Auto merge of #60708 - Centril:rollup-j5smdo0, r=Centril

Rollup of 6 pull requests

Successful merges:

 - #60529 (RFC 2008: Uninhabitedness fixes for enum variants and tests)
 - #60620 (Fix a couple of FIXMEs in ext::tt::transcribe)
 - #60659 (Tweak `Symbol` and `InternedString`)
 - #60692 (Extend #60676 test for nested mut patterns.)
 - #60697 (add regression test for #60629)
 - #60701 (Update mailmap for mati865)

Failed merges:

r? @ghost

.mailmap

@@ -155,6 +155,8 @@ Mark Sinclair <[email protected]> =Mark Sinclair <[email protected]>
 Markus Westerlind <[email protected]> Markus <[email protected]>
 Martin Hafskjold Thoresen <[email protected]>
 Matej Lach <[email protected]> Matej Ľach <[email protected]>
+Mateusz Mikuła <[email protected]> <[email protected]>
+Mateusz Mikuła <[email protected]> <[email protected]>
 Matt Brubeck <[email protected]> <[email protected]>
 Matthew Auld <[email protected]>
 Matthew McPherrin <[email protected]> <[email protected]>

src/librustc/ty/inhabitedness/mod.rs

@@ -113,9 +113,14 @@ impl<'a, 'gcx, 'tcx> AdtDef {
  tcx: TyCtxt<'a, 'gcx, 'tcx>,
  substs: SubstsRef<'tcx>) -> DefIdForest
  {
- DefIdForest::intersection(tcx, self.variants.iter().map(|v| {
- v.uninhabited_from(tcx, substs, self.adt_kind())
- }))
+ // Non-exhaustive ADTs from other crates are always considered inhabited.
+ if self.is_variant_list_non_exhaustive() && !self.did.is_local() {
+ DefIdForest::empty()
+ } else {
+ DefIdForest::intersection(tcx, self.variants.iter().map(|v| {
+ v.uninhabited_from(tcx, substs, self.adt_kind())
+ }))
+ }
  }
 }
 
@@ -134,9 +139,14 @@ impl<'a, 'gcx, 'tcx> VariantDef {
  AdtKind::Enum => true,
  AdtKind::Struct => false,
  };
- DefIdForest::union(tcx, self.fields.iter().map(|f| {
- f.uninhabited_from(tcx, substs, is_enum)
- }))
+ // Non-exhaustive variants from other crates are always considered inhabited.
+ if self.is_field_list_non_exhaustive() && !self.def_id.is_local() {
+ DefIdForest::empty()
+ } else {
+ DefIdForest::union(tcx, self.fields.iter().map(|f| {
+ f.uninhabited_from(tcx, substs, is_enum)
+ }))
+ }
  }
 }
 

src/librustc_mir/hair/pattern/_match.rs

@@ -388,6 +388,18 @@ impl<'a, 'tcx> MatchCheckCtxt<'a, 'tcx> {
  }
  }
 
+ fn is_non_exhaustive_variant<'p>(&self, pattern: &'p Pattern<'tcx>) -> bool
+ where 'a: 'p
+ {
+ match *pattern.kind {
+ PatternKind::Variant { adt_def, variant_index, .. } => {
+ let ref variant = adt_def.variants[variant_index];
+ variant.is_field_list_non_exhaustive()
+ }
+ _ => false,
+ }
+ }
+
  fn is_non_exhaustive_enum(&self, ty: Ty<'tcx>) -> bool {
  match ty.sty {
  ty::Adt(adt_def, ..) => adt_def.is_variant_list_non_exhaustive(),
@@ -1097,10 +1109,17 @@ pub fn is_useful<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
  debug!("is_useful_expand_first_col: pcx={:#?}, expanding {:#?}", pcx, v[0]);
 
