Rollup merge of #68422 - Centril:diverges-simplify, r=eddyb
typeck: simplify the handling of `diverges`
Some drive-by cleanup while working on `hir::ExprKind::Let`.
Ostensibly, this has some perf benefits due to reduced allocation and whatnot as well.
r? @eddyb
diff --git a/src/librustc_typeck/check/_match.rs b/src/librustc_typeck/check/_match.rs
index bd84547..686cdfb 100644
--- a/src/librustc_typeck/check/_match.rs
+++ b/src/librustc_typeck/check/_match.rs
@@ -50,30 +50,13 @@
self.warn_arms_when_scrutinee_diverges(arms, match_src);
- // Otherwise, we have to union together the types that the
- // arms produce and so forth.
- let scrut_diverges = self.diverges.get();
- self.diverges.set(Diverges::Maybe);
+ // Otherwise, we have to union together the types that the arms produce and so forth.
+ let scrut_diverges = self.diverges.replace(Diverges::Maybe);
- // rust-lang/rust#55810: Typecheck patterns first (via eager
- // collection into `Vec`), so we get types for all bindings.
- let all_arm_pats_diverge: Vec<_> = arms
- .iter()
- .map(|arm| {
- let mut all_pats_diverge = Diverges::WarnedAlways;
- self.diverges.set(Diverges::Maybe);
- self.check_pat_top(&arm.pat, scrut_ty, Some(scrut.span), true);
- all_pats_diverge &= self.diverges.get();
-
- // As discussed with @eddyb, this is for disabling unreachable_code
- // warnings on patterns (they're now subsumed by unreachable_patterns
- // warnings).
- match all_pats_diverge {
- Diverges::Maybe => Diverges::Maybe,
- Diverges::Always { .. } | Diverges::WarnedAlways => Diverges::WarnedAlways,
- }
- })
- .collect();
+ // #55810: Type check patterns first so we get types for all bindings.
+ for arm in arms {
+ self.check_pat_top(&arm.pat, scrut_ty, Some(scrut.span), true);
+ }
// Now typecheck the blocks.
//
@@ -104,11 +87,11 @@
CoerceMany::with_coercion_sites(coerce_first, arms)
};
- let mut other_arms = vec![]; // used only for diagnostics
+ let mut other_arms = vec![]; // Used only for diagnostics.
let mut prior_arm_ty = None;
- for (i, (arm, pats_diverge)) in arms.iter().zip(all_arm_pats_diverge).enumerate() {
+ for (i, arm) in arms.iter().enumerate() {
if let Some(g) = &arm.guard {
- self.diverges.set(pats_diverge);
+ self.diverges.set(Diverges::Maybe);
match g {
hir::Guard::If(e) => {
self.check_expr_has_type_or_error(e, tcx.types.bool, |_| {})
@@ -116,7 +99,7 @@
};
}
- self.diverges.set(pats_diverge);
+ self.diverges.set(Diverges::Maybe);
let arm_ty = if source_if
&& if_no_else
&& i != 0
@@ -200,16 +183,14 @@
arms: &'tcx [hir::Arm<'tcx>],
source: hir::MatchSource,
) {
- if self.diverges.get().is_always() {
- use hir::MatchSource::*;
- let msg = match source {
- IfDesugar { .. } | IfLetDesugar { .. } => "block in `if` expression",
- WhileDesugar { .. } | WhileLetDesugar { .. } => "block in `while` expression",
- _ => "arm",
- };
- for arm in arms {
- self.warn_if_unreachable(arm.body.hir_id, arm.body.span, msg);
- }
+ use hir::MatchSource::*;
+ let msg = match source {
+ IfDesugar { .. } | IfLetDesugar { .. } => "block in `if` expression",
+ WhileDesugar { .. } | WhileLetDesugar { .. } => "block in `while` expression",
+ _ => "arm",
+ };
+ for arm in arms {
+ self.warn_if_unreachable(arm.body.hir_id, arm.body.span, msg);
}
}
diff --git a/src/librustc_typeck/check/expr.rs b/src/librustc_typeck/check/expr.rs
index 201a09f..b4c2b85 100644
--- a/src/librustc_typeck/check/expr.rs
+++ b/src/librustc_typeck/check/expr.rs
@@ -165,10 +165,8 @@
}
// Hide the outer diverging and has_errors flags.
- let old_diverges = self.diverges.get();
- let old_has_errors = self.has_errors.get();
- self.diverges.set(Diverges::Maybe);
- self.has_errors.set(false);
+ let old_diverges = self.diverges.replace(Diverges::Maybe);
+ let old_has_errors = self.has_errors.replace(false);
let ty = self.check_expr_kind(expr, expected, needs);
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 3818750..2dc198b 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4429,10 +4429,8 @@
self.warn_if_unreachable(stmt.hir_id, stmt.span, "statement");
// Hide the outer diverging and `has_errors` flags.
- let old_diverges = self.diverges.get();
- let old_has_errors = self.has_errors.get();
- self.diverges.set(Diverges::Maybe);
- self.has_errors.set(false);
+ let old_diverges = self.diverges.replace(Diverges::Maybe);
+ let old_has_errors = self.has_errors.replace(false);
match stmt.kind {
hir::StmtKind::Local(ref l) => {
@@ -4442,7 +4440,6 @@
hir::StmtKind::Item(_) => {}
hir::StmtKind::Expr(ref expr) => {
// Check with expected type of `()`.
-
self.check_expr_has_type_or_error(&expr, self.tcx.mk_unit(), |err| {
self.suggest_semicolon_at_end(expr.span, err);
});
