Auto merge of #78528 - jonas-schievink:rollup-e70g9zk, r=jonas-schievink

Rollup of 11 pull requests

Successful merges:

 - #75078 (Improve documentation for slice strip_* functions)
 - #76138 (Explain fully qualified syntax for `Rc` and `Arc`)
 - #78244 (Dogfood {exclusive,half-open} ranges in compiler (nfc))
 - #78422 (Do not ICE on invalid input)
 - #78423 (rustc_span: improve bounds checks in byte_pos_to_line_and_col)
 - #78431 (Prefer new associated numeric consts in float error messages)
 - #78462 (Use unwrapDIPtr because the Scope may be null.)
 - #78493 (Update cargo)
 - #78499 (Prevent String::retain from creating non-utf8 strings when abusing panic)
 - #78505 (Update Clippy - temporary_cstring_as_ptr deprecation)
 - #78527 (Fix some more typos)

Failed merges:

r? `@ghost`

compiler/rustc_ast_lowering/src/lib.rs

@@ -148,7 +148,7 @@ struct LoweringContext<'a, 'hir: 'a> {
     is_collecting_in_band_lifetimes: bool,
 
     /// Currently in-scope lifetimes defined in impl headers, fn headers, or HRTB.
-    /// When `is_collectin_in_band_lifetimes` is true, each lifetime is checked
+    /// When `is_collecting_in_band_lifetimes` is true, each lifetime is checked
     /// against this list to see if it is already in-scope, or if a definition
     /// needs to be created for it.
     ///
@@ -257,7 +257,7 @@ enum ImplTraitPosition {
     /// Disallowed in `let` / `const` / `static` bindings.
     Binding,
 
-    /// All other posiitons.
+    /// All other positions.
     Other,
 }
 
@@ -363,7 +363,7 @@ enum ParenthesizedGenericArgs {
 ///   elided bounds follow special rules. Note that this only covers
 ///   cases where *nothing* is written; the `'_` in `Box<dyn Foo +
 ///   '_>` is a case of "modern" elision.
-/// - **Deprecated** -- this coverse cases like `Ref<T>`, where the lifetime
+/// - **Deprecated** -- this covers cases like `Ref<T>`, where the lifetime
 ///   parameter to ref is completely elided. `Ref<'_, T>` would be the modern,
 ///   non-deprecated equivalent.
 ///

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -516,7 +516,7 @@ impl<'a> AstValidator<'a> {
         self.session.source_map().guess_head_span(self.extern_mod.unwrap().span)
     }
 
-    /// An `fn` in `extern { ... }` cannot have qualfiers, e.g. `async fn`.
+    /// An `fn` in `extern { ... }` cannot have qualifiers, e.g. `async fn`.
     fn check_foreign_fn_headerless(&self, ident: Ident, span: Span, header: FnHeader) {
         if header.has_qualifiers() {
             self.err_handler()

compiler/rustc_data_structures/src/tagged_ptr.rs

@@ -24,7 +24,7 @@ mod drop;
 pub use copy::CopyTaggedPtr;
 pub use drop::TaggedPtr;
 
-/// This describes the pointer type encaspulated by TaggedPtr.
+/// This describes the pointer type encapsulated by TaggedPtr.
 ///
 /// # Safety
 ///

compiler/rustc_data_structures/src/transitive_relation.rs

@@ -18,7 +18,7 @@ pub struct TransitiveRelation<T: Eq + Hash> {
     edges: Vec<Edge>,
 
     // This is a cached transitive closure derived from the edges.
-    // Currently, we build it lazilly and just throw out any existing
+    // Currently, we build it lazily and just throw out any existing
     // copy whenever a new edge is added. (The Lock is to permit
     // the lazy computation.) This is kind of silly, except for the
     // fact its size is tied to `self.elements.len()`, so I wanted to
@@ -255,7 +255,7 @@ impl<T: Clone + Debug + Eq + Hash> TransitiveRelation<T> {
             // argument is that, after step 2, we know that no element
             // can reach its successors (in the vector, not the graph).
             // After step 3, we know that no element can reach any of
-            // its predecesssors (because of step 2) nor successors
+            // its predecessors (because of step 2) nor successors
             // (because we just called `pare_down`)
             //
             // This same algorithm is used in `parents` below.

compiler/rustc_errors/src/emitter.rs

@@ -513,7 +513,7 @@ impl Emitter for SilentEmitter {
 /// Maximum number of lines we will print for a multiline suggestion; arbitrary.
 ///
 /// This should be replaced with a more involved mechanism to output multiline suggestions that
-/// more closely mimmics the regular diagnostic output, where irrelevant code lines are elided.
+/// more closely mimics the regular diagnostic output, where irrelevant code lines are elided.
 pub const MAX_SUGGESTION_HIGHLIGHT_LINES: usize = 6;
 /// Maximum number of suggestions to be shown
 ///
@@ -887,7 +887,7 @@ impl EmitterWriter {
                                                      // or the next are vertical line placeholders.
                         || (annotation.takes_space() // If either this or the next annotation is
                             && next.has_label())     // multiline start/end, move it to a new line
-                        || (annotation.has_label()   // so as not to overlap the orizontal lines.
+                        || (annotation.has_label()   // so as not to overlap the horizontal lines.
                             && next.takes_space())
                         || (annotation.takes_space() && next.takes_space())
                         || (overlaps(next, annotation, l)

compiler/rustc_lint/src/lib.rs

@@ -35,6 +35,8 @@
 #![feature(never_type)]
 #![feature(nll)]
 #![feature(or_patterns)]
+#![feature(half_open_range_patterns)]
+#![feature(exclusive_range_pattern)]
 #![recursion_limit = "256"]
 