  if let Some(constructors) = pat_constructors(cx, v[0], pcx) {
- debug!("is_useful - expanding constructors: {:#?}", constructors);
- split_grouped_constructors(cx.tcx, constructors, matrix, pcx.ty).into_iter().map(|c|
- is_useful_specialized(cx, matrix, v, c, pcx.ty, witness)
- ).find(|result| result.is_useful()).unwrap_or(NotUseful)
+ let is_declared_nonexhaustive = cx.is_non_exhaustive_variant(v[0]) && !cx.is_local(pcx.ty);
+ debug!("is_useful - expanding constructors: {:#?}, is_declared_nonexhaustive: {:?}",
+ constructors, is_declared_nonexhaustive);
+
+ if is_declared_nonexhaustive {
+ Useful
+ } else {
+ split_grouped_constructors(cx.tcx, constructors, matrix, pcx.ty).into_iter().map(|c|
+ is_useful_specialized(cx, matrix, v, c, pcx.ty, witness)
+ ).find(|result| result.is_useful()).unwrap_or(NotUseful)
+ }
  } else {
  debug!("is_useful - expanding wildcard");
 

src/librustc_mir/hair/pattern/check_match.rs

@@ -208,7 +208,11 @@ impl<'a, 'tcx> MatchVisitor<'a, 'tcx> {
  .map(|variant| variant.ident)
  .collect();
  }
- def.variants.is_empty()
+
+ let is_non_exhaustive_and_non_local =
+ def.is_variant_list_non_exhaustive() && !def.did.is_local();
+
+ !(is_non_exhaustive_and_non_local) && def.variants.is_empty()
  },
  _ => false
  }

src/libsyntax/ext/tt/transcribe.rs

@@ -170,10 +170,9 @@ pub fn transcribe(
  }
 
  LockstepIterSize::Contradiction(ref msg) => {
- // FIXME: this should be impossible. I (mark-i-m) believe it would
- // represent a bug in the macro_parser.
- // FIXME #2887 blame macro invoker instead
- cx.span_fatal(seq.span(), &msg[..]);
+ // This should never happen because the macro parser should generate
+ // properly-sized matches for all meta-vars.
+ cx.span_bug(seq.span(), &msg[..]);
  }
 
  LockstepIterSize::Constraint(len, _) => {
@@ -188,14 +187,13 @@ pub fn transcribe(
  // Is the repetition empty?
  if len == 0 {
  if seq.op == quoted::KleeneOp::OneOrMore {
- // FIXME: this should be impossible because we check for this in
- // macro_parser.rs
- // FIXME #2887 blame invoker
- cx.span_fatal(sp.entire(), "this must repeat at least once");
+ // This should be impossible because the macro parser would not
+ // match the given macro arm.
+ cx.span_bug(sp.entire(), "this must repeat at least once");
  }
  } else {
  // 0 is the initial counter (we have done 0 repretitions so far). `len`
- //  is the total number of reptitions we should generate.
+ // is the total number of reptitions we should generate.
  repeats.push((0, len));
 
  // The first time we encounter the sequence we push it to the stack. It

src/libsyntax_pos/symbol.rs

@@ -344,9 +344,22 @@ impl Decodable for Ident {
  }
 }
 
-/// A symbol is an interned or gensymed string. The use of `newtype_index!` means
-/// that `Option<Symbol>` only takes up 4 bytes, because `newtype_index!` reserves
-/// the last 256 values for tagging purposes.
+/// A symbol is an interned or gensymed string. A gensym is a symbol that is
+/// never equal to any other symbol. E.g.:
+/// ```
+/// assert_eq!(Symbol::intern("x"), Symbol::intern("x"))
+/// assert_ne!(Symbol::gensym("x"), Symbol::intern("x"))
+/// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
+/// ```
+/// Conceptually, a gensym can be thought of as a normal symbol with an
+/// invisible unique suffix. Gensyms are useful when creating new identifiers
+/// that must not match any existing identifiers, e.g. during macro expansion
+/// and syntax desugaring.
+///
+/// Internally, a Symbol is implemented as an index, and all operations
+/// (including hashing, equality, and ordering) operate on that index. The use
+/// of `newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
+/// because `newtype_index!` reserves the last 256 values for tagging purposes.
 ///
 /// Note that `Symbol` cannot directly be a `newtype_index!` because it implements
 /// `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
@@ -367,10 +380,6 @@ impl Symbol {
  with_interner(|interner| interner.intern(string))
  }
 
