remove a hack that seems to only benefit a few very special cases
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@ -22,7 +22,7 @@ use rustc_middle::ty::cast::CastTy;
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use rustc_middle::ty::subst::InternalSubsts;
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use rustc_middle::ty::subst::InternalSubsts;
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use rustc_middle::ty::{self, List, TyCtxt, TypeFoldable};
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use rustc_middle::ty::{self, List, TyCtxt, TypeFoldable};
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use rustc_span::symbol::sym;
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use rustc_span::symbol::sym;
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use rustc_span::{Span, DUMMY_SP};
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use rustc_span::Span;
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use rustc_index::vec::{Idx, IndexVec};
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use rustc_index::vec::{Idx, IndexVec};
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use rustc_target::spec::abi::Abi;
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use rustc_target::spec::abi::Abi;
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@ -326,41 +326,16 @@ impl<'tcx> Validator<'_, 'tcx> {
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if place.projection.contains(&ProjectionElem::Deref) {
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if place.projection.contains(&ProjectionElem::Deref) {
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return Err(Unpromotable);
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return Err(Unpromotable);
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}
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}
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if self.qualif_local::<qualifs::NeedsDrop>(place.local) {
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let mut has_mut_interior =
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return Err(Unpromotable);
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self.qualif_local::<qualifs::HasMutInterior>(place.local);
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// HACK(eddyb) this should compute the same thing as
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// `<HasMutInterior as Qualif>::in_projection` from
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// `check_consts::qualifs` but without recursion.
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if has_mut_interior {
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// This allows borrowing fields which don't have
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// `HasMutInterior`, from a type that does, e.g.:
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// `let _: &'static _ = &(Cell::new(1), 2).1;`
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let mut place_projection = &place.projection[..];
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// FIXME(eddyb) use a forward loop instead of a reverse one.
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while let &[ref proj_base @ .., elem] = place_projection {
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// FIXME(eddyb) this is probably excessive, with
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// the exception of `union` member accesses.
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let ty =
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Place::ty_from(place.local, proj_base, self.body, self.tcx)
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.projection_ty(self.tcx, elem)
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.ty;
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if ty.is_freeze(self.tcx.at(DUMMY_SP), self.param_env) {
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has_mut_interior = false;
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break;
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}
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place_projection = proj_base;
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}
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}
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}
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// FIXME(eddyb) this duplicates part of `validate_rvalue`.
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// FIXME(eddyb) this duplicates part of `validate_rvalue`.
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let has_mut_interior =
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self.qualif_local::<qualifs::HasMutInterior>(place.local);
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if has_mut_interior {
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if has_mut_interior {
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return Err(Unpromotable);
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return Err(Unpromotable);
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}
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}
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if self.qualif_local::<qualifs::NeedsDrop>(place.local) {
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return Err(Unpromotable);
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}
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if let BorrowKind::Mut { .. } = kind {
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if let BorrowKind::Mut { .. } = kind {
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let ty = place.ty(self.body, self.tcx).ty;
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let ty = place.ty(self.body, self.tcx).ty;
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@ -692,28 +667,7 @@ impl<'tcx> Validator<'_, 'tcx> {
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self.validate_place(place)?;
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self.validate_place(place)?;
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// HACK(eddyb) this should compute the same thing as
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let has_mut_interior = self.qualif_local::<qualifs::HasMutInterior>(place.local);
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// `<HasMutInterior as Qualif>::in_projection` from
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// `check_consts::qualifs` but without recursion.
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let mut has_mut_interior =
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self.qualif_local::<qualifs::HasMutInterior>(place.local);
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if has_mut_interior {
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let mut place_projection = place.projection;
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// FIXME(eddyb) use a forward loop instead of a reverse one.
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while let &[ref proj_base @ .., elem] = place_projection {
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// FIXME(eddyb) this is probably excessive, with
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// the exception of `union` member accesses.
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let ty = Place::ty_from(place.local, proj_base, self.body, self.tcx)
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.projection_ty(self.tcx, elem)
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.ty;
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if ty.is_freeze(self.tcx.at(DUMMY_SP), self.param_env) {
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has_mut_interior = false;
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break;
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}
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place_projection = proj_base;
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}
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}
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if has_mut_interior {
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if has_mut_interior {
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return Err(Unpromotable);
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return Err(Unpromotable);
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}
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}
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@ -34,7 +34,14 @@ const TEST_UNION: () = {
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let _x: &'static i32 = &unsafe { U { x: 0 }.x }; //~ ERROR temporary value dropped while borrowed
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let _x: &'static i32 = &unsafe { U { x: 0 }.x }; //~ ERROR temporary value dropped while borrowed
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};
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};
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// In a `const`, we do not promote things with interior mutability. Not even if we "project it away".
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const TEST_INTERIOR_MUT: () = {
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// The "0." case is already ruled out by not permitting any interior mutability in `const`.
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let _val: &'static _ = &(Cell::new(1), 2).1; //~ ERROR temporary value dropped while borrowed
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};
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fn main() {
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fn main() {
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// We must not promote things with interior mutability.
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// We must not promote things with interior mutability. Not even if we "project it away".
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let _val: &'static _ = &(Cell::new(1), 2).0; //~ ERROR temporary value dropped while borrowed
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let _val: &'static _ = &(Cell::new(1), 2).0; //~ ERROR temporary value dropped while borrowed
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let _val: &'static _ = &(Cell::new(1), 2).1; //~ ERROR temporary value dropped while borrowed
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}
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}
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@ -49,15 +49,36 @@ LL | };
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| - temporary value is freed at the end of this statement
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| - temporary value is freed at the end of this statement
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error[E0716]: temporary value dropped while borrowed
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error[E0716]: temporary value dropped while borrowed
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--> $DIR/promote-not.rs:39:29
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--> $DIR/promote-not.rs:40:29
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LL | let _val: &'static _ = &(Cell::new(1), 2).1;
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| ---------- ^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use
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| type annotation requires that borrow lasts for `'static`
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LL | };
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| - temporary value is freed at the end of this statement
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error[E0716]: temporary value dropped while borrowed
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--> $DIR/promote-not.rs:45:29
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LL | let _val: &'static _ = &(Cell::new(1), 2).0;
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LL | let _val: &'static _ = &(Cell::new(1), 2).0;
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| ---------- ^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use
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| ---------- ^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use
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| type annotation requires that borrow lasts for `'static`
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| type annotation requires that borrow lasts for `'static`
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LL | let _val: &'static _ = &(Cell::new(1), 2).1;
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LL | }
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| - temporary value is freed at the end of this statement
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error[E0716]: temporary value dropped while borrowed
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--> $DIR/promote-not.rs:46:29
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LL | let _val: &'static _ = &(Cell::new(1), 2).1;
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| ---------- ^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use
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| type annotation requires that borrow lasts for `'static`
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LL | }
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LL | }
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| - temporary value is freed at the end of this statement
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| - temporary value is freed at the end of this statement
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error: aborting due to 6 previous errors
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error: aborting due to 8 previous errors
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For more information about this error, try `rustc --explain E0716`.
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For more information about this error, try `rustc --explain E0716`.
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