selfhost-verify: artefactos del frente rust (parche run_rustc + runners stage0-musl)
Rastrea las correcciones del frente rust que vivían en .scratch/ (gitignored): - run_rustc.patch (vs mrustc be69c74): minicargo/hello con --target musl; RUSTFLAGS + sitios de link con link-self-contained=no (CRT vía gcc Alpine, link dinámico contra musl); proxy host-units con crt-static off (sin inject de --target, host==target==musl con el stage0 musl-host). - build-stage0-musl.sh: rebuild del stage0 rustc+cargo con host triple musl (CFG_COMPILER_HOST_TRIPLE vía RUSTC_TARGET, --target vía MRUSTC_TARGET), reusa LLVM + bin/mrustc. Gotcha OUTDIR_SUF documentado. - run-runrustc.sh: corre targets de run_rustc en el sandbox devfs apuntando al stage0 musl-host. - README: diagnóstico de los 3 snags acoplados (std-gnu mmap64/open64, CRT self-contained ausente, host-triple gnu + proc-macros) y el workflow. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Claude Opus 4.8
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# rust-frontier — self-hosting the builder's rust toolchain
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The last frontier of `selfhost-verify` variante (b): replace the Alpine
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`rustc/cargo 1.91.1` in `/toolchain` with a hammer-built rust, via the **purist
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mrustc chain** (no prebuilt rustc binary). Path:
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mrustc → rustc 1.90.0 (builds bundled LLVM) → 1.91.0 → 1.91.1
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These scripts + patch are the working artifacts. The mrustc tree itself lives in
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`.scratch/mrustc` (gitignored — it's a large third-party clone, upstream master
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`be69c74`); only our deltas are tracked here.
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## Files
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- **`run_rustc.patch`** — patch against mrustc `be69c74` for `run_rustc/Makefile`
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and `run_rustc/rustc_proxy.sh`. Apply from the mrustc root:
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`git -C .scratch/mrustc apply /path/to/run_rustc.patch`
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- **`build-stage0-musl.sh`** — rebuild the mrustc stage0 `rustc`+`cargo` with a
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**musl host triple** (`output-1.90.0-x86_64-unknown-linux-musl/`). Run inside
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the Alpine devfs sandbox (gcc, MRUSTC_TARGET_VER=1.90). Reuses the already-built
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LLVM and `bin/mrustc`.
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- **`run-runrustc.sh`** — run a `run_rustc` make target inside the devfs sandbox,
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pointed at the musl-host stage0.
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> Both runners hardcode `/home/sergio/hammer` and assume the prepared devfs at
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> `.dev-fs/alpine` (256-TLS-key musl loader + g++; see the bootstrap-devfs notes).
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## Why the patches exist (the snags)
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The lab is **musl-only** (Alpine devfs); the 4/4 inputs (arje-zero/hammerd) are
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built `--target x86_64-unknown-linux-musl`. Three coupled problems had to be fixed
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to bootstrap a usable rust there:
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1. **stage-1 std built for gnu** (`mmap64`/`open64` undefined at link).
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`minicargo` was invoked without `--target`, so it used mrustc's default **gnu**
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triple — and gnu std references glibc's LFS64 symbols that musl 1.2.5 doesn't
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export. Fix: pass `--target $(RUSTC_TARGET)` to minicargo (Makefile:162) and to
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the stage-1 smoke-test (Makefile:172). A correct musl std uses the **base** libc
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symbols (`open`/`mmap`/…), matching Alpine's reference std.
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2. **self-contained CRT absent.** musl's default link is `-static-pie` against a
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`lib/rustlib/<t>/lib/self-contained/` CRT dir that the mrustc sysroot never
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populates. Fix: `-C target-feature=-crt-static -C link-self-contained=no` so the
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Alpine gcc supplies crt1/crti/crtn + crtbeginS/crtendS and links dynamically
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against the system musl (RUSTFLAGS in Makefile:111, plus the per-link sites).
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3. **host-triple = gnu on a musl system** (the deep one). cargo compiles
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build-scripts and **proc-macros** for the *host*; mrustc's stage0 rustc has its
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host triple baked as `x86_64-unknown-linux-gnu` (not runtime-overridable). A
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proxy `--target musl` inject fixes build-script *bins*, but **proc-macros are
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dlopen'd and must match the host triple structurally** — injection makes them
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target artifacts that rustc rejects. Aliasing musl rlibs as gnu also fails:
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rustc reads the triple from rlib *metadata* (`E0461`), not the path.
