Auto merge of #87347 - GuillaumeGomez:rollup-ke92xxc, r=GuillaumeGomez

Rollup of 9 pull requests

Successful merges:

 - #87187 (Fix NixOS detection)
 - #87206 (avoid temporary vectors/reuse iterators)
 - #87230 (Fix docblock <table> overflow)
 - #87273 (Recognize bounds on impls as const bounds)
 - #87279 (Add comments explaining the unix command-line argument support.)
 - #87301 (Fix typo in compile.rs)
 - #87311 (Get back the more precise suggestion spans of old regionck)
 - #87321 (Add long explanation for E0722)
 - #87342 (Add long explanation for E0757)

Failed merges:

 - #87270 (Don't display <table> in item summary)

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

compiler/rustc_builtin_macros/src/deriving/generic/ty.rs

@@ -72,13 +72,9 @@ pub fn to_path(
     ) -> ast::Path {
         let mut idents = self.path.iter().map(|s| Ident::new(*s, span)).collect();
         let lt = mk_lifetimes(cx, span, &self.lifetime);
-        let tys: Vec<P<ast::Ty>> =
-            self.params.iter().map(|t| t.to_ty(cx, span, self_ty, self_generics)).collect();
-        let params = lt
-            .into_iter()
-            .map(GenericArg::Lifetime)
-            .chain(tys.into_iter().map(GenericArg::Type))
-            .collect();
+        let tys = self.params.iter().map(|t| t.to_ty(cx, span, self_ty, self_generics));
+        let params =
+            lt.into_iter().map(GenericArg::Lifetime).chain(tys.map(GenericArg::Type)).collect();
 
         match self.kind {
             PathKind::Global => cx.path_all(span, true, idents, params),

compiler/rustc_error_codes/src/error_codes.rs

@@ -418,6 +418,7 @@
 E0718: include_str!("./error_codes/E0718.md"),
 E0719: include_str!("./error_codes/E0719.md"),
 E0720: include_str!("./error_codes/E0720.md"),
+E0722: include_str!("./error_codes/E0722.md"),
 E0724: include_str!("./error_codes/E0724.md"),
 E0725: include_str!("./error_codes/E0725.md"),
 E0727: include_str!("./error_codes/E0727.md"),
@@ -449,6 +450,7 @@
 E0754: include_str!("./error_codes/E0754.md"),
 E0755: include_str!("./error_codes/E0755.md"),
 E0756: include_str!("./error_codes/E0756.md"),
+E0757: include_str!("./error_codes/E0757.md"),
 E0758: include_str!("./error_codes/E0758.md"),
 E0759: include_str!("./error_codes/E0759.md"),
 E0760: include_str!("./error_codes/E0760.md"),
@@ -634,10 +636,8 @@
     E0711, // a feature has been declared with conflicting stability attributes
     E0717, // rustc_promotable without stability attribute
 //  E0721, // `await` keyword
-    E0722, // Malformed `#[optimize]` attribute
 //    E0723, unstable feature in `const` context
     E0726, // non-explicit (not `'_`) elided lifetime in unsupported position
 //  E0738, // Removed; errored on `#[track_caller] fn`s in `extern "Rust" { ... }`.
-    E0757, // `#[ffi_const]` functions cannot be `#[ffi_pure]`
     E0772, // `'static' obligation coming from `impl dyn Trait {}` or `impl Foo for dyn Bar {}`.
 }

compiler/rustc_error_codes/src/error_codes/E0722.md

@@ -0,0 +1,31 @@
+The `optimize` attribute was malformed.
+
+Erroneous code example:
+
+```compile_fail,E0722
+#![feature(optimize_attribute)]
+
+#[optimize(something)] // error: invalid argument
+pub fn something() {}
+```
+
+The `#[optimize]` attribute should be used as follows:
+
+- `#[optimize(size)]` -- instructs the optimization pipeline to generate code
+  that's smaller rather than faster
+
+- `#[optimize(speed)]` -- instructs the optimization pipeline to generate code
+  that's faster rather than smaller
+
+For example:
+
+```
+#![feature(optimize_attribute)]
+
+#[optimize(size)]
+pub fn something() {}
+```
+
+See [RFC 2412] for more details.
+
+[RFC 2412]: https://rust-lang.github.io/rfcs/2412-optimize-attr.html

