Auto merge of rust-lang#89047 - GuillaumeGomez:rollup-29gmr02, r=GuillaumeGomez

Rollup of 10 pull requests

Successful merges:

 - rust-lang#86422 (Emit clearer diagnostics for parens around `for` loop heads)
 - rust-lang#87460 (Point to closure when emitting 'cannot move out' for captured variable)
 - rust-lang#87566 (Recover invalid assoc type bounds using `==`)
 - rust-lang#88666 (Improve build command for compiler docs)
 - rust-lang#88899 (Do not issue E0071 if a type error has already been reported)
 - rust-lang#88949 (Fix handling of `hir::GenericArg::Infer` in `wrong_number_of_generic_args.rs`)
 - rust-lang#88953 (Add chown functions to std::os::unix::fs to change the owner and group of files)
 - rust-lang#88954 (Allow `panic!("{}", computed_str)` in const fn.)
 - rust-lang#88964 (Add rustdoc version into the help popup)
 - rust-lang#89012 (Suggest removing `#![feature]` for library features that have been stabilized)

Failed merges:

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

Author: bors

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -702,10 +702,16 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
 }
 
 fn maybe_stage_features(sess: &Session, krate: &ast::Crate) {
+    // checks if `#![feature]` has been used to enable any lang feature
+    // does not check the same for lib features unless there's at least one
+    // declared lang feature
     use rustc_errors::Applicability;
 
     if !sess.opts.unstable_features.is_nightly_build() {
         let lang_features = &sess.features_untracked().declared_lang_features;
+        if lang_features.len() == 0 {
+            return;
+        }
         for attr in krate.attrs.iter().filter(|attr| attr.has_name(sym::feature)) {
             let mut err = struct_span_err!(
                 sess.parse_sess.span_diagnostic,

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -336,15 +336,15 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 if def_id.as_local() == Some(self.mir_def_id()) && upvar_field.is_some() =>
             {
                 let closure_kind_ty = closure_substs.as_closure().kind_ty();
-                let closure_kind = closure_kind_ty.to_opt_closure_kind();
-                let capture_description = match closure_kind {
-                    Some(ty::ClosureKind::Fn) => "captured variable in an `Fn` closure",
-                    Some(ty::ClosureKind::FnMut) => "captured variable in an `FnMut` closure",
+                let closure_kind = match closure_kind_ty.to_opt_closure_kind() {
+                    Some(kind @ (ty::ClosureKind::Fn | ty::ClosureKind::FnMut)) => kind,
                     Some(ty::ClosureKind::FnOnce) => {
                         bug!("closure kind does not match first argument type")
                     }
                     None => bug!("closure kind not inferred by borrowck"),
                 };
+                let capture_description =
+                    format!("captured variable in an `{}` closure", closure_kind);
 
                 let upvar = &self.upvars[upvar_field.unwrap().index()];
                 let upvar_hir_id = upvar.place.get_root_variable();
@@ -368,6 +368,10 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 let mut diag = self.cannot_move_out_of(span, &place_description);
 
                 diag.span_label(upvar_span, "captured outer variable");
+                diag.span_label(
+                    self.body.span,
+                    format!("captured by this `{}` closure", closure_kind),
+                );
 
                 diag
             }

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -36,12 +36,17 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>> {
         let def_id = instance.def_id();
         if Some(def_id) == self.tcx.lang_items().panic_fn()
             || Some(def_id) == self.tcx.lang_items().panic_str()
+            || Some(def_id) == self.tcx.lang_items().panic_display()
             || Some(def_id) == self.tcx.lang_items().begin_panic_fn()
         {
-            // &str
+            // &str or &&str
             assert!(args.len() == 1);
 
-            let msg_place = self.deref_operand(&args[0])?;
+            let mut msg_place = self.deref_operand(&args[0])?;
+            while msg_place.layout.ty.is_ref() {
+                msg_place = self.deref_operand(&msg_place.into())?;
+            }
+
             let msg = Symbol::intern(self.read_str(&msg_place)?);
             let span = self.find_closest_untracked_caller_location();
             let (file, line, col) = self.location_triple_for_span(span);

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -888,6 +888,10 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> {
                 if is_lang_panic_fn(tcx, callee) {
                     self.check_op(ops::Panic);
 
+                    // `begin_panic` and `panic_display` are generic functions that accept
+                    // types other than str. Check to enforce that only str can be used in
+                    // const-eval.
+
                     // const-eval of the `begin_panic` fn assumes the argument is `&str`
                     if Some(callee) == tcx.lang_items().begin_panic_fn() {
                         match args[0].ty(&self.ccx.body.local_decls, tcx).kind() {
@@ -896,6 +900,15 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> {
                         }
                     }
 
+                    // const-eval of the `panic_display` fn assumes the argument is `&&str`
+                    if Some(callee) == tcx.lang_items().panic_display() {
+                        match args[0].ty(&self.ccx.body.local_decls, tcx).kind() {
+                            ty::Ref(_, ty, _) if matches!(ty.kind(), ty::Ref(_, ty, _) if ty.is_str()) =>
+                                {}
+                            _ => self.check_op(ops::PanicNonStr),
+                        }
+                    }
+
                     return;
                 }
 

compiler/rustc_const_eval/src/transform/check_consts/mod.rs

@@ -79,6 +79,7 @@ pub fn is_lang_panic_fn(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool {
     // Keep in sync with what that function handles!
     Some(def_id) == tcx.lang_items().panic_fn()
         || Some(def_id) == tcx.lang_items().panic_str()
+        || Some(def_id) == tcx.lang_items().panic_display()
         || Some(def_id) == tcx.lang_items().begin_panic_fn()
         || Some(def_id) == tcx.lang_items().panic_fmt()
         || Some(def_id) == tcx.lang_items().begin_panic_fmt()

