Auto merge of #73766 - Mark-Simulacrum:beta-next, r=Mark-Simulacrum

[beta] backports

This PR backports the following:

* Make novel structural match violations not a `bug` #73446
* linker: Never pass `-no-pie` to non-gnu linkers #73384
* Disable the `SimplifyArmIdentity` pass #73262
* Allow inference regions when relating consts #73225
* Fix link error with #[thread_local] introduced by #71192 #73065
* Ensure stack when building MIR for matches #72941
* Don't create impl candidates when obligation contains errors #73005

r? @ghost

src/librustc_codegen_ssa/back/linker.rs

@@ -280,7 +280,7 @@ impl<'a> Linker for GccLinker<'a> {
     fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path) {
         match output_kind {
             LinkOutputKind::DynamicNoPicExe => {
-                if !self.is_ld {
+                if !self.is_ld && self.sess.target.target.options.linker_is_gnu {
                     self.cmd.arg("-no-pie");
                 }
             }
@@ -291,7 +291,7 @@ impl<'a> Linker for GccLinker<'a> {
             LinkOutputKind::StaticNoPicExe => {
                 // `-static` works for both gcc wrapper and ld.
                 self.cmd.arg("-static");
-                if !self.is_ld {
+                if !self.is_ld && self.sess.target.target.options.linker_is_gnu {
                     self.cmd.arg("-no-pie");
                 }
             }

src/librustc_middle/ty/relate.rs

@@ -508,16 +508,7 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
     debug!("{}.super_relate_consts(a = {:?}, b = {:?})", relation.tag(), a, b);
     let tcx = relation.tcx();
 
-    let eagerly_eval = |x: &'tcx ty::Const<'tcx>| {
-        // FIXME(eddyb) this doesn't account for lifetime inference variables
-        // being erased by `eval`, *nor* for the polymorphic aspect of `eval`.
-        // That is, we could always use `eval` and it will just return the
-        // old value back if it doesn't succeed.
-        if !x.val.needs_infer() {
-            return x.eval(tcx, relation.param_env()).val;
-        }
-        x.val
-    };
+    let eagerly_eval = |x: &'tcx ty::Const<'tcx>| x.eval(tcx, relation.param_env()).val;
 
     // FIXME(eddyb) doesn't look like everything below checks that `a.ty == b.ty`.
     // We could probably always assert it early, as `const` generic parameters

src/librustc_mir/monomorphize/collector.rs

@@ -586,6 +586,14 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
                     self.output.push(create_fn_mono_item(instance));
                 }
             }
+            mir::Rvalue::ThreadLocalRef(def_id) => {
+                assert!(self.tcx.is_thread_local_static(def_id));
+                let instance = Instance::mono(self.tcx, def_id);
+                if should_monomorphize_locally(self.tcx, &instance) {
+                    trace!("collecting thread-local static {:?}", def_id);
+                    self.output.push(MonoItem::Static(def_id));
+                }
+            }
             _ => { /* not interesting */ }
         }
 

src/librustc_mir/transform/simplify_try.rs

@@ -306,7 +306,11 @@ fn optimization_applies<'tcx>(
 }
 
 impl<'tcx> MirPass<'tcx> for SimplifyArmIdentity {
-    fn run_pass(&self, _: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut Body<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut Body<'tcx>) {
+        if tcx.sess.opts.debugging_opts.mir_opt_level < 2 {
+            return;
+        }
+
         trace!("running SimplifyArmIdentity on {:?}", source);
         let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
         for bb in basic_blocks {

src/librustc_mir_build/build/matches/mod.rs

@@ -10,7 +10,7 @@ use crate::build::ForGuard::{self, OutsideGuard, RefWithinGuard};
 use crate::build::{BlockAnd, BlockAndExtension, Builder};
 use crate::build::{GuardFrame, GuardFrameLocal, LocalsForNode};
 use crate::hair::{self, *};
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::{fx::{FxHashMap, FxHashSet}, stack::ensure_sufficient_stack};
 use rustc_hir::HirId;
 use rustc_index::bit_set::BitSet;
 use rustc_middle::middle::region;
@@ -909,30 +909,32 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             split_or_candidate |= self.simplify_candidate(candidate);
         }
 
-        if split_or_candidate {
-            // At least one of the candidates has been split into subcandidates.
-            // We need to change the candidate list to include those.
-            let mut new_candidates = Vec::new();
+        ensure_sufficient_stack(|| {
+            if split_or_candidate {
+                // At least one of the candidates has been split into subcandidates.
+                // We need to change the candidate list to include those.
+                let mut new_candidates = Vec::new();
 