compiler/rustc_error_codes/src/error_codes/E0757.md

@@ -0,0 +1,33 @@
+A function was given both the `ffi_const` and `ffi_pure` attributes.
+
+Erroneous code example:
+
+```compile_fail,E0757
+#![feature(ffi_const, ffi_pure)]
+
+extern "C" {
+    #[ffi_const]
+    #[ffi_pure] // error: `#[ffi_const]` function cannot be `#[ffi_pure]`
+    pub fn square(num: i32) -> i32;
+}
+```
+
+As `ffi_const` provides stronger guarantees than `ffi_pure`, remove the
+`ffi_pure` attribute:
+
+```
+#![feature(ffi_const)]
+
+extern "C" {
+    #[ffi_const]
+    pub fn square(num: i32) -> i32;
+}
+```
+
+You can get more information about `const` and `pure` in the [GCC documentation
+on Common Function Attributes]. The unstable Rust Book has more information
+about [`ffi_const`] and [`ffi_pure`].
+
+[GCC documentation on Common Function Attributes]: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
+[`ffi_const`]: https://doc.rust-lang.org/nightly/unstable-book/language-features/ffi-const.html
+[`ffi_pure`]: https://doc.rust-lang.org/nightly/unstable-book/language-features/ffi-pure.html

compiler/rustc_hir/src/hir.rs

@@ -3060,6 +3060,27 @@ pub fn hir_id(&self) -> Option<HirId> {
             Node::Crate(_) | Node::Visibility(_) => None,
         }
     }
+
+    /// Returns `Constness::Const` when this node is a const fn/impl.
+    pub fn constness(&self) -> Constness {
+        match self {
+            Node::Item(Item {
+                kind: ItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..),
+                ..
+            })
+            | Node::TraitItem(TraitItem {
+                kind: TraitItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..),
+                ..
+            })
+            | Node::ImplItem(ImplItem {
+                kind: ImplItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..),
+                ..
+            })
+            | Node::Item(Item { kind: ItemKind::Impl(Impl { constness, .. }), .. }) => *constness,
+
+            _ => Constness::NotConst,
+        }
+    }
 }
 
 // Some nodes are used a lot. Make sure they don't unintentionally get bigger.

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2130,7 +2130,7 @@ pub fn construct_generic_bound_failure(
         let new_lt = generics
             .as_ref()
             .and_then(|(parent_g, g)| {
-                let possible: Vec<_> = (b'a'..=b'z').map(|c| format!("'{}", c as char)).collect();
+                let mut possible = (b'a'..=b'z').map(|c| format!("'{}", c as char));
                 let mut lts_names = g
                     .params
                     .iter()
@@ -2146,7 +2146,7 @@ pub fn construct_generic_bound_failure(
                     );
                 }
                 let lts = lts_names.iter().map(|s| -> &str { &*s }).collect::<Vec<_>>();
-                possible.into_iter().find(|candidate| !lts.contains(&candidate.as_str()))
+                possible.find(|candidate| !lts.contains(&candidate.as_str()))
             })
             .unwrap_or("'lt".to_string());
         let add_lt_sugg = generics

compiler/rustc_mir/src/borrow_check/diagnostics/region_errors.rs

@@ -9,7 +9,7 @@
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::{self, RegionVid, Ty};
 use rustc_span::symbol::{kw, sym};
-use rustc_span::Span;
+use rustc_span::{BytePos, Span};
 
 use crate::util::borrowck_errors;
 
