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Auto merge of #96892 - oli-obk:🐌_obligation_cause_code_🐌, r=estebank

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Clean up derived obligation creation

r? `@estebank`

working on fixing the perf regression from https://github.com/rust-lang/rust/pull/91030#issuecomment-1083360210
This commit is contained in:
bors 2022-05-17 01:46:25 +00:00
commit c1d65eaa45
11 changed files with 176 additions and 219 deletions
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30
compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
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@ -12,7 +12,6 @@ use crate::check::{
use crate::structured_errors::StructuredDiagnostic;
use rustc_ast as ast;
use rustc_data_structures::sync::Lrc;
use rustc_errors::{Applicability, Diagnostic, DiagnosticId, MultiSpan};
use rustc_hir as hir;
use rustc_hir::def::{CtorOf, DefKind, Res};
@ -1596,24 +1595,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// Peel derived obligation, because it's the type that originally
// started this inference chain that matters, not the one we wound
// up with at the end.
fn unpeel_to_top(
mut code: Lrc<ObligationCauseCode<'_>>,
) -> Lrc<ObligationCauseCode<'_>> {
let mut result_code = code.clone();
fn unpeel_to_top<'a, 'tcx>(
mut code: &'a ObligationCauseCode<'tcx>,
) -> &'a ObligationCauseCode<'tcx> {
let mut result_code = code;
loop {
let parent = match &*code {
ObligationCauseCode::ImplDerivedObligation(c) => {
c.derived.parent_code.clone()
}
let parent = match code {
ObligationCauseCode::ImplDerivedObligation(c) => &c.derived.parent_code,
ObligationCauseCode::BuiltinDerivedObligation(c)
| ObligationCauseCode::DerivedObligation(c) => c.parent_code.clone(),
_ => break,
| ObligationCauseCode::DerivedObligation(c) => &c.parent_code,
_ => break result_code,
};
result_code = std::mem::replace(&mut code, parent);
(result_code, code) = (code, parent);
}
result_code
}
let self_: ty::subst::GenericArg<'_> = match &*unpeel_to_top(error.obligation.cause.clone_code()) {
let self_: ty::subst::GenericArg<'_> = match unpeel_to_top(error.obligation.cause.code()) {
ObligationCauseCode::BuiltinDerivedObligation(code) |
ObligationCauseCode::DerivedObligation(code) => {
code.parent_trait_pred.self_ty().skip_binder().into()
@ -1663,13 +1659,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// We make sure that only *one* argument matches the obligation failure
// and we assign the obligation's span to its expression's.
error.obligation.cause.span = args[ref_in].span;
let parent_code = error.obligation.cause.clone_code();
*error.obligation.cause.make_mut_code() =
error.obligation.cause.map_code(|parent_code| {
ObligationCauseCode::FunctionArgumentObligation {
arg_hir_id: args[ref_in].hir_id,
call_hir_id: expr.hir_id,
parent_code,
};
}
});
} else if error.obligation.cause.span == call_sp {
// Make function calls point at the callee, not the whole thing.
if let hir::ExprKind::Call(callee, _) = expr.kind {