bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

And for patterns too

Browse source
This commit is contained in:
Michael Goulet 2022-07-21 01:26:00 +00:00
parent 99c32570bb
commit 8926dac549
5 changed files with 184 additions and 119 deletions
Download patch file Download diff file Expand all files Collapse all files

57
compiler/rustc_typeck/src/check/_match.rs
View file

@ -9,7 +9,6 @@ use rustc_span::Span;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_trait_selection::traits::{
IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
StatementAsExpression,
};
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
@ -75,8 +74,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
};
let mut other_arms = vec![]; // Used only for diagnostics.
let mut prior_arm_ty = None;
for (i, arm) in arms.iter().enumerate() {
let mut prior_arm = None;
for arm in arms {
if let Some(g) = &arm.guard {
self.diverges.set(Diverges::Maybe);
match g {
@ -96,21 +95,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let opt_suggest_box_span = self.opt_suggest_box_span(arm_ty, orig_expected);
let (arm_span, semi_span) =
self.get_appropriate_arm_semicolon_removal_span(&arms, i, prior_arm_ty, arm_ty);
let (span, code) = match i {
let (arm_block_id, arm_span) = if let hir::ExprKind::Block(blk, _) = arm.body.kind {
(Some(blk.hir_id), self.find_block_span(blk))
} else {
(None, arm.body.span)
};
let (span, code) = match prior_arm {
// The reason for the first arm to fail is not that the match arms diverge,
// but rather that there's a prior obligation that doesn't hold.
0 => (arm_span, ObligationCauseCode::BlockTailExpression(arm.body.hir_id)),
_ => (
None => (arm_span, ObligationCauseCode::BlockTailExpression(arm.body.hir_id)),
Some((prior_arm_block_id, prior_arm_ty, prior_arm_span)) => (
expr.span,
ObligationCauseCode::MatchExpressionArm(Box::new(MatchExpressionArmCause {
arm_block_id,
arm_span,
arm_ty,
prior_arm_block_id,
prior_arm_ty,
prior_arm_span,
scrut_span: scrut.span,
semi_span,
source: match_src,
prior_arms: other_arms.clone(),
last_ty: prior_arm_ty.unwrap(),
scrut_hir_id: scrut.hir_id,
opt_suggest_box_span,
})),
@ -139,7 +145,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let ret_ty = ret_coercion.borrow().expected_ty();
let ret_ty = self.inh.infcx.shallow_resolve(ret_ty);
self.can_coerce(arm_ty, ret_ty)
&& prior_arm_ty.map_or(true, |t| self.can_coerce(t, ret_ty))
&& prior_arm.map_or(true, |(_, t, _)| self.can_coerce(t, ret_ty))
// The match arms need to unify for the case of `impl Trait`.
&& !matches!(ret_ty.kind(), ty::Opaque(..))
}
@ -181,7 +187,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
if other_arms.len() > 5 {
other_arms.remove(0);
}
prior_arm_ty = Some(arm_ty);
prior_arm = Some((arm_block_id, arm_ty, arm_span));
}
// If all of the arms in the `match` diverge,
@ -207,32 +214,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
match_ty
}
fn get_appropriate_arm_semicolon_removal_span(
&self,
arms: &'tcx [hir::Arm<'tcx>],
i: usize,
prior_arm_ty: Option<Ty<'tcx>>,
arm_ty: Ty<'tcx>,
) -> (Span, Option<(Span, StatementAsExpression)>) {
let arm = &arms[i];
let (arm_span, mut semi_span) = if let hir::ExprKind::Block(blk, _) = &arm.body.kind {
(
self.find_block_span(blk),
prior_arm_ty
.and_then(|prior_arm_ty| self.could_remove_semicolon(blk, prior_arm_ty)),
)
} else {
(arm.body.span, None)
};
if semi_span.is_none() && i > 0 {
if let hir::ExprKind::Block(blk, _) = &arms[i - 1].body.kind {
let semi_span_prev = self.could_remove_semicolon(blk, arm_ty);
semi_span = semi_span_prev;
}
}
(arm_span, semi_span)
}
/// When the previously checked expression (the scrutinee) diverges,
/// warn the user about the match arms being unreachable.
fn warn_arms_when_scrutinee_diverges(&self, arms: &'tcx [hir::Arm<'tcx>]) {