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**The only fix is a stage0 rustc whose host triple is musl** — that's what
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`build-stage0-musl.sh` produces (`CFG_COMPILER_HOST_TRIPLE` via `RUSTC_TARGET`,
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`--target` via `MRUSTC_TARGET`). Then host==target==musl: cargo doesn't
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cross-compile, proc-macros load natively, and `rustc_proxy.sh` only needs the
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CRT flags (no `--target` inject).
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Gotcha: do **not** pass `OUTDIR_SUF` on make's command line — a command-line var
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can't be reassigned by the makefile, so the `-musl` suffix append is skipped and
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the build contaminates the gnu output dir. Let it default.
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## Workflow
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```sh
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# 1. apply the run_rustc patch into the mrustc clone
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git -C .scratch/mrustc apply scripts/rust-frontier/run_rustc.patch
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# 2. rebuild stage0 rustc+cargo with a musl host triple (~hours, reuses LLVM)
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.scratch/build-stage0-musl.sh # -> output-1.90.0-x86_64-unknown-linux-musl/
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# 3. build the optimised rustc + cargo via run_rustc (stage 1/2/3)
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.scratch/run-runrustc.sh all
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# 4. (next) climb 1.90.0 → 1.91.0 → 1.91.1, then swap rust into /toolchain
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```
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Full diagnostic history is in the `selfhost-verify-rust-frontier` memory.
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Executable
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#!/bin/sh
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# Path A: rebuild the mrustc stage0 rustc+cargo with a MUSL host triple, so
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# CFG_COMPILER_HOST_TRIPLE=x86_64-unknown-linux-musl is baked in. This lets
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# run_rustc's cargo build proc-macros/build-scripts natively (host==target==musl)
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# without the proxy --target hack. LLVM + mrustc are reused (already built).
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# Output lands in output-1.90.0-x86_64-unknown-linux-musl/.
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set -eu
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ROOT=/home/sergio/hammer
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DEVFS=$ROOT/.dev-fs/alpine
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MRUSTC=$ROOT/.scratch/mrustc
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T=x86_64-unknown-linux-musl
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run() {
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bwrap \
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--bind "$DEVFS" / \
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--bind "$MRUSTC" /mrustc \
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--dev /dev --proc /proc \
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--tmpfs /tmp --tmpfs /run \
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--setenv PATH /usr/bin:/bin:/usr/sbin:/sbin \
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--setenv HOME /root --setenv TMPDIR /tmp \
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--setenv MRUSTC_TARGET_VER 1.90 \
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--setenv CC gcc --setenv CXX g++ \
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--chdir /mrustc \
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make -f minicargo.mk \
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RUSTC_VERSION=1.90.0 \
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MRUSTC_TARGET=$T RUSTC_TARGET=$T \
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RUSTC_INSTALL_BINDIR=bin PARLEVEL=8 \
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"$@"
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}
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echo "=== [1/3] LIBS (musl bootstrap std) ==="
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run LIBS
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echo "=== [2/3] rustc (musl host) ==="
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run output-1.90.0-$T/rustc
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echo "=== [3/3] cargo (musl host) ==="
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LIBGIT2_SYS_USE_PKG_CONFIG=1 run output-1.90.0-$T/cargo
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echo "=== DONE ==="
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ls -la output-1.90.0-$T/rustc output-1.90.0-$T/cargo
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Executable
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#!/bin/sh
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# Run a run_rustc make target inside the Alpine devfs sandbox (musl, 256-TLS loader, gcc).
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# Usage: run-runrustc.sh <make-target> [extra make args...]