@@ -641,12 +641,14 @@ fn add_static_impl_trait_suggestion(
                         } else {
                             "'_".to_string()
                         };
-                        let suggestion = if snippet.ends_with(';') {
+                        let span = if snippet.ends_with(';') {
                             // `type X = impl Trait;`
-                            format!("{} + {};", &snippet[..snippet.len() - 1], suggestable_fr_name)
+                            span.with_hi(span.hi() - BytePos(1))
                         } else {
-                            format!("{} + {}", snippet, suggestable_fr_name)
+                            span
                         };
+                        let suggestion = format!(" + {}", suggestable_fr_name);
+                        let span = span.shrink_to_hi();
                         diag.span_suggestion(
                             span,
                             &format!(

compiler/rustc_mir/src/transform/check_consts/validation.rs

@@ -897,6 +897,8 @@ fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location
                                 permitted = true;
                             }
                         }
+                        if !permitted {
+                            // if trait's impls are all const, permit the call.
                             let mut const_impls = true;
                             tcx.for_each_relevant_impl(trait_id, substs.type_at(0), |imp| {
                                 if const_impls {
@@ -909,6 +911,7 @@ fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location
                                 permitted = true;
                             }
                         }
+                    }
 
                     if !permitted {
                         self.check_op(ops::FnCallNonConst);

compiler/rustc_typeck/src/check/fn_ctxt/mod.rs

@@ -15,7 +15,6 @@
 use rustc_infer::infer;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
-use rustc_middle::hir::map::blocks::FnLikeNode;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::{self, Const, Ty, TyCtxt};
@@ -175,13 +174,7 @@ fn item_def_id(&self) -> Option<DefId> {
     }
 
     fn default_constness_for_trait_bounds(&self) -> hir::Constness {
-        // FIXME: refactor this into a method
-        let node = self.tcx.hir().get(self.body_id);
-        if let Some(fn_like) = FnLikeNode::from_node(node) {
-            fn_like.constness()
-        } else {
-            hir::Constness::NotConst
-        }
+        self.tcx.hir().get(self.body_id).constness()
     }
 
     fn get_type_parameter_bounds(

compiler/rustc_typeck/src/collect.rs

@@ -35,7 +35,6 @@
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::weak_lang_items;
 use rustc_hir::{GenericParamKind, HirId, Node};
-use rustc_middle::hir::map::blocks::FnLikeNode;
 use rustc_middle::hir::map::Map;
 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc_middle::mir::mono::Linkage;
@@ -358,11 +357,7 @@ fn item_def_id(&self) -> Option<DefId> {
     }
 
     fn default_constness_for_trait_bounds(&self) -> hir::Constness {
-        if let Some(fn_like) = FnLikeNode::from_node(self.node()) {
-            fn_like.constness()
-        } else {
-            hir::Constness::NotConst
-        }
+        self.node().constness()
     }
 
     fn get_type_parameter_bounds(

library/std/src/sys/unix/args.rs

@@ -77,10 +77,18 @@ mod imp {
     use crate::ptr;
     use crate::sync::atomic::{AtomicIsize, AtomicPtr, Ordering};
 
+    // The system-provided argc and argv, which we store in static memory
+    // here so that we can defer the work of parsing them until its actually
+    // needed.
+    //
+    // Note that we never mutate argv/argc, the argv array, or the argv
+    // strings, which allows the code in this file to be very simple.
     static ARGC: AtomicIsize = AtomicIsize::new(0);
     static ARGV: AtomicPtr<*const u8> = AtomicPtr::new(ptr::null_mut());
 
     unsafe fn really_init(argc: isize, argv: *const *const u8) {
+        // These don't need to be ordered with each other or other stores,
+        // because they only hold the unmodified system-provide argv/argc.
         ARGC.store(argc, Ordering::Relaxed);
         ARGV.store(argv as *mut _, Ordering::Relaxed);
     }
@@ -122,8 +130,14 @@ pub fn args() -> Args {
 
     fn clone() -> Vec<OsString> {
         unsafe {
-            // Load ARGC and ARGV without a lock. If the store to either ARGV or
-            // ARGC isn't visible yet, we'll return an empty argument list.
+            // Load ARGC and ARGV, which hold the unmodified system-provided
+            // argc/argv, so we can read the pointed-to memory without atomics
+            // or synchronization.
+            //
+            // If either ARGC or ARGV is still zero or null, then either there
+            // really are no arguments, or someone is asking for `args()`
+            // before initialization has completed, and we return an empty
+            // list.
             let argv = ARGV.load(Ordering::Relaxed);
             let argc = if argv.is_null() { 0 } else { ARGC.load(Ordering::Relaxed) };
             (0..argc)

src/bootstrap/bootstrap.py

@@ -580,7 +580,13 @@ class RustBuild(object):
         if ostype != "Linux":
             return
 
