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Rollup merge of #97971 - Soveu:varargs, r=jackh726

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Enable varargs support for calling conventions other than C or cdecl

This patch makes it possible to use varargs for calling conventions,
which are either based on C (efiapi) or C is based on them (sysv64 and win64).

Also pinging ``@phlopsi,`` because he noticed first this oversight when writing a library for UEFI.
This commit is contained in:
Michael Howell 2022-10-30 19:31:36 -07:00 • committed by GitHub
commit 9911229650
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12 changed files with 174 additions and 35 deletions
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48
compiler/rustc_hir_analysis/src/lib.rs
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@ -106,7 +106,7 @@ use rustc_middle::middle;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::util;
use rustc_session::config::EntryFnType;
use rustc_session::{config::EntryFnType, parse::feature_err};
use rustc_span::{symbol::sym, Span, DUMMY_SP};
use rustc_target::spec::abi::Abi;
use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
@ -118,20 +118,40 @@ use astconv::AstConv;
use bounds::Bounds;
fn require_c_abi_if_c_variadic(tcx: TyCtxt<'_>, decl: &hir::FnDecl<'_>, abi: Abi, span: Span) {
match (decl.c_variadic, abi) {
// The function has the correct calling convention, or isn't a "C-variadic" function.
(false, _) | (true, Abi::C { .. }) | (true, Abi::Cdecl { .. }) => {}
// The function is a "C-variadic" function with an incorrect calling convention.
(true, _) => {
let mut err = struct_span_err!(
tcx.sess,
span,
E0045,
"C-variadic function must have C or cdecl calling convention"
);
err.span_label(span, "C-variadics require C or cdecl calling convention").emit();
}
const ERROR_HEAD: &str = "C-variadic function must have a compatible calling convention";
const CONVENTIONS_UNSTABLE: &str = "`C`, `cdecl`, `win64`, `sysv64` or `efiapi`";
const CONVENTIONS_STABLE: &str = "`C` or `cdecl`";
const UNSTABLE_EXPLAIN: &str =
"using calling conventions other than `C` or `cdecl` for varargs functions is unstable";
if !decl.c_variadic || matches!(abi, Abi::C { .. } | Abi::Cdecl { .. }) {
return;
}
let extended_abi_support = tcx.features().extended_varargs_abi_support;
let conventions = match (extended_abi_support, abi.supports_varargs()) {
// User enabled additional ABI support for varargs and function ABI matches those ones.
(true, true) => return,
// Using this ABI would be ok, if the feature for additional ABI support was enabled.
// Return CONVENTIONS_STABLE, because we want the other error to look the same.
(false, true) => {
feature_err(
&tcx.sess.parse_sess,
sym::extended_varargs_abi_support,
span,
UNSTABLE_EXPLAIN,
)
.emit();
CONVENTIONS_STABLE
}
(false, false) => CONVENTIONS_STABLE,
(true, false) => CONVENTIONS_UNSTABLE,
};
let mut err = struct_span_err!(tcx.sess, span, E0045, "{}, like {}", ERROR_HEAD, conventions);
err.span_label(span, ERROR_HEAD).emit();
}
fn require_same_types<'tcx>(