- pub fn interned(self) -> Self {
- with_interner(|interner| interner.interned(self))
- }
-
  /// Gensyms a new `usize`, using the current interner.
  pub fn gensym(string: &str) -> Self {
  with_interner(|interner| interner.gensym(string))
@@ -380,6 +389,7 @@ impl Symbol {
  with_interner(|interner| interner.gensymed(self))
  }
 
+ // WARNING: this function is deprecated and will be removed in the future.
  pub fn is_gensymed(self) -> bool {
  with_interner(|interner| interner.is_gensymed(self))
  }
@@ -488,11 +498,11 @@ impl Interner {
  name
  }
 
- pub fn interned(&self, symbol: Symbol) -> Symbol {
+ fn interned(&self, symbol: Symbol) -> Symbol {
  if (symbol.0.as_usize()) < self.strings.len() {
  symbol
  } else {
- self.interned(self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize])
+ self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
  }
  }
 
@@ -510,10 +520,15 @@ impl Interner {
  symbol.0.as_usize() >= self.strings.len()
  }
 
+ // Get the symbol as a string. `Symbol::as_str()` should be used in
+ // preference to this function.
  pub fn get(&self, symbol: Symbol) -> &str {
  match self.strings.get(symbol.0.as_usize()) {
  Some(string) => string,
- None => self.get(self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]),
+ None => {
+ let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
+ self.strings[symbol.0.as_usize()]
+ }
  }
  }
 }
@@ -611,11 +626,17 @@ fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
  GLOBALS.with(|globals| f(&mut *globals.symbol_interner.lock()))
 }
 
-/// Represents a string stored in the interner. Because the interner outlives any thread
-/// which uses this type, we can safely treat `string` which points to interner data,
-/// as an immortal string, as long as this type never crosses between threads.
-// FIXME: ensure that the interner outlives any thread which uses `LocalInternedString`,
-// by creating a new thread right after constructing the interner.
+/// An alternative to `Symbol` and `InternedString`, useful when the chars
+/// within the symbol need to be accessed. It is best used for temporary
+/// values.
+///
+/// Because the interner outlives any thread which uses this type, we can
+/// safely treat `string` which points to interner data, as an immortal string,
+/// as long as this type never crosses between threads.
+//
+// FIXME: ensure that the interner outlives any thread which uses
+// `LocalInternedString`, by creating a new thread right after constructing the
+// interner.
 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
 pub struct LocalInternedString {
  string: &'static str,
@@ -708,7 +729,19 @@ impl Encodable for LocalInternedString {
  }
 }
 
-/// Represents a string stored in the string interner.
+/// An alternative to `Symbol` that is focused on string contents. It has two
+/// main differences to `Symbol`.
+///
+/// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
+/// string chars rather than the symbol integer. This is useful when hash
+/// stability is required across compile sessions, or a guaranteed sort
+/// ordering is required.
+///
+/// Second, gensym-ness is irrelevant. E.g.:
+/// ```
+/// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
+/// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
+/// ```
 #[derive(Clone, Copy, Eq)]
 pub struct InternedString {
  symbol: Symbol,
@@ -725,6 +758,15 @@ impl InternedString {
  unsafe { f(&*str) }
  }
 
