rust-lang · rust-bors · Jul 27, 2026 · Jul 14, 2026 · Jul 18, 2026 · Jul 18, 2026
diff --git a/Cargo.lock b/Cargo.lock
@@ -5575,9 +5575,9 @@ dependencies = [
 
 [[package]]
 name = "thin-vec"
-version = "0.2.18"
+version = "0.2.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0f7e269b48f0a7dd0146680fa24b50cc67fc0373f086a5b2f99bd084639b482"
+checksum = "79def32ffcd477db1ff26f76dab9e3a91f0bd42a85ca96577089b24623056f9d"
 
 [[package]]
 name = "thiserror"

diff --git a/compiler/rustc_ast/Cargo.toml b/compiler/rustc_ast/Cargo.toml
@@ -15,6 +15,6 @@ rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_ast_lowering/Cargo.toml b/compiler/rustc_ast_lowering/Cargo.toml
@@ -22,6 +22,6 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_ast_pretty/Cargo.toml b/compiler/rustc_ast_pretty/Cargo.toml
@@ -13,5 +13,5 @@ rustc_span = { path = "../rustc_span" }
 
 [dev-dependencies]
 # tidy-alphabetical-start
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_attr_parsing/Cargo.toml b/compiler/rustc_attr_parsing/Cargo.toml
@@ -20,5 +20,5 @@ rustc_parse_format = { path = "../rustc_parse_format" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
@@ -1243,6 +1243,9 @@ impl<'diag, 'tcx> MirBorrowckCtxt<'_, 'diag, 'tcx> {
                 }
             } else if j == 0 {
                 err.span_label(binding_span, "data moved here");
+            } else if j == 5 && binds_to.len() > 6 && !self.infcx.tcx.sess.opts.verbose {
+                err.note(format!("...and {} other places", binds_to.len() - 5));
+                break;
             } else {
                 err.span_label(binding_span, "...and here");
             }

diff --git a/compiler/rustc_builtin_macros/Cargo.toml b/compiler/rustc_builtin_macros/Cargo.toml
@@ -29,7 +29,7 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
 

diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -3,6 +3,7 @@ use std::collections::hash_map::Entry::*;
 use rustc_abi::{CanonAbi, X86Call};
 use rustc_ast::expand::allocator::{AllocatorKind, NO_ALLOC_SHIM_IS_UNSTABLE, global_fn_name};
 use rustc_data_structures::unord::UnordMap;
+use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LOCAL_CRATE, LocalDefId};
 use rustc_middle::bug;
@@ -87,6 +88,11 @@ pub fn reachable_non_generics_helper(tcx: TyCtxt<'_>) -> DefIdMap<SymbolExportIn
 
             // Only consider nodes that actually have exported symbols.
             match tcx.def_kind(def_id) {
+                DefKind::Fn | DefKind::AssocFn
+                    if tcx.constness(def_id) == hir::Constness::Const { always: true } =>
+                {
+                    return None;
+                }
                 DefKind::Fn | DefKind::Static { .. } => {}
                 DefKind::AssocFn if tcx.impl_of_assoc(def_id.to_def_id()).is_some() => {}
                 _ => return None,

diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
@@ -30,7 +30,7 @@ smallvec = { version = "1.8.1", features = [
 ] }
 stacker = "0.1.17"
 tempfile = "3.2"
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
 

diff --git a/compiler/rustc_expand/Cargo.toml b/compiler/rustc_expand/Cargo.toml
@@ -30,6 +30,6 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 scoped-tls = "1.0"
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_hir/Cargo.toml b/compiler/rustc_hir/Cargo.toml
@@ -23,6 +23,6 @@ rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_infer/Cargo.toml b/compiler/rustc_infer/Cargo.toml
@@ -17,6 +17,6 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_span = { path = "../rustc_span" }
 rustc_type_ir = { path = "../rustc_type_ir" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_infer/src/infer/context.rs b/compiler/rustc_infer/src/infer/context.rs
@@ -529,7 +529,10 @@ impl<'a, 'tcx> ty::TypeFolder<TyCtxt<'tcx>> for LowerUniverseFolder<'a, 'tcx> {
         match c.kind() {
             ty::ConstKind::Infer(ty::InferConst::Var(vid)) => {
                 let vid = self.infcx.root_const_var(vid);
-                let universe = self.infcx.try_resolve_const_var(vid).unwrap_err();
+                let universe = match self.infcx.try_resolve_const_var(vid) {
+                    Ok(value) => return value.fold_with(self),
+                    Err(universe) => universe,
+                };
                 if self.for_universe.can_name(universe) {
                     c
                 } else {

diff --git a/compiler/rustc_infer/src/infer/relate/generalize.rs b/compiler/rustc_infer/src/infer/relate/generalize.rs
@@ -752,7 +752,7 @@ impl<'tcx> TypeRelation<TyCtxt<'tcx>> for Generalizer<'_, 'tcx> {
                 // Hack: Fall back to old behavior if GCE is enabled (it used to just be the Yes
                 // path), as doing this new No path breaks some GCE things. I expect GCE to be
                 // ripped out soon so this shouldn't matter soon.
-                if !tcx.features().generic_const_exprs() {
+                if self.infcx.next_trait_solver() || !tcx.features().generic_const_exprs() {
                     self.generalize_alias_term(alias_const.into()).map(|v| v.expect_const())
                 } else {
                     let ty::AliasConst { kind, args, .. } = alias_const;

