diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 9bd5d1a2a97..b308a80f7ba 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -333,6 +333,15 @@ fn mir_promoted(
body.tainted_by_errors = Some(error_reported);
}
+ // Collect `required_consts` *before* promotion, so if there are any consts being promoted
+ // we still add them to the list in the outer MIR body.
+ let mut required_consts = Vec::new();
+ let mut required_consts_visitor = RequiredConstsVisitor::new(&mut required_consts);
+ for (bb, bb_data) in traversal::reverse_postorder(&body) {
+ required_consts_visitor.visit_basic_block_data(bb, bb_data);
+ }
+ body.required_consts = required_consts;
+
// What we need to run borrowck etc.
let promote_pass = promote_consts::PromoteTemps::default();
pm::run_passes(
@@ -342,14 +351,6 @@ fn mir_promoted(
Some(MirPhase::Analysis(AnalysisPhase::Initial)),
);
- // Promotion generates new consts; we run this after promotion to ensure they are accounted for.
- let mut required_consts = Vec::new();
- let mut required_consts_visitor = RequiredConstsVisitor::new(&mut required_consts);
- for (bb, bb_data) in traversal::reverse_postorder(&body) {
- required_consts_visitor.visit_basic_block_data(bb, bb_data);
- }
- body.required_consts = required_consts;
-
let promoted = promote_pass.promoted_fragments.into_inner();
(tcx.alloc_steal_mir(body), tcx.alloc_steal_promoted(promoted))
}
diff --git a/compiler/rustc_mir_transform/src/promote_consts.rs b/compiler/rustc_mir_transform/src/promote_consts.rs
index 03ca322e4db..928a23006fa 100644
--- a/compiler/rustc_mir_transform/src/promote_consts.rs
+++ b/compiler/rustc_mir_transform/src/promote_consts.rs
@@ -688,7 +688,6 @@ impl<'tcx> Validator<'_, 'tcx> {
}
}
-// FIXME(eddyb) remove the differences for promotability in `static`, `const`, `const fn`.
fn validate_candidates(
ccx: &ConstCx<'_, '_>,
temps: &mut IndexSlice<Local, TempState>,
@@ -713,6 +712,10 @@ struct Promoter<'a, 'tcx> {
/// If true, all nested temps are also kept in the
/// source MIR, not moved to the promoted MIR.
keep_original: bool,
+
+ /// If true, add the new const (the promoted) to the required_consts of the parent MIR.
+ /// This is initially false and then set by the visitor when it encounters a `Call` terminator.
+ add_to_required: bool,
}
impl<'a, 'tcx> Promoter<'a, 'tcx> {
@@ -815,6 +818,10 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
TerminatorKind::Call {
mut func, mut args, call_source: desugar, fn_span, ..
} => {
+ // This promoted involves a function call, so it may fail to evaluate.
+ // Let's make sure it is added to `required_consts` so that that failure cannot get lost.
+ self.add_to_required = true;
+
self.visit_operand(&mut func, loc);
for arg in &mut args {
self.visit_operand(&mut arg.node, loc);
@@ -849,7 +856,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
fn promote_candidate(mut self, candidate: Candidate, next_promoted_id: usize) -> Body<'tcx> {
let def = self.source.source.def_id();
- let mut rvalue = {
+ let (mut rvalue, promoted_op) = {
let promoted = &mut self.promoted;
let promoted_id = Promoted::new(next_promoted_id);
let tcx = self.tcx;
@@ -859,11 +866,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
let args = tcx.erase_regions(GenericArgs::identity_for_item(tcx, def));
let uneval = mir::UnevaluatedConst { def, args, promoted: Some(promoted_id) };
- Operand::Constant(Box::new(ConstOperand {
- span,
- user_ty: None,
- const_: Const::Unevaluated(uneval, ty),
- }))
+ ConstOperand { span, user_ty: None, const_: Const::Unevaluated(uneval, ty) }
};
let blocks = self.source.basic_blocks.as_mut();
@@ -896,22 +899,26 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
let promoted_ref = local_decls.push(promoted_ref);
assert_eq!(self.temps.push(TempState::Unpromotable), promoted_ref);
+ let promoted_operand = promoted_operand(ref_ty, span);
let promoted_ref_statement = Statement {
source_info: statement.source_info,
kind: StatementKind::Assign(Box::new((
Place::from(promoted_ref),
- Rvalue::Use(promoted_operand(ref_ty, span)),
+ Rvalue::Use(Operand::Constant(Box::new(promoted_operand))),
))),
};
self.extra_statements.push((loc, promoted_ref_statement));
- Rvalue::Ref(
- tcx.lifetimes.re_erased,
- *borrow_kind,
- Place {
- local: mem::replace(&mut place.local, promoted_ref),
- projection: List::empty(),
- },
+ (
+ Rvalue::Ref(
+ tcx.lifetimes.re_erased,
+ *borrow_kind,
+ Place {
+ local: mem::replace(&mut place.local, promoted_ref),
+ projection: List::empty(),
+ },
+ ),
+ promoted_operand,
)
};
@@ -923,6 +930,12 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
let span = self.promoted.span;
self.assign(RETURN_PLACE, rvalue, span);
+
+ // Now that we did promotion, we know whether we'll want to add this to `required_consts`.