-            for candidate in candidates {
-                candidate.visit_leaves(|leaf_candidate| new_candidates.push(leaf_candidate));
+                for candidate in candidates {
+                    candidate.visit_leaves(|leaf_candidate| new_candidates.push(leaf_candidate));
+                }
+                self.match_simplified_candidates(
+                    span,
+                    start_block,
+                    otherwise_block,
+                    &mut *new_candidates,
+                    fake_borrows,
+                );
+            } else {
+                self.match_simplified_candidates(
+                    span,
+                    start_block,
+                    otherwise_block,
+                    candidates,
+                    fake_borrows,
+                );
             }
-            self.match_simplified_candidates(
-                span,
-                start_block,
-                otherwise_block,
-                &mut *new_candidates,
-                fake_borrows,
-            );
-        } else {
-            self.match_simplified_candidates(
-                span,
-                start_block,
-                otherwise_block,
-                candidates,
-                fake_borrows,
-            );
-        };
+        });
     }
 
     fn match_simplified_candidates(

src/librustc_mir_build/hair/pattern/const_to_pat.rs

@@ -107,8 +107,15 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 cv.ty, structural
             );
 
+            // This can occur because const qualification treats all associated constants as
+            // opaque, whereas `search_for_structural_match_violation` tries to monomorphize them
+            // before it runs.
+            //
+            // FIXME(#73448): Find a way to bring const qualification into parity with
+            // `search_for_structural_match_violation`.
             if structural.is_none() && mir_structural_match_violation {
-                bug!("MIR const-checker found novel structural match violation");
+                warn!("MIR const-checker found novel structural match violation. See #73448.");
+                return inlined_const_as_pat;
             }
 
             if let Some(non_sm_ty) = structural {

src/librustc_trait_selection/traits/select.rs

@@ -1173,6 +1173,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         // who might care about this case, like coherence, should use
         // that function).
         if candidates.is_empty() {
+            // If there's an error type, 'downgrade' our result from
+            // `Err(Unimplemented)` to `Ok(None)`. This helps us avoid
+            // emitting additional spurious errors, since we're guaranteed
+            // to have emitted at least one.
+            if stack.obligation.references_error() {
+                debug!("no results for error type, treating as ambiguous");
+                return Ok(None);
+            }
             return Err(Unimplemented);
         }
 
@@ -1697,6 +1705,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     ) -> Result<(), SelectionError<'tcx>> {
         debug!("assemble_candidates_from_impls(obligation={:?})", obligation);
 
+        // Essentially any user-written impl will match with an error type,
+        // so creating `ImplCandidates` isn't useful. However, we might
+        // end up finding a candidate elsewhere (e.g. a `BuiltinCandidate` for `Sized)
+        // This helps us avoid overflow: see issue #72839
+        // Since compilation is already guaranteed to fail, this is just
+        // to try to show the 'nicest' possible errors to the user.
+        if obligation.references_error() {
+            return Ok(());
+        }
+
         self.tcx().for_each_relevant_impl(
             obligation.predicate.def_id(),
             obligation.predicate.skip_binder().trait_ref.self_ty(),

src/test/mir-opt/simplify-arm/rustc.id.SimplifyArmIdentity.diff

@@ -26,15 +26,14 @@
       }
 
       bb3: {
--         StorageLive(_3);                 // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
--         _3 = ((_1 as Some).0: u8);       // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
--         StorageLive(_4);                 // scope 1 at $DIR/simplify-arm.rs:11:25: 11:26
--         _4 = _3;                         // scope 1 at $DIR/simplify-arm.rs:11:25: 11:26
--         ((_0 as Some).0: u8) = move _4;  // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
--         discriminant(_0) = 1;            // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
--         StorageDead(_4);                 // scope 1 at $DIR/simplify-arm.rs:11:26: 11:27
--         StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:11:27: 11:28
-+         _0 = move _1;                    // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
+          StorageLive(_3);                 // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
+          _3 = ((_1 as Some).0: u8);       // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
+          StorageLive(_4);                 // scope 1 at $DIR/simplify-arm.rs:11:25: 11:26
+          _4 = _3;                         // scope 1 at $DIR/simplify-arm.rs:11:25: 11:26
+          ((_0 as Some).0: u8) = move _4;  // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
+          discriminant(_0) = 1;            // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
+          StorageDead(_4);                 // scope 1 at $DIR/simplify-arm.rs:11:26: 11:27
+          StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:11:27: 11:28
           goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
       }
 