+ fn with2<F: FnOnce(&str, &str) -> R, R>(self, other: &InternedString, f: F) -> R {
+ let (self_str, other_str) = with_interner(|interner| {
+ (interner.get(self.symbol) as *const str,
+ interner.get(other.symbol) as *const str)
+ });
+ // This is safe for the same reason that `with` is safe.
+ unsafe { f(&*self_str, &*other_str) }
+ }
+
  pub fn as_symbol(self) -> Symbol {
  self.symbol
  }
@@ -745,7 +787,7 @@ impl PartialOrd<InternedString> for InternedString {
  if self.symbol == other.symbol {
  return Some(Ordering::Equal);
  }
- self.with(|self_str| other.with(|other_str| self_str.partial_cmp(other_str)))
+ self.with2(other, |self_str, other_str| self_str.partial_cmp(other_str))
  }
 }
 
@@ -754,7 +796,7 @@ impl Ord for InternedString {
  if self.symbol == other.symbol {
  return Ordering::Equal;
  }
- self.with(|self_str| other.with(|other_str| self_str.cmp(&other_str)))
+ self.with2(other, |self_str, other_str| self_str.cmp(other_str))
  }
 }
 
@@ -794,12 +836,6 @@ impl<'a> PartialEq<InternedString> for &'a String {
  }
 }
 
-impl std::convert::From<InternedString> for String {
- fn from(val: InternedString) -> String {
- val.as_symbol().to_string()
- }
-}
-
 impl fmt::Debug for InternedString {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  self.with(|str| fmt::Debug::fmt(&str, f))

src/test/incremental/issue-60629.rs

@@ -0,0 +1,10 @@
+// revisions:rpass1 rpass2
+
+struct A;
+
+#[cfg(rpass2)]
+impl From<A> for () {
+ fn from(_: A) {}
+}
+
+fn main() {}

src/test/ui/async-await/issue-60674.rs

@@ -11,4 +11,10 @@ extern crate issue_60674;
 #[issue_60674::attr]
 async fn f(mut x: u8) {}
 
+#[issue_60674::attr]
+async fn g((mut x, y, mut z): (u8, u8, u8)) {}
+
+#[issue_60674::attr]
+async fn g(mut x: u8, (a, mut b, c): (u8, u8, u8), y: u8) {}
+
 fn main() {}

src/test/ui/async-await/issue-60674.stdout

@@ -1 +1,3 @@
 async fn f(mut x: u8) { }
+async fn g((mut x, y, mut z): (u8, u8, u8)) { }
+async fn g(mut x: u8, (a, mut b, c): (u8, u8, u8), y: u8) { }

src/test/ui/pattern/const-pat-ice.stderr

@@ -1,4 +1,4 @@
-thread 'rustc' panicked at 'assertion failed: rows.iter().all(|r| r.len() == v.len())', src/librustc_mir/hair/pattern/_match.rs:1071:5
+thread 'rustc' panicked at 'assertion failed: rows.iter().all(|r| r.len() == v.len())', src/librustc_mir/hair/pattern/_match.rs:1083:5
 note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
 
 error: internal compiler error: unexpected panic

src/test/ui/rfc-2008-non-exhaustive/uninhabited/auxiliary/uninhabited.rs

@@ -0,0 +1,33 @@
+#![crate_type = "rlib"]
+#![feature(never_type)]
+#![feature(non_exhaustive)]
+
+#[non_exhaustive]
+pub enum UninhabitedEnum {
+}
+
+#[non_exhaustive]
+pub struct UninhabitedStruct {
+ _priv: !,
+}
+
+#[non_exhaustive]
+pub struct UninhabitedTupleStruct(!);
+
+pub enum UninhabitedVariants {
+ #[non_exhaustive] Tuple(!),
+ #[non_exhaustive] Struct { x: ! }
+}
+
+pub enum PartiallyInhabitedVariants {
+ Tuple(u8),
+ #[non_exhaustive] Struct { x: ! }
+}
+
+pub struct IndirectUninhabitedEnum(UninhabitedEnum);
+
+pub struct IndirectUninhabitedStruct(UninhabitedStruct);
+
+pub struct IndirectUninhabitedTupleStruct(UninhabitedTupleStruct);
+
+pub struct IndirectUninhabitedVariants(UninhabitedVariants);