Auto merge of #99177 - Dylan-DPC:rollup-m0k9q2w, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #98622 (rustc_target: Flip the default for `TargetOptions::executables` to true)
 - #98633 (Fix last `let_chains` blocker)
 - #98972 (Suggest adding a missing zero to a floating point number)
 - #99038 (Some more `EarlyBinder` cleanups)
 - #99154 (use PlaceRef::iter_projections to fix old FIXME)
 - #99171 (Put back UI test regex)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_middle/src/mir/visit.rs

@@ -1111,11 +1111,9 @@ macro_rules! visit_place_fns {
             context: PlaceContext,
             location: Location,
         ) {
-            // FIXME: Use PlaceRef::iter_projections, once that exists.
-            let mut cursor = place_ref.projection;
-            while let &[ref proj_base @ .., elem] = cursor {
-                cursor = proj_base;
-                self.visit_projection_elem(place_ref.local, cursor, elem, context, location);
+            for (base, elem) in place_ref.iter_projections().rev() {
+                let base_proj = base.projection;
+                self.visit_projection_elem(place_ref.local, base_proj, elem, context, location);
             }
         }
 

compiler/rustc_middle/src/ty/generics.rs

@@ -85,10 +85,10 @@ impl GenericParamDef {
     ) -> Option<EarlyBinder<ty::GenericArg<'tcx>>> {
         match self.kind {
             GenericParamDefKind::Type { has_default, .. } if has_default => {
-                Some(EarlyBinder(tcx.type_of(self.def_id).into()))
+                Some(tcx.bound_type_of(self.def_id).map_bound(|t| t.into()))
             }
             GenericParamDefKind::Const { has_default } if has_default => {
-                Some(EarlyBinder(tcx.const_param_default(self.def_id).into()))
+                Some(tcx.bound_const_param_default(self.def_id).map_bound(|c| c.into()))
             }
             _ => None,
         }

compiler/rustc_middle/src/ty/sty.rs

@@ -932,6 +932,10 @@ impl<T> EarlyBinder<T> {
         let value = f(self.0)?;
         Ok(EarlyBinder(value))
     }
+
+    pub fn rebind<U>(&self, value: U) -> EarlyBinder<U> {
+        EarlyBinder(value)
+    }
 }
 
 impl<T> EarlyBinder<Option<T>> {

compiler/rustc_middle/src/ty/util.rs

@@ -676,6 +676,10 @@ impl<'tcx> TyCtxt<'tcx> {
     ) -> ty::EarlyBinder<&'tcx ty::List<ty::Predicate<'tcx>>> {
         ty::EarlyBinder(self.item_bounds(def_id))
     }
+
+    pub fn bound_const_param_default(self, def_id: DefId) -> ty::EarlyBinder<ty::Const<'tcx>> {
+        ty::EarlyBinder(self.const_param_default(def_id))
+    }
 }
 
 struct OpaqueTypeExpander<'tcx> {

compiler/rustc_mir_transform/src/shim.rs

@@ -537,13 +537,12 @@ fn build_call_shim<'tcx>(
     };
 
     let def_id = instance.def_id();
-    let sig = tcx.fn_sig(def_id);
-    let mut sig = tcx.erase_late_bound_regions(sig);
+    let sig = tcx.bound_fn_sig(def_id);
+    let sig = sig.map_bound(|sig| tcx.erase_late_bound_regions(sig));
 
     assert_eq!(sig_substs.is_some(), !instance.has_polymorphic_mir_body());
-    if let Some(sig_substs) = sig_substs {
-        sig = EarlyBinder(sig).subst(tcx, sig_substs);
-    }
+    let mut sig =
+        if let Some(sig_substs) = sig_substs { sig.subst(tcx, sig_substs) } else { sig.0 };
 
     if let CallKind::Indirect(fnty) = call_kind {
         // `sig` determines our local decls, and thus the callee type in the `Call` terminator. This

compiler/rustc_parse/src/parser/expr.rs

@@ -1393,7 +1393,9 @@ impl<'a> Parser<'a> {
             self.parse_yield_expr(attrs)
         } else if self.is_do_yeet() {
             self.parse_yeet_expr(attrs)
-        } else if self.eat_keyword(kw::Let) {
+        } else if self.check_keyword(kw::Let) {
+            self.manage_let_chains_context();
+            self.bump();
             self.parse_let_expr(attrs)
         } else if self.eat_keyword(kw::Underscore) {
             Ok(self.mk_expr(self.prev_token.span, ExprKind::Underscore, attrs))
@@ -2355,16 +2357,30 @@ impl<'a> Parser<'a> {
         Ok(cond)
     }
 
+    // Checks if `let` is in an invalid position like `let x = let y = 1;` or
+    // if the current `let` is in a let_chains context but nested in another
+    // expression like `if let Some(_) = _opt && [1, 2, 3][let _ = ()] = 1`.
+    //
+    // This method expects that the current token is `let`.
+    fn manage_let_chains_context(&mut self) {
+        debug_assert!(matches!(self.token.kind, TokenKind::Ident(kw::Let, _)));
+        let is_in_a_let_chains_context_but_nested_in_other_expr = self.let_expr_allowed
+            && !matches!(
+                self.prev_token.kind,
+                TokenKind::AndAnd
+                    | TokenKind::CloseDelim(Delimiter::Brace)
+                    | TokenKind::Ident(kw::If, _)
+                    | TokenKind::Ident(kw::While, _)
+            );
+        if !self.let_expr_allowed || is_in_a_let_chains_context_but_nested_in_other_expr {
+            self.struct_span_err(self.token.span, "expected expression, found `let` statement")
+                .emit();
+        }
+    }
+
     /// Parses a `let $pat = $expr` pseudo-expression.
     /// The `let` token has already been eaten.
     fn parse_let_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> {
-        if !self.let_expr_allowed {
-            self.struct_span_err(
-                self.prev_token.span,
-                "expected expression, found `let` statement",
-            )
-            .emit();
-        }
         let lo = self.prev_token.span;
         let pat = self.parse_pat_allow_top_alt(
             None,

compiler/rustc_target/src/spec/aarch64_unknown_none.rs

@@ -13,7 +13,6 @@ pub fn target() -> Target {
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
         linker: Some("rust-lld".into()),
         features: "+strict-align,+neon,+fp-armv8".into(),
-        executables: true,
         relocation_model: RelocModel::Static,
         disable_redzone: true,
         max_atomic_width: Some(128),

compiler/rustc_target/src/spec/aarch64_unknown_none_softfloat.rs

@@ -14,7 +14,6 @@ pub fn target() -> Target {
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
         linker: Some("rust-lld".into()),
         features: "+strict-align,-neon,-fp-armv8".into(),
-        executables: true,
         relocation_model: RelocModel::Static,
         disable_redzone: true,
         max_atomic_width: Some(128),

compiler/rustc_target/src/spec/apple_base.rs

@@ -25,7 +25,6 @@ pub fn opts(os: &'static str) -> TargetOptions {
         function_sections: false,
         dynamic_linking: true,
         linker_is_gnu: false,
-        executables: true,
         families: cvs!["unix"],
         is_like_osx: true,
         default_dwarf_version: 2,

compiler/rustc_target/src/spec/apple_sdk_base.rs

@@ -54,7 +54,6 @@ pub fn opts(os: &'static str, arch: Arch) -> TargetOptions {
         abi: target_abi(arch).into(),
         cpu: target_cpu(arch).into(),
         dynamic_linking: false,
-        executables: true,
         link_env_remove: link_env_remove(arch),
         has_thread_local: false,
         ..super::apple_base::opts(os)