src/test/mir-opt/simplify-arm/rustc.id.SimplifyBranchSame.diff

@@ -26,7 +26,14 @@
       }
 
       bb3: {
-          _0 = move _1;                    // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
+          StorageLive(_3);                 // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
+          _3 = ((_1 as Some).0: u8);       // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
+          StorageLive(_4);                 // scope 1 at $DIR/simplify-arm.rs:11:25: 11:26
+          _4 = _3;                         // scope 1 at $DIR/simplify-arm.rs:11:25: 11:26
+          ((_0 as Some).0: u8) = move _4;  // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
+          discriminant(_0) = 1;            // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
+          StorageDead(_4);                 // scope 1 at $DIR/simplify-arm.rs:11:26: 11:27
+          StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:11:27: 11:28
           goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
       }
 

src/test/mir-opt/simplify-arm/rustc.id_result.SimplifyArmIdentity.diff

@@ -22,15 +22,14 @@
       }
 
       bb1: {
--         StorageLive(_5);                 // scope 0 at $DIR/simplify-arm.rs:19:13: 19:14
--         _5 = ((_1 as Err).0: i32);       // scope 0 at $DIR/simplify-arm.rs:19:13: 19:14
--         StorageLive(_6);                 // scope 2 at $DIR/simplify-arm.rs:19:23: 19:24
--         _6 = _5;                         // scope 2 at $DIR/simplify-arm.rs:19:23: 19:24
--         ((_0 as Err).0: i32) = move _6;  // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
--         discriminant(_0) = 1;            // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
--         StorageDead(_6);                 // scope 2 at $DIR/simplify-arm.rs:19:24: 19:25
--         StorageDead(_5);                 // scope 0 at $DIR/simplify-arm.rs:19:25: 19:26
-+         _0 = move _1;                    // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
+          StorageLive(_5);                 // scope 0 at $DIR/simplify-arm.rs:19:13: 19:14
+          _5 = ((_1 as Err).0: i32);       // scope 0 at $DIR/simplify-arm.rs:19:13: 19:14
+          StorageLive(_6);                 // scope 2 at $DIR/simplify-arm.rs:19:23: 19:24
+          _6 = _5;                         // scope 2 at $DIR/simplify-arm.rs:19:23: 19:24
+          ((_0 as Err).0: i32) = move _6;  // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
+          discriminant(_0) = 1;            // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
+          StorageDead(_6);                 // scope 2 at $DIR/simplify-arm.rs:19:24: 19:25
+          StorageDead(_5);                 // scope 0 at $DIR/simplify-arm.rs:19:25: 19:26
           goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
       }
 
@@ -39,15 +38,14 @@
       }
 
       bb3: {
--         StorageLive(_3);                 // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
--         _3 = ((_1 as Ok).0: u8);         // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
--         StorageLive(_4);                 // scope 1 at $DIR/simplify-arm.rs:18:21: 18:22
--         _4 = _3;                         // scope 1 at $DIR/simplify-arm.rs:18:21: 18:22
--         ((_0 as Ok).0: u8) = move _4;    // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
--         discriminant(_0) = 0;            // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
--         StorageDead(_4);                 // scope 1 at $DIR/simplify-arm.rs:18:22: 18:23
--         StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:18:23: 18:24
-+         _0 = move _1;                    // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
+          StorageLive(_3);                 // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
+          _3 = ((_1 as Ok).0: u8);         // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
+          StorageLive(_4);                 // scope 1 at $DIR/simplify-arm.rs:18:21: 18:22
+          _4 = _3;                         // scope 1 at $DIR/simplify-arm.rs:18:21: 18:22
+          ((_0 as Ok).0: u8) = move _4;    // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
+          discriminant(_0) = 0;            // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
+          StorageDead(_4);                 // scope 1 at $DIR/simplify-arm.rs:18:22: 18:23
+          StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:18:23: 18:24
           goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
       }
 

src/test/mir-opt/simplify-arm/rustc.id_result.SimplifyBranchSame.diff

@@ -18,27 +18,38 @@
 
       bb0: {
           _2 = discriminant(_1);           // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
--         switchInt(move _2) -> [0isize: bb3, 1isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
-+         goto -> bb1;                     // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
+          switchInt(move _2) -> [0isize: bb3, 1isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
       }
 