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set -eu
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ROOT=/home/sergio/hammer
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DEVFS=$ROOT/.dev-fs/alpine
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MRUSTC=$ROOT/.scratch/mrustc
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TARGET=${1:?make target required}
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shift || true
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exec bwrap \
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--bind "$DEVFS" / \
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--bind "$MRUSTC" /mrustc \
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--dev /dev --proc /proc \
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--tmpfs /tmp --tmpfs /run \
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--setenv PATH /usr/bin:/bin:/usr/sbin:/sbin \
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--setenv HOME /root \
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--setenv TMPDIR /tmp \
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--setenv MRUSTC_TARGET_VER 1.90 \
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--setenv CC gcc --setenv CXX g++ \
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--chdir /mrustc/run_rustc \
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make RUSTC_VERSION=1.90.0 OUTDIR_SUF=-1.90.0-x86_64-unknown-linux-musl \
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RUSTC_TARGET=x86_64-unknown-linux-musl PARLEVEL=8 \
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"$TARGET" "$@"
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diff --git a/run_rustc/Makefile b/run_rustc/Makefile
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index e78d8c5..4d6ef5d 100644
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--- a/run_rustc/Makefile
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+++ b/run_rustc/Makefile
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@@ -108,7 +108,7 @@ CARGO_FLAGS := --target $(RUSTC_TARGET) -j $(PARLEVEL) --release --verbose
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CARGO_ENV := CFG_COMPILER_HOST_TRIPLE=$(RUSTC_TARGET)
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CARGO_ENV += RUSTC_BOOTSTRAP=1
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CARGO_ENV += CARGO_HOME=$(CARGO_HOME)
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-CARGO_ENV += RUSTFLAGS="-Z force-unstable-if-unmarked -C link_args=-Wl,-rpath,\$$ORIGIN/../lib -C target-feature=-crt-static"
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+CARGO_ENV += RUSTFLAGS="-Z force-unstable-if-unmarked -C link_args=-Wl,-rpath,\$$ORIGIN/../lib -C target-feature=-crt-static -C link-self-contained=no"
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fn_opt_copy = (test -e "$2" && test ! "$1" -nt "$2") || cp "$1" "$2"
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@@ -159,7 +159,7 @@ $(LIBDIR_S)libstd.rlib: $(BINDIR_S)rustc $(MINICARGO) Makefile
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@echo "[MINICARGO] $(RUST_SRC_LIBS)std > $(LIBDIR_S)"
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mkdir -p $(LIBDIR_S)
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ifneq ($(TARGETVER_LEAST_1_74),)
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- $V+STD_ENV_ARCH=$(RUSTC_ARCH) MRUSTC_PATH=$(abspath $(BINDIR_S)rustc) $(MINICARGO) --vendor-dir $(VENDOR_DIR) --script-overrides ../script-overrides/stable-$(RUSTC_VERSION)-$(PLATFORM)/ --output-dir $(LIBDIR_S) $(RUST_SRC_LIBS)sysroot
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+ $V+STD_ENV_ARCH=$(RUSTC_ARCH) MRUSTC_PATH=$(abspath $(BINDIR_S)rustc) $(MINICARGO) --vendor-dir $(VENDOR_DIR) --script-overrides ../script-overrides/stable-$(RUSTC_VERSION)-$(PLATFORM)/ --output-dir $(LIBDIR_S) --target $(RUSTC_TARGET) $(RUST_SRC_LIBS)sysroot
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else
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$V+MRUSTC_PATH=$(abspath $(BINDIR_S)rustc) $(MINICARGO) --vendor-dir $(VENDOR_DIR) --script-overrides ../script-overrides/stable-$(RUSTC_VERSION)-$(PLATFORM)/ --output-dir $(LIBDIR_S) $(RUST_SRC_LIBS)std
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$V+MRUSTC_PATH=$(abspath $(BINDIR_S)rustc) $(MINICARGO) --vendor-dir $(VENDOR_DIR) --script-overrides ../script-overrides/stable-$(RUSTC_VERSION)-$(PLATFORM)/ --output-dir $(LIBDIR_S) $(RUST_SRC_LIBS)panic_unwind
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@@ -169,7 +169,7 @@ endif
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# Build hello_world using the bootstrapping compiler (mrustc-built rustc)
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$(BINDIR_S)hello_world: $(RUST_SRC_HELLO) $(LIBDIR_S)libstd.rlib $(BINDIR_S)rustc
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@mkdir -p $(dir $@)
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- $V$(BINDIR_S)rustc $(RUSTFLAGS_$@) -L $(LIBDIR_S) $< -o $@
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+ $V$(BINDIR_S)rustc $(RUSTFLAGS_$@) --target $(RUSTC_TARGET) -C target-feature=-crt-static -C link-self-contained=no -L $(LIBDIR_S) $< -o $@
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# ---
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# Stage 2: Build a proper libstd (which includes dynamc libraries too)
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diff --git a/run_rustc/rustc_proxy.sh b/run_rustc/rustc_proxy.sh
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index 3f4f2b9..78f6f1d 100755
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--- a/run_rustc/rustc_proxy.sh
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+++ b/run_rustc/rustc_proxy.sh
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@@ -17,7 +17,12 @@ if is_target "$@"; then
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#echo " [REAL]" "$@" >&2
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${PROXY_RUSTC} "$@"
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else
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+ # Host (build-script / proc-macro) build. With the musl-host stage0 rustc its
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+ # default target IS x86_64-unknown-linux-musl, so no --target inject is needed
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+ # (host==target==musl, proc-macros load natively). Just force dynamic +
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+ # non-self-contained so the Alpine gcc supplies the CRT (the mrustc sysroot has
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+ # no self-contained CRT dir, and musl's default is static-pie).
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#echo " [BOOTSTRAP]" "$@" >&2
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- ${PROXY_MRUSTC} "$@"
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+ ${PROXY_MRUSTC} -C target-feature=-crt-static -C link-self-contained=no "$@"
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fi
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