Add a forever unstable opt-out of const qualification checks
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f40aaa6827
commit
d0129a613c
8 changed files with 155 additions and 2 deletions
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@ -1300,6 +1300,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
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"print some statistics about AST and HIR"),
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always_encode_mir: bool = (false, parse_bool, [TRACKED],
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"encode MIR of all functions into the crate metadata"),
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unleash_the_miri_inside_of_you: bool = (false, parse_bool, [TRACKED],
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"take the breaks off const evaluation. NOTE: this is unsound"),
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osx_rpath_install_name: bool = (false, parse_bool, [TRACKED],
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"pass `-install_name @rpath/...` to the macOS linker"),
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sanitizer: Option<Sanitizer> = (None, parse_sanitizer, [TRACKED],
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@ -108,6 +108,15 @@ struct Qualifier<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
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promotion_candidates: Vec<Candidate>
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}
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macro_rules! unleash_miri {
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($this:expr) => {{
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if $this.tcx.sess.opts.debugging_opts.unleash_the_miri_inside_of_you {
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$this.tcx.sess.span_warn($this.span, "skipping const checks");
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return;
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}
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}}
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}
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impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
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fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
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def_id: DefId,
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@ -147,6 +156,7 @@ impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
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// categories, but enabling full miri would make that
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// slightly pointless (even with feature-gating).
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fn not_const(&mut self) {
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unleash_miri!(self);
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self.add(Qualif::NOT_CONST);
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if self.mode != Mode::Fn {
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let mut err = struct_span_err!(
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@ -419,6 +429,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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}
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return;
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}
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unleash_miri!(self);
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self.add(Qualif::NOT_CONST);
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if self.mode != Mode::Fn {
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@ -618,6 +629,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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}
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if forbidden_mut {
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unleash_miri!(self);
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self.add(Qualif::NOT_CONST);
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if self.mode != Mode::Fn {
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let mut err = struct_span_err!(self.tcx.sess, self.span, E0017,
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@ -660,6 +672,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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debug!("visit_rvalue: forbidden_mut={:?}", forbidden_mut);
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if forbidden_mut {
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unleash_miri!(self);
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self.add(Qualif::NOT_CONST);
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} else {
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// We might have a candidate for promotion.
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@ -700,6 +713,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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match (cast_in, cast_out) {
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(CastTy::Ptr(_), CastTy::Int(_)) |
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(CastTy::FnPtr, CastTy::Int(_)) => {
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unleash_miri!(self);
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if let Mode::Fn = self.mode {
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// in normal functions, mark such casts as not promotable
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self.add(Qualif::NOT_CONST);
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@ -727,6 +741,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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op == BinOp::Ge || op == BinOp::Gt ||
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op == BinOp::Offset);
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unleash_miri!(self);
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if let Mode::Fn = self.mode {
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// raw pointer operations are not allowed inside promoteds
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self.add(Qualif::NOT_CONST);
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@ -745,6 +760,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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}
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Rvalue::NullaryOp(NullOp::Box, _) => {
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unleash_miri!(self);
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self.add(Qualif::NOT_CONST);
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if self.mode != Mode::Fn {
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let mut err = struct_span_err!(self.tcx.sess, self.span, E0010,
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@ -861,7 +877,13 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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} else {
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// stable const fns or unstable const fns with their feature gate
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// active
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if self.tcx.is_const_fn(def_id) {
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let unleash_miri = self
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.tcx
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.sess
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.opts
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.debugging_opts
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.unleash_the_miri_inside_of_you;
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if self.tcx.is_const_fn(def_id) || unleash_miri {
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is_const_fn = true;
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} else if self.is_const_panic_fn(def_id) {
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// Check the const_panic feature gate.
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@ -1030,6 +1052,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
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// Deny *any* live drops anywhere other than functions.
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if self.mode != Mode::Fn {
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unleash_miri!(self);
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// HACK(eddyb): emulate a bit of dataflow analysis,
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// conservatively, that drop elaboration will do.