       bb1: {
--         _0 = move _1;                    // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
--         goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
--     }
-- 
--     bb2: {
--         unreachable;                     // scope 0 at $DIR/simplify-arm.rs:17:11: 17:12
--     }
-- 
--     bb3: {
-          _0 = move _1;                    // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
--         goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
-+         goto -> bb2;                     // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
+          StorageLive(_5);                 // scope 0 at $DIR/simplify-arm.rs:19:13: 19:14
+          _5 = ((_1 as Err).0: i32);       // scope 0 at $DIR/simplify-arm.rs:19:13: 19:14
+          StorageLive(_6);                 // scope 2 at $DIR/simplify-arm.rs:19:23: 19:24
+          _6 = _5;                         // scope 2 at $DIR/simplify-arm.rs:19:23: 19:24
+          ((_0 as Err).0: i32) = move _6;  // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
+          discriminant(_0) = 1;            // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
+          StorageDead(_6);                 // scope 2 at $DIR/simplify-arm.rs:19:24: 19:25
+          StorageDead(_5);                 // scope 0 at $DIR/simplify-arm.rs:19:25: 19:26
+          goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
       }
 
--     bb4: {
-+     bb2: {
+      bb2: {
+          unreachable;                     // scope 0 at $DIR/simplify-arm.rs:17:11: 17:12
+      }
+
+      bb3: {
+          StorageLive(_3);                 // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
+          _3 = ((_1 as Ok).0: u8);         // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
+          StorageLive(_4);                 // scope 1 at $DIR/simplify-arm.rs:18:21: 18:22
+          _4 = _3;                         // scope 1 at $DIR/simplify-arm.rs:18:21: 18:22
+          ((_0 as Ok).0: u8) = move _4;    // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
+          discriminant(_0) = 0;            // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
+          StorageDead(_4);                 // scope 1 at $DIR/simplify-arm.rs:18:22: 18:23
+          StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:18:23: 18:24
+          goto -> bb4;                     // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
+      }
+
+      bb4: {
           return;                          // scope 0 at $DIR/simplify-arm.rs:21:2: 21:2
       }
   }

src/test/mir-opt/simplify-arm/rustc.id_try.SimplifyArmIdentity.diff

@@ -49,17 +49,16 @@
       }
 
       bb2: {
--         StorageLive(_10);                // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
--         _10 = ((_3 as Ok).0: u8);        // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
--         _2 = _10;                        // scope 5 at $DIR/simplify-arm.rs:24:13: 24:15
--         StorageDead(_10);                // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
-+         _0 = move _3;                    // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
+          StorageLive(_10);                // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
+          _10 = ((_3 as Ok).0: u8);        // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
+          _2 = _10;                        // scope 5 at $DIR/simplify-arm.rs:24:13: 24:15
+          StorageDead(_10);                // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
           StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:24:15: 24:16
--         StorageLive(_11);                // scope 1 at $DIR/simplify-arm.rs:25:8: 25:9
--         _11 = _2;                        // scope 1 at $DIR/simplify-arm.rs:25:8: 25:9
--         ((_0 as Ok).0: u8) = move _11;   // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
--         discriminant(_0) = 0;            // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
--         StorageDead(_11);                // scope 1 at $DIR/simplify-arm.rs:25:9: 25:10
+          StorageLive(_11);                // scope 1 at $DIR/simplify-arm.rs:25:8: 25:9
+          _11 = _2;                        // scope 1 at $DIR/simplify-arm.rs:25:8: 25:9
+          ((_0 as Ok).0: u8) = move _11;   // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
+          discriminant(_0) = 0;            // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
+          StorageDead(_11);                // scope 1 at $DIR/simplify-arm.rs:25:9: 25:10
           StorageDead(_2);                 // scope 0 at $DIR/simplify-arm.rs:26:1: 26:2
           goto -> bb5;                     // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
       }

src/test/mir-opt/simplify-arm/rustc.id_try.SimplifyBranchSame.diff

@@ -49,8 +49,16 @@
       }
 
       bb2: {
-          _0 = move _3;                    // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
+          StorageLive(_10);                // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
+          _10 = ((_3 as Ok).0: u8);        // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
+          _2 = _10;                        // scope 5 at $DIR/simplify-arm.rs:24:13: 24:15
+          StorageDead(_10);                // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
           StorageDead(_3);                 // scope 0 at $DIR/simplify-arm.rs:24:15: 24:16
+          StorageLive(_11);                // scope 1 at $DIR/simplify-arm.rs:25:8: 25:9
+          _11 = _2;                        // scope 1 at $DIR/simplify-arm.rs:25:8: 25:9
+          ((_0 as Ok).0: u8) = move _11;   // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
+          discriminant(_0) = 0;            // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
+          StorageDead(_11);                // scope 1 at $DIR/simplify-arm.rs:25:9: 25:10
           StorageDead(_2);                 // scope 0 at $DIR/simplify-arm.rs:26:1: 26:2
           goto -> bb5;                     // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
       }