-        if not os.path.exists("/etc/NIXOS"):
+        # Use `/etc/os-release` instead of `/etc/NIXOS`.
+        # The latter one does not exist on NixOS when using tmpfs as root.
+        try:
+            with open("/etc/os-release", "r") as f:
+                if not any(line.strip() == "ID=nixos" for line in f):
+                    return
+        except FileNotFoundError:
             return
         if os.path.exists("/lib"):
             return

src/bootstrap/compile.rs

@@ -2,7 +2,7 @@
 //! library.
 //!
 //! This module contains some of the real meat in the rustbuild build system
-//! which is where Cargo is used to compiler the standard library, libtest, and
+//! which is where Cargo is used to compile the standard library, libtest, and
 //! compiler. This module is also responsible for assembling the sysroot as it
 //! goes along from the output of the previous stage.
 

src/librustdoc/html/static/css/rustdoc.css

@@ -560,7 +560,8 @@ nav.sub {
 .docblock table {
 	margin: .5em 0;
 	width: calc(100% - 2px);
-	border: 1px dashed;
+	overflow-x: auto;
+	display: block;
 }
 
 .docblock table td {

src/librustdoc/html/static/css/themes/ayu.css

@@ -140,7 +140,7 @@ pre, .rustdoc.source .example-wrap {
 	border-bottom-color: #5c6773;
 }
 
-.docblock table, .docblock table td, .docblock table th {
+.docblock table td, .docblock table th {
 	border-color: #5c6773;
 }
 

src/librustdoc/html/static/css/themes/dark.css

@@ -97,7 +97,7 @@ pre, .rustdoc.source .example-wrap {
 	border-bottom-color: #DDD;
 }
 
-.docblock table, .docblock table td, .docblock table th {
+.docblock table td, .docblock table th {
 	border-color: #ddd;
 }
 

src/librustdoc/html/static/css/themes/light.css

@@ -97,7 +97,7 @@ pre, .rustdoc.source .example-wrap {
 	border-bottom-color: #ddd;
 }
 
-.docblock table, .docblock table td, .docblock table th {
+.docblock table td, .docblock table th {
 	border-color: #ddd;
 }
 

src/test/rustdoc-gui/docblock-table-overflow.goml

@@ -0,0 +1,9 @@
+// This test ensures that the type declaration content overflow is handled inside the <pre> directly.
+goto: file://|DOC_PATH|/lib2/long_table/struct.Foo.html
+// We set a fixed size so there is no chance of "random" resize.
+size: (1100, 800)
+// Logically, the ".docblock" and the "<p>" should have the same scroll width.
+compare-elements-property: (".top-doc .docblock", ".top-doc .docblock > p", ["scrollWidth"])
+assert-property: (".top-doc .docblock", {"scrollWidth": "816"})
+// However, since there is overflow in the <table>, its scroll width is bigger.
+assert-property: (".top-doc .docblock table", {"scrollWidth": "1573"})

src/test/rustdoc-gui/src/lib2/lib.rs

@@ -57,3 +57,12 @@ pub mod long_trait {
     pub trait ALongNameBecauseItHelpsTestingTheCurrentProblem: DerefMut<Target = u32>
         + From<u128> + Send + Sync + AsRef<str> + 'static {}
 }
+
+pub mod long_table {
+    /// | This::is::a::kinda::very::long::header::number::one | This::is::a::kinda::very::long::header::number::two | This::is::a::kinda::very::long::header::number::one | This::is::a::kinda::very::long::header::number::two |
+    /// | ----------- | ----------- | ----------- | ----------- |
+    /// | This::is::a::kinda::long::content::number::one | This::is::a::kinda::very::long::content::number::two | This::is::a::kinda::long::content::number::one | This::is::a::kinda::very::long::content::number::two |
+    ///
+    /// I wanna sqdkfnqds f dsqf qds f dsqf dsq f dsq f qds f qds f qds f dsqq f dsf sqdf dsq fds f dsq f dq f ds fq sd fqds f dsq f sqd fsq df sd fdsqfqsd fdsq f dsq f dsqfd s dfq
+    pub struct Foo;
+}