+ if self.add_to_required {
+ self.source.required_consts.push(promoted_op);
+ }
+
self.promoted
}
}
@@ -982,6 +995,11 @@ fn promote_candidates<'tcx>(
None,
body.tainted_by_errors,
);
+ // We keep `required_consts` of the new MIR body empty. All consts mentioned here have
+ // already been added to the parent MIR's `required_consts` (that is computed before
+ // promotion), and no matter where this promoted const ends up, our parent MIR must be
+ // somewhere in the reachable dependency chain so we can rely on its required consts being
+ // evaluated.
promoted.phase = MirPhase::Analysis(AnalysisPhase::Initial);
let promoter = Promoter {
@@ -991,6 +1009,7 @@ fn promote_candidates<'tcx>(
temps: &mut temps,
extra_statements: &mut extra_statements,
keep_original: false,
+ add_to_required: false,
};
let mut promoted = promoter.promote_candidate(candidate, promotions.len());
diff --git a/tests/ui/rfcs/rfc-1623-static/rfc1623-2.rs b/tests/ui/rfcs/rfc-1623-static/rfc1623-2.rs
index 34739b22b96..f50b72f9279 100644
--- a/tests/ui/rfcs/rfc-1623-static/rfc1623-2.rs
+++ b/tests/ui/rfcs/rfc-1623-static/rfc1623-2.rs
@@ -28,10 +28,6 @@ static SOME_STRUCT: &SomeStruct = &SomeStruct {
f: &id,
//~^ ERROR mismatched types
//~| ERROR mismatched types
- //~| ERROR mismatched types
- //~| ERROR mismatched types
- //~| ERROR implementation of `Fn` is not general enough
- //~| ERROR implementation of `Fn` is not general enough
//~| ERROR implementation of `Fn` is not general enough
//~| ERROR implementation of `Fn` is not general enough
};
diff --git a/tests/ui/rfcs/rfc-1623-static/rfc1623-2.stderr b/tests/ui/rfcs/rfc-1623-static/rfc1623-2.stderr
index dd662db366a..5c98a9d4fb4 100644
--- a/tests/ui/rfcs/rfc-1623-static/rfc1623-2.stderr
+++ b/tests/ui/rfcs/rfc-1623-static/rfc1623-2.stderr
@@ -34,45 +34,5 @@ LL | f: &id,
= note: `fn(&Foo<'2>) -> &Foo<'2> {id::<&Foo<'2>>}` must implement `FnOnce<(&'a Foo<'1>,)>`, for any lifetime `'1`...
= note: ...but it actually implements `FnOnce<(&Foo<'2>,)>`, for some specific lifetime `'2`
-error[E0308]: mismatched types
- --> $DIR/rfc1623-2.rs:28:8
- |
-LL | f: &id,
- | ^^^ one type is more general than the other
- |
- = note: expected trait `for<'a, 'b> Fn(&'a Foo<'b>)`
- found trait `Fn(&Foo<'_>)`
- = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0308]: mismatched types
- --> $DIR/rfc1623-2.rs:28:8
- |
-LL | f: &id,
- | ^^^ one type is more general than the other
- |
- = note: expected trait `for<'a, 'b> Fn(&'a Foo<'b>)`
- found trait `Fn(&Foo<'_>)`
- = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: implementation of `FnOnce` is not general enough
- --> $DIR/rfc1623-2.rs:28:8
- |
-LL | f: &id,
- | ^^^ implementation of `FnOnce` is not general enough
- |
- = note: `fn(&'2 Foo<'_>) -> &'2 Foo<'_> {id::<&'2 Foo<'_>>}` must implement `FnOnce<(&'1 Foo<'b>,)>`, for any lifetime `'1`...
- = note: ...but it actually implements `FnOnce<(&'2 Foo<'_>,)>`, for some specific lifetime `'2`
- = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: implementation of `FnOnce` is not general enough
- --> $DIR/rfc1623-2.rs:28:8
- |
-LL | f: &id,
- | ^^^ implementation of `FnOnce` is not general enough
- |
- = note: `fn(&Foo<'2>) -> &Foo<'2> {id::<&Foo<'2>>}` must implement `FnOnce<(&'a Foo<'1>,)>`, for any lifetime `'1`...
- = note: ...but it actually implements `FnOnce<(&Foo<'2>,)>`, for some specific lifetime `'2`
- = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 8 previous errors
+error: aborting due to 4 previous errors