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let needs_drop = if let Place::Local(local) = *place {
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@ -1175,7 +1198,9 @@ impl MirPass for QualifyAndPromoteConstants {
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let (temps, candidates) = {
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let mut qualifier = Qualifier::new(tcx, def_id, mir, mode);
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if mode == Mode::ConstFn {
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if tcx.is_min_const_fn(def_id) {
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if tcx.sess.opts.debugging_opts.unleash_the_miri_inside_of_you {
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qualifier.qualify_const();
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} else if tcx.is_min_const_fn(def_id) {
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// enforce `min_const_fn` for stable const fns
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use super::qualify_min_const_fn::is_min_const_fn;
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if let Err((span, err)) = is_min_const_fn(tcx, def_id, mir) {
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30
src/test/ui/consts/miri_unleashed/assoc_const.rs
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30
src/test/ui/consts/miri_unleashed/assoc_const.rs
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@ -0,0 +1,30 @@
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// compile-flags: -Zunleash-the-miri-inside-of-you
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#![allow(const_err)]
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// a test demonstrating why we do need to run static const qualification on associated constants
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// instead of just checking the final constant
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trait Foo<T> {
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const X: T;
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}
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trait Bar<T, U: Foo<T>> {
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const F: u32 = (U::X, 42).1; //~ WARN skipping const checks
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}
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impl Foo<u32> for () {
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const X: u32 = 42;
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}
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impl Foo<Vec<u32>> for String {
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const X: Vec<u32> = Vec::new();
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}
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impl Bar<u32, ()> for () {}
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impl Bar<Vec<u32>, String> for String {}
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fn main() {
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// this is fine, but would have been forbidden by the static checks on `F`
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let x = <() as Bar<u32, ()>>::F;
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// this test only causes errors due to the line below, so post-monomorphization
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let y = <String as Bar<Vec<u32>, String>>::F; //~ ERROR erroneous constant
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}
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15
src/test/ui/consts/miri_unleashed/assoc_const.stderr
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15
src/test/ui/consts/miri_unleashed/assoc_const.stderr
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@ -0,0 +1,15 @@
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warning: skipping const checks
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--> $DIR/assoc_const.rs:12:31
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LL | const F: u32 = (U::X, 42).1; //~ WARN skipping const checks
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| ^
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error[E0080]: erroneous constant used
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--> $DIR/assoc_const.rs:29:13
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LL | let y = <String as Bar<Vec<u32>, String>>::F; //~ ERROR erroneous constant
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0080`.
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28
src/test/ui/consts/miri_unleashed/assoc_const_2.rs
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28
src/test/ui/consts/miri_unleashed/assoc_const_2.rs
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@ -0,0 +1,28 @@
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#![allow(const_err)]
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// a test demonstrating that const qualification cannot prevent monomorphization time errors
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trait Foo {
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const X: u32;
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}
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trait Bar<U: Foo> {
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const F: u32 = 100 / U::X;
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}
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impl Foo for () {
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const X: u32 = 42;
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}
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impl Foo for String {
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const X: u32 = 0;
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}
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impl Bar<()> for () {}
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impl Bar<String> for String {}
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fn main() {
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let x = <() as Bar<()>>::F;
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// this test only causes errors due to the line below, so post-monomorphization
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let y = <String as Bar<String>>::F; //~ ERROR erroneous constant
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}
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9
src/test/ui/consts/miri_unleashed/assoc_const_2.stderr
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9
src/test/ui/consts/miri_unleashed/assoc_const_2.stderr
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@ -0,0 +1,9 @@
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error[E0080]: erroneous constant used
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--> $DIR/assoc_const_2.rs:27:13
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LL | let y = <String as Bar<String>>::F; //~ ERROR erroneous constant
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0080`.
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@ -0,0 +1,27 @@
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#![allow(const_err)]
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// a test demonstrating why we do need to run static const qualification on associated constants
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// instead of just checking the final constant
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trait Foo<T> {
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const X: T;
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}
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trait Bar<T, U: Foo<T>> {
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const F: u32 = (U::X, 42).1; //~ ERROR destructors cannot be evaluated at compile-time
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}
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impl Foo<u32> for () {
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const X: u32 = 42;
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}
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impl Foo<Vec<u32>> for String {
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const X: Vec<u32> = Vec::new(); //~ ERROR not yet stable as a const fn
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}
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impl Bar<u32, ()> for () {}
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impl Bar<Vec<u32>, String> for String {}
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fn main() {
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let x = <() as Bar<u32, ()>>::F;
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let y = <String as Bar<Vec<u32>, String>>::F;
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}
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@ -0,0 +1,17 @@
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error[E0493]: destructors cannot be evaluated at compile-time
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--> $DIR/feature-gate-unleash_the_miri_inside_of_you.rs:11:20
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LL | const F: u32 = (U::X, 42).1; //~ ERROR destructors cannot be evaluated at compile-time
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| ^^^^^^^^^^ constants cannot evaluate destructors
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error: `<std::vec::Vec<T>>::new` is not yet stable as a const fn
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--> $DIR/feature-gate-unleash_the_miri_inside_of_you.rs:18:25
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LL | const X: Vec<u32> = Vec::new(); //~ ERROR not yet stable as a const fn
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| ^^^^^^^^^^
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= help: add `#![feature(const_vec_new)]` to the crate attributes to enable
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0493`.
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