src/test/rustdoc-gui/src/lib2/src/lib.rs

@@ -1,7 +0,0 @@
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
-    }
-}

src/test/ui/feature-gates/feature-gate-optimize_attribute.stderr

@@ -51,4 +51,5 @@ LL | #[optimize(banana)]
 
 error: aborting due to 6 previous errors
 
-For more information about this error, try `rustc --explain E0658`.
+Some errors have detailed explanations: E0658, E0722.
+For more information about an error, try `rustc --explain E0658`.

src/test/ui/ffi_const2.stderr

@@ -6,3 +6,4 @@ LL |     #[ffi_pure]
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0757`.

src/test/ui/impl-trait/must_outlive_least_region_or_bound.nll.stderr

@@ -9,7 +9,7 @@ LL | fn elided(x: &i32) -> impl Copy { x }
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'1`, add `'_` as a bound
    |
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
-   |                       ^^^^^^^^^^^^^^
+   |                                 ^^^^
 
 error: lifetime may not live long enough
   --> $DIR/must_outlive_least_region_or_bound.rs:5:32
@@ -23,7 +23,7 @@ LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'a`, add `'a` as a bound
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
-   |                                ^^^^^^^^^^^^^^
+   |                                          ^^^^
 
 error: lifetime may not live long enough
   --> $DIR/must_outlive_least_region_or_bound.rs:7:46

src/test/ui/impl-trait/static-return-lifetime-infered.nll.stderr

@@ -9,7 +9,7 @@ LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'1`, add `'_` as a bound
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
-   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                                           ^^^^
 
 error: lifetime may not live long enough
   --> $DIR/static-return-lifetime-infered.rs:9:37
@@ -23,7 +23,7 @@ LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'a`, add `'a` as a bound
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
-   |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                                             ^^^^
 
 error: aborting due to 2 previous errors
 

src/test/ui/rfc-2632-const-trait-impl/call-generic-in-impl.rs

@@ -0,0 +1,15 @@
+// check-pass
+#![feature(const_fn_trait_bound)]
+#![feature(const_trait_impl)]
+
+trait MyPartialEq {
+    fn eq(&self, other: &Self) -> bool;
+}
+
+impl<T: PartialEq> const MyPartialEq for T {
+    fn eq(&self, other: &Self) -> bool {
+        PartialEq::eq(self, other)
+    }
+}
+
+fn main() {}

src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.nll.stderr

@@ -9,7 +9,7 @@ LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'1`, add `'_` as a bound
    |
 LL |     async fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
-   |                                     ^^^^^^^^^^^^^^^
+   |                                                ^^^^
 
 error: aborting due to previous error
 

src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.nll.stderr

@@ -9,7 +9,7 @@ LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'1`, add `'_` as a bound
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
-   |                               ^^^^^^^^^^^^^^^
+   |                                          ^^^^
 
 error: aborting due to previous error
 

src/test/ui/suggestions/lifetimes/trait-object-nested-in-impl-trait.nll.stderr

@@ -9,7 +9,7 @@ LL |     fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> {
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'1`, add `'_` as a bound
    |
 LL |     fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> + '_ {
-   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                                          ^^^^
 
 error: lifetime may not live long enough
   --> $DIR/trait-object-nested-in-impl-trait.rs:39:9
@@ -47,7 +47,7 @@ LL |     fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> {
 help: to allow this `impl Trait` to capture borrowed data with lifetime `'a`, add `'a` as a bound
    |
 LL |     fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> + 'a {
-   |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                                                 ^^^^
 
 error: aborting due to 4 previous errors