predates the layer vocabulary and ignores the whole
# array, so it neither refuses the declaration nor reads it. A CI pinned there
# would report green over a manifest whose central claim was never examined,
# which is why this package's `MCPP_VERSION` moves in the same change that adds
# the line. It moves to 2026.8.24.4 rather than .3: raising the pin made the
# bare-metal step below reach OpenSBI for the first time, and the step AFTER it
# then failed — `mcpp run --target X` had been recording X's build under the
# host's cache key, so the next bare `mcpp run` exec'd the cross artefact. The
# defect predates this package and was found only because a step that claimed to
# test bare metal started doing so. Fixed in mcpp-community/mcpp#498.
#
# The window that REFUSES is 2026.8.24.1 alone — between the release that began
# validating the `mcpp:` prefix and the one that learned this layer. Publishing
# into it was deferred until the index served a tool past it; the index reached
# 2026.8.24.3 on 2026-08-24 and these packages have no installed base behind it.

# What this package needs of the layer it does not supply.
#
Expand Down
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