compiler/rustc_error_codes/src/error_codes/E0071.md

@@ -15,13 +15,13 @@ form of initializer was used.
 For example, the code above can be fixed to:
 
 ```
-enum Foo {
-    FirstValue(i32)
-}
+type U32 = u32;
+let t: U32 = 4;
+```
 
-fn main() {
-    let u = Foo::FirstValue(0i32);
+or:
 
-    let t = 4;
-}
+```
+struct U32 { value: u32 }
+let t = U32 { value: 4 };
 ```

compiler/rustc_hir/src/lang_items.rs

@@ -283,6 +283,7 @@ language_item_table! {
     // a weak lang item, but do not have it defined.
     Panic,                   sym::panic,               panic_fn,                   Target::Fn,             GenericRequirement::None;
     PanicFmt,                sym::panic_fmt,           panic_fmt,                  Target::Fn,             GenericRequirement::None;
+    PanicDisplay,            sym::panic_display,       panic_display,              Target::Fn,             GenericRequirement::None;
     PanicStr,                sym::panic_str,           panic_str,                  Target::Fn,             GenericRequirement::None;
     ConstPanicFmt,           sym::const_panic_fmt,     const_panic_fmt,            Target::Fn,             GenericRequirement::None;
     PanicBoundsCheck,        sym::panic_bounds_check,  panic_bounds_check_fn,      Target::Fn,             GenericRequirement::None;

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1334,30 +1334,25 @@ impl<'a> Parser<'a> {
     pub(super) fn recover_parens_around_for_head(
         &mut self,
         pat: P<Pat>,
-        expr: &Expr,
         begin_paren: Option<Span>,
     ) -> P<Pat> {
         match (&self.token.kind, begin_paren) {
             (token::CloseDelim(token::Paren), Some(begin_par_sp)) => {
                 self.bump();
 
-                let pat_str = self
-                    // Remove the `(` from the span of the pattern:
-                    .span_to_snippet(pat.span.trim_start(begin_par_sp).unwrap())
-                    .unwrap_or_else(|_| pprust::pat_to_string(&pat));
-
-                self.struct_span_err(self.prev_token.span, "unexpected closing `)`")
-                    .span_label(begin_par_sp, "opening `(`")
-                    .span_suggestion(
-                        begin_par_sp.to(self.prev_token.span),
-                        "remove parenthesis in `for` loop",
-                        format!("{} in {}", pat_str, pprust::expr_to_string(&expr)),
-                        // With e.g. `for (x) in y)` this would replace `(x) in y)`
-                        // with `x) in y)` which is syntactically invalid.
-                        // However, this is prevented before we get here.
-                        Applicability::MachineApplicable,
-                    )
-                    .emit();
+                self.struct_span_err(
+                    MultiSpan::from_spans(vec![begin_par_sp, self.prev_token.span]),
+                    "unexpected parenthesis surrounding `for` loop head",
+                )
+                .multipart_suggestion(
+                    "remove parenthesis in `for` loop",
+                    vec![(begin_par_sp, String::new()), (self.prev_token.span, String::new())],
+                    // With e.g. `for (x) in y)` this would replace `(x) in y)`
+                    // with `x) in y)` which is syntactically invalid.
+                    // However, this is prevented before we get here.
+                    Applicability::MachineApplicable,
+                )
+                .emit();
 
                 // Unwrap `(pat)` into `pat` to avoid the `unused_parens` lint.
                 pat.and_then(|pat| match pat.kind {
@@ -1955,7 +1950,19 @@ impl<'a> Parser<'a> {
         }
         match self.parse_expr_res(Restrictions::CONST_EXPR, None) {
             Ok(expr) => {
-                if token::Comma == self.token.kind || self.token.kind.should_end_const_arg() {
+                // Find a mistake like `MyTrait<Assoc == S::Assoc>`.
+                if token::EqEq == snapshot.token.kind {
+                    err.span_suggestion(
+                        snapshot.token.span,
+                        "if you meant to use an associated type binding, replace `==` with `=`",
+                        "=".to_string(),
+                        Applicability::MaybeIncorrect,
+                    );
+                    let value = self.mk_expr_err(start.to(expr.span));
+                    err.emit();
+                    return Ok(GenericArg::Const(AnonConst { id: ast::DUMMY_NODE_ID, value }));
+                } else if token::Comma == self.token.kind || self.token.kind.should_end_const_arg()
+                {
                     // Avoid the following output by checking that we consumed a full const arg:
                     // help: expressions must be enclosed in braces to be used as const generic
                     //       arguments

compiler/rustc_parse/src/parser/expr.rs

@@ -2042,7 +2042,7 @@ impl<'a> Parser<'a> {
         self.check_for_for_in_in_typo(self.prev_token.span);
         let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
 
-        let pat = self.recover_parens_around_for_head(pat, &expr, begin_paren);
+        let pat = self.recover_parens_around_for_head(pat, begin_paren);
 
         let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
         attrs.extend(iattrs);

compiler/rustc_passes/src/stability.rs

@@ -929,6 +929,16 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
     let declared_lib_features = &tcx.features().declared_lib_features;
     let mut remaining_lib_features = FxHashMap::default();
     for (feature, span) in declared_lib_features {
+        if !tcx.sess.opts.unstable_features.is_nightly_build() {
+            struct_span_err!(
+                tcx.sess,
+                *span,
+                E0554,
+                "`#![feature]` may not be used on the {} release channel",
+                env!("CFG_RELEASE_CHANNEL")
+            )
+            .emit();
+        }
         if remaining_lib_features.contains_key(&feature) {
             // Warn if the user enables a lib feature multiple times.
             duplicate_feature_err(tcx.sess, *span, *feature);