rust/compiler/rustc_passes/src
bors ed43cbcb88 Auto merge of #134299 - RalfJung:remove-start, r=compiler-errors
remove support for the (unstable) #[start] attribute

As explained by `@Noratrieb:`
`#[start]` should be deleted. It's nothing but an accidentally leaked implementation detail that's a not very useful mix between "portable" entrypoint logic and bad abstraction.

I think the way the stable user-facing entrypoint should work (and works today on stable) is pretty simple:
- `std`-using cross-platform programs should use `fn main()`. the compiler, together with `std`, will then ensure that code ends up at `main` (by having a platform-specific entrypoint that gets directed through `lang_start` in `std` to `main` - but that's just an implementation detail)
- `no_std` platform-specific programs should use `#![no_main]` and define their own platform-specific entrypoint symbol with `#[no_mangle]`, like `main`, `_start`, `WinMain` or `my_embedded_platform_wants_to_start_here`. most of them only support a single platform anyways, and need cfg for the different platform's ways of passing arguments or other things *anyways*

`#[start]` is in a super weird position of being neither of those two. It tries to pretend that it's cross-platform, but its signature is  a total lie. Those arguments are just stubbed out to zero on ~~Windows~~ wasm, for example. It also only handles the platform-specific entrypoints for a few platforms that are supported by `std`, like Windows or Unix-likes. `my_embedded_platform_wants_to_start_here` can't use it, and neither could a libc-less Linux program.
So we have an attribute that only works in some cases anyways, that has a signature that's a total lie (and a signature that, as I might want to add, has changed recently, and that I definitely would not be comfortable giving *any* stability guarantees on), and where there's a pretty easy way to get things working without it in the first place.

Note that this feature has **not** been RFCed in the first place.

*This comment was posted [in May](https://github.com/rust-lang/rust/issues/29633#issuecomment-2088596042) and so far nobody spoke up in that issue with a usecase that would require keeping the attribute.*

Closes https://github.com/rust-lang/rust/issues/29633

try-job: x86_64-gnu-nopt
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: test-various
2025-01-21 19:46:20 +00:00
..
liveness Reformat use declarations. 2024-07-29 08:26:52 +10:00
abi_test.rs Re-export more rustc_span::symbol things from rustc_span. 2024-12-18 13:38:53 +11:00
check_attr.rs remove support for the #[start] attribute 2025-01-21 06:59:15 -07:00
dead.rs Run clippy --fix for unnecessary_map_or lint 2025-01-19 19:15:00 +00:00
debugger_visualizer.rs Use SourceMap to load debugger visualizer files 2024-12-08 18:57:04 +00:00
diagnostic_items.rs Add tcx.visible_traits() and use it for producing diagnostics 2025-01-14 08:51:19 +00:00
entry.rs remove support for the #[start] attribute 2025-01-21 06:59:15 -07:00
errors.rs remove support for the #[start] attribute 2025-01-21 06:59:15 -07:00
hir_id_validator.rs Reformat using the new identifier sorting from rustfmt 2024-09-22 19:11:29 -04:00
input_stats.rs Rename PatKind::Lit to Expr 2025-01-08 07:34:59 +00:00
lang_items.rs Re-export more rustc_span::symbol things from rustc_span. 2024-12-18 13:38:53 +11:00
layout_test.rs Re-export more rustc_span::symbol things from rustc_span. 2024-12-18 13:38:53 +11:00
lib_features.rs Re-export more rustc_span::symbol things from rustc_span. 2024-12-18 13:38:53 +11:00
lib.rs Get rid of HIR const checker 2024-11-22 02:32:26 +00:00
liveness.rs On unused assign lint, detect mut arg: &Ty meant to be arg: &mut Ty 2025-01-11 01:34:23 +00:00
loops.rs Reformat using the new identifier sorting from rustfmt 2024-09-22 19:11:29 -04:00
naked_functions.rs turn hir::ItemKind::Fn into a named-field variant 2025-01-04 11:35:31 +01:00
reachable.rs turn hir::ItemKind::Fn into a named-field variant 2025-01-04 11:35:31 +01:00
stability.rs Rollup merge of #135003 - RalfJung:deprecate-allowed-through-unstable, r=davidtwco 2025-01-15 16:30:11 +01:00
upvars.rs Add warn(unreachable_pub) to rustc_passes. 2024-08-29 20:18:40 +10:00
weak_lang_items.rs Add support for wasm exception handling to Emscripten target 2025-01-06 10:29:54 +01:00