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Auto merge of #84401 - crlf0710:impl_main_by_path, r=petrochenkov

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Implement RFC 1260 with feature_name `imported_main`.

This is the second extraction part of #84062 plus additional adjustments.
This (mostly) implements RFC 1260.

However there's still one test case failure in the extern crate case. Maybe `LocalDefId` doesn't work here? I'm not sure.

cc https://github.com/rust-lang/rust/issues/28937
r? `@petrochenkov`
This commit is contained in:
bors 2021-04-30 06:59:37 +00:00
commit bcd696d722
38 changed files with 463 additions and 193 deletions
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27
compiler/rustc_codegen_ssa/src/base.rs
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@ -15,7 +15,7 @@ use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::profiling::{get_resident_set_size, print_time_passes_entry};
use rustc_data_structures::sync::{par_iter, ParallelIterator};
use rustc_hir as hir;
use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
use rustc_hir::def_id::{DefId, LOCAL_CRATE};
use rustc_hir::lang_items::LangItem;
use rustc_index::vec::Idx;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
@ -348,12 +348,29 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
cx: &'a Bx::CodegenCx,
) -> Option<Bx::Function> {
let main_def_id = cx.tcx().entry_fn(LOCAL_CRATE).map(|(def_id, _)| def_id)?;
let instance = Instance::mono(cx.tcx(), main_def_id.to_def_id());
let main_is_local = main_def_id.is_local();
let instance = Instance::mono(cx.tcx(), main_def_id);
if !cx.codegen_unit().contains_item(&MonoItem::Fn(instance)) {
if main_is_local {
// We want to create the wrapper in the same codegen unit as Rust's main
// function.
return None;
if !cx.codegen_unit().contains_item(&MonoItem::Fn(instance)) {
return None;
}
} else {
// FIXME: Add support for non-local main fn codegen
let span = cx.tcx().main_def.unwrap().span;
let n = 28937;
cx.sess()
.struct_span_err(span, "entry symbol `main` from foreign crate is not yet supported.")
.note(&format!(
"see issue #{} <https://github.com/rust-lang/rust/issues/{}> \
for more information",
n, n,
))
.emit();
cx.sess().abort_if_errors();
bug!();
}
let main_llfn = cx.get_fn_addr(instance);
@ -366,7 +383,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
fn create_entry_fn<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
cx: &'a Bx::CodegenCx,
rust_main: Bx::Value,
rust_main_def_id: LocalDefId,
rust_main_def_id: DefId,
use_start_lang_item: bool,
) -> Bx::Function {
// The entry function is either `int main(void)` or `int main(int argc, char **argv)`,