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bors 8387095803 Auto merge of #152677 - ehuss:bootstrap-json-target-spec, r=davidtwco,jieyouxu
Support JSON target specs in bootstrap

JSON target specs were destabilized in https://github.com/rust-lang/rust/pull/150151 and https://github.com/rust-lang/rust/pull/151534. However, this broke trying to build rustc itself with a JSON target spec. This is because in a few places bootstrap is manually calling `rustc` without the ability for the user to provide additional flags (primarily, `-Zunstable-options` to enable JSON targets).

There's a few different ways to fix this. One would be to change these calls to `rustc` to include flags provided by the user (such as `RUSTFLAGS_NOT_BOOTSTRAP`). Just to keep things simple, this PR proposes to just unconditionally pass `-Zunstable-options`.

Another consideration here is how maintainable this is. A possible improvement here would be to have a function somewhere (BootstrapCommand, TargetSelection, free function) that would handle appropriately adding the `--target` flag. For example, that's what cargo does in [`CompileKind::add_target_arg`](592058c7ce/src/cargo/core/compiler/compile_kind.rs (L144-L154)).

I have only tested building the compiler and a few tools like rustdoc. I have not tested doing things like building other tools, running tests, etc.

This would be much easier if there was a Docker image for testing the use case of building rustc with a custom target spec (and even better if that ran in CI).

After the next beta branch, using target JSON specs will become more cumbersome because target specs with the `.json` extension will now require passing `-Zjson-target-spec` (from
https://github.com/rust-lang/cargo/pull/16557). This does not affect target specs without the `.json` extension (such as those from RUST_TARGET_PATH). From my testing, it should be sufficient to pass `CARGOFLAGS_NOT_BOOTSTRAP="-Zjson-target-spec"`. I think that should be fine, since this is not a particularly common use case AFAIK. We could extend bootstrap to auto-detect if the target is a file path, and pass `-Zjson-target-spec` appropriately. I tried something similar in f0bdd35483, which could be adapted if desired.

It would be nice if all of this is documented somewhere. https://rustc-dev-guide.rust-lang.org/building/new-target.html does not really say how to build the compiler with a custom json target.

Fixes https://github.com/rust-lang/rust/issues/151729
2026-02-17 17:35:50 +00:00
.github Add missing -Zjson-target-spec for m68k test 2026-02-13 08:13:29 -05:00
compiler Auto merge of #152755 - jdonszelmann:rollup-hcFNB2j, r=jdonszelmann 2026-02-17 13:26:15 +00:00
library Rollup merge of #152675 - folkertdev:va-list-docs, r=tgross35 2026-02-17 14:18:46 +01:00
LICENSES Synchronize Unicode license text from unicode.org 2024-11-20 00:54:12 -08:00
src Auto merge of #152677 - ehuss:bootstrap-json-target-spec, r=davidtwco,jieyouxu 2026-02-17 17:35:50 +00:00
tests Auto merge of #152755 - jdonszelmann:rollup-hcFNB2j, r=jdonszelmann 2026-02-17 13:26:15 +00:00
.clang-format Add .clang-format 2024-06-26 05:56:00 +08:00
.editorconfig editorconfig: don't use nonexistant syntax 2025-08-24 10:37:19 -05:00
.git-blame-ignore-revs git: ignore 60600a6fa4 for blame purposes 2025-04-17 11:50:24 +08:00
.gitattributes Mark .pp files as Rust 2025-03-29 12:39:06 +01:00
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bootstrap.example.toml Change how we build offload as a single Step 2025-12-22 23:50:11 +01:00
Cargo.lock Update sysinfo version to 0.38.2 2026-02-17 10:57:34 +01:00
Cargo.toml Switch to new_array_type_u64 2026-01-30 11:16:35 -05:00
CODE_OF_CONDUCT.md Remove the code of conduct; instead link https://www.rust-lang.org/conduct.html 2019-10-05 22:55:19 +02:00
configure Ensure ./configure works when configure.py path contains spaces 2024-02-16 18:57:22 +00:00
CONTRIBUTING.md Fix typos and grammar in top-level and src/doc documentation 2026-02-10 10:22:19 -05:00
COPYRIGHT dist: Re-work how we describe the licence of Rust in our distributions 2024-12-09 10:18:55 +00:00
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LICENSE-MIT dist: Re-work how we describe the licence of Rust in our distributions 2024-12-09 10:18:55 +00:00
package.json Update browser-ui-test version to 0.23.3 2026-01-27 21:14:25 +01:00
README.md Update Rust Foundation links in Readme 2025-03-16 19:03:40 -07:00
RELEASES.md Auto merge of #152506 - Urgau:rollup-MlGAszj, r=Urgau 2026-02-12 03:44:50 +00:00
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triagebot.toml Remove last remnants of rustc_query_system. 2026-02-16 22:56:47 +11:00
typos.toml Fix some typos of "similarity" 2026-01-29 23:40:37 +11:00
x Add uv to the list of possible python runners 2026-02-02 13:01:40 +01:00
x.ps1 use & instead of start-process in x.ps1 2023-12-09 09:46:16 -05:00
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yarn.lock Update npm package, remove another unused one, and fix some typing errors that started popping when we moved to yarn 2025-11-17 10:58:18 +02:00

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