diff --git a/compiler/rustc_middle/Cargo.toml b/compiler/rustc_middle/Cargo.toml
@@ -33,7 +33,7 @@ rustc_target = { path = "../rustc_target" }
 rustc_thread_pool = { path = "../rustc_thread_pool" }
 rustc_type_ir = { path = "../rustc_type_ir" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
 

diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
@@ -1677,6 +1677,15 @@ impl<'v> RootCollector<'_, 'v> {
             && match self.strategy {
                 MonoItemCollectionStrategy::Eager => {
                     !matches!(self.tcx.codegen_fn_attrs(def_id).inline, InlineAttr::Force { .. })
+                    // comptime fns can't be codegenned, so we need to prevent collecting them even
+                    // with link-dead-code. Lazy mode prevents them by them not showing up in
+                    // `is_reachable_non_generic` (and `entry_fn` can't be comptime).
+                    && match self.tcx.def_kind(def_id) {
+                        DefKind::Fn | DefKind::AssocFn => {
+                            self.tcx.constness(def_id) != hir::Constness::Const { always: true }
+                        }
+                        _ => true,
+                    }
                 }
                 MonoItemCollectionStrategy::Lazy => {
                     self.entry_fn.and_then(|(id, _)| id.as_local()) == Some(def_id)

diff --git a/compiler/rustc_next_trait_solver/src/canonical/mod.rs b/compiler/rustc_next_trait_solver/src/canonical/mod.rs
@@ -391,12 +391,10 @@ where
         }
 
         let infcx = self.infcx;
-        // FIXME: make this a debug_assert.
-        // Currently proof tree evaluation can unify infer vars in original
-        // vars while not resolving them.
-        // See `tests/ui/traits/next-solver/transmute-from-async-closure.rs`
+        // Proof tree evaluation can unify inference variables in the original
+        // values without eagerly resolving them.
         let a = infcx.shallow_resolve_const(a);
-        debug_assert_eq!(b, infcx.shallow_resolve_const(b));
+        let b = infcx.shallow_resolve_const(b);
         match (a.kind(), b.kind()) {
             (
                 ty::ConstKind::Infer(ty::InferConst::Var(a_vid)),

diff --git a/compiler/rustc_parse/Cargo.toml b/compiler/rustc_parse/Cargo.toml
@@ -17,7 +17,7 @@ rustc_lexer = { path = "../rustc_lexer" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 unicode-normalization = "0.1.25"
 unicode-width = "0.2.2"

diff --git a/compiler/rustc_resolve/Cargo.toml b/compiler/rustc_resolve/Cargo.toml
@@ -26,6 +26,6 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_serialize/Cargo.toml b/compiler/rustc_serialize/Cargo.toml
@@ -8,7 +8,7 @@ edition = "2024"
 indexmap = "2.0.0"
 rustc_hashes = { path = "../rustc_hashes" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 # tidy-alphabetical-end
 
 [dev-dependencies]

diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs
@@ -87,6 +87,7 @@
 //! virtually impossible. Thus, symbol hash generation exclusively relies on
 //! DefPaths which are much more robust in the face of changes to the code base.
 
+use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
@@ -240,6 +241,10 @@ fn compute_symbol_name<'tcx>(
 ) -> String {
     let def_id = instance.def_id();
     let args = instance.args;
+    let def_kind = tcx.def_kind(instance.def_id());
+    if let DefKind::Fn | DefKind::AssocFn = def_kind {
+        debug_assert!(tcx.constness(instance.def_id()) != hir::Constness::Const { always: true });
+    }
 
     debug!("symbol_name(def_id={:?}, args={:?})", def_id, args);
 
@@ -254,7 +259,7 @@ fn compute_symbol_name<'tcx>(
     // visibility) symbol. This means that multiple crates may do the same
     // and we want to be sure to avoid any symbol conflicts here.
     let is_globally_shared_function = matches!(
-        tcx.def_kind(instance.def_id()),
+        def_kind,
         DefKind::Fn
             | DefKind::AssocFn
             | DefKind::Closure

diff --git a/compiler/rustc_trait_selection/Cargo.toml b/compiler/rustc_trait_selection/Cargo.toml
@@ -19,6 +19,6 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_transmute = { path = "../rustc_transmute", features = ["rustc"] }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -949,12 +949,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     }
                 } else if let Some(impl_did) = impl_did.as_local()
                     && let item = self.tcx.hir_expect_item(impl_did)
-                    && let hir::ItemKind::Impl(item) = item.kind
-                    && let Some(of_trait) = item.of_trait
+                    && let hir::ItemKind::Impl(impl_) = item.kind
+                    && impl_.of_trait.is_some()
                 {
                     // trait is const, impl is local and not const
                     diag.span_suggestion_verbose(
-                        of_trait.trait_ref.path.span.shrink_to_lo(),
+                        item.span.shrink_to_lo(),
                         format!("make the `impl` of trait `{trait_name}` `const`"),
                         "const ".to_string(),
                         Applicability::MaybeIncorrect,

diff --git a/compiler/rustc_type_ir/Cargo.toml b/compiler/rustc_type_ir/Cargo.toml
@@ -23,7 +23,7 @@ rustc_type_ir_macros = { path = "../rustc_type_ir_macros" }
 smallvec = { version = "1.8.1", default-features = false, features = [
     "const_generics",
 ] }
-thin-vec = "0.2.18"
+thin-vec = "0.2.19"
 tracing = "0.1"
 # tidy-alphabetical-end