 #[macro_use]

compiler/rustc_lint/src/types.rs

@@ -439,7 +439,7 @@ fn lint_literal<'tcx>(
                 cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| {
                     lint.build(&format!("literal out of range for `{}`", t.name_str()))
                         .note(&format!(
-                            "the literal `{}` does not fit into the type `{}` and will be converted to `std::{}::INFINITY`",
+                            "the literal `{}` does not fit into the type `{}` and will be converted to `{}::INFINITY`",
                             cx.sess()
                                 .source_map()
                                 .span_to_snippet(lit.span)

compiler/rustc_lint/src/unused.rs

@@ -250,13 +250,13 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                     has_emitted
                 }
                 ty::Array(ty, len) => match len.try_eval_usize(cx.tcx, cx.param_env) {
+                    // If the array is empty we don't lint, to avoid false positives
+                    Some(0) | None => false,
                     // If the array is definitely non-empty, we can do `#[must_use]` checking.
-                    Some(n) if n != 0 => {
+                    Some(n) => {
                         let descr_pre = &format!("{}array{} of ", descr_pre, plural_suffix,);
                         check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, n as usize + 1)
                     }
-                    // Otherwise, we don't lint, to avoid false positives.
-                    _ => false,
                 },
                 ty::Closure(..) => {
                     cx.struct_span_lint(UNUSED_MUST_USE, span, |lint| {

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -766,7 +766,7 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateTypedef(
     LLVMMetadataRef File, unsigned LineNo, LLVMMetadataRef Scope) {
   return wrap(Builder->createTypedef(
     unwrap<DIType>(Type), StringRef(Name, NameLen), unwrap<DIFile>(File),
-    LineNo, unwrap<DIScope>(Scope)));
+    LineNo, unwrapDIPtr<DIScope>(Scope)));
 }
 
 extern "C" LLVMMetadataRef LLVMRustDIBuilderCreatePointerType(

compiler/rustc_middle/src/lib.rs

@@ -47,6 +47,8 @@
 #![feature(associated_type_bounds)]
 #![feature(rustc_attrs)]
 #![feature(int_error_matching)]
+#![feature(half_open_range_patterns)]
+#![feature(exclusive_range_pattern)]
 #![recursion_limit = "512"]
 
 #[macro_use]

compiler/rustc_middle/src/ty/inhabitedness/mod.rs

@@ -201,13 +201,13 @@ impl<'tcx> TyS<'tcx> {
             ),
 
             Array(ty, len) => match len.try_eval_usize(tcx, param_env) {
+                Some(0) | None => DefIdForest::empty(),
                 // If the array is definitely non-empty, it's uninhabited if
                 // the type of its elements is uninhabited.
-                Some(n) if n != 0 => ty.uninhabited_from(tcx, param_env),
-                _ => DefIdForest::empty(),
+                Some(1..) => ty.uninhabited_from(tcx, param_env),
             },
 
-            // References to uninitialised memory is valid for any type, including
+            // References to uninitialised memory are valid for any type, including
             // uninhabited types, in unsafe code, so we treat all references as
             // inhabited.
             // The precise semantics of inhabitedness with respect to references is currently

compiler/rustc_middle/src/ty/sty.rs

@@ -1834,10 +1834,10 @@ impl<'tcx> TyS<'tcx> {
             }
             ty::Array(ty, len) => {
                 match len.try_eval_usize(tcx, ParamEnv::empty()) {
+                    Some(0) | None => false,
                     // If the array is definitely non-empty, it's uninhabited if
                     // the type of its elements is uninhabited.
-                    Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx),
-                    _ => false,
+                    Some(1..) => ty.conservative_is_privately_uninhabited(tcx),
                 }
             }
             ty::Ref(..) => {

compiler/rustc_session/src/filesearch.rs

@@ -153,14 +153,14 @@ fn find_libdir(sysroot: &Path) -> Cow<'static, str> {
     const SECONDARY_LIB_DIR: &str = "lib";
 
     match option_env!("CFG_LIBDIR_RELATIVE") {
-        Some(libdir) if libdir != "lib" => libdir.into(),
-        _ => {
+        None | Some("lib") => {
             if sysroot.join(PRIMARY_LIB_DIR).join(RUST_LIB_DIR).exists() {
                 PRIMARY_LIB_DIR.into()
             } else {
                 SECONDARY_LIB_DIR.into()
             }
         }
+        Some(libdir) => libdir.into(),
     }
 }
 

compiler/rustc_span/src/caching_source_map_view.rs

@@ -1,13 +1,25 @@
 use crate::source_map::SourceMap;
 use crate::{BytePos, SourceFile};
 use rustc_data_structures::sync::Lrc;
+use std::ops::Range;
 
 #[derive(Clone)]
 struct CacheEntry {
     time_stamp: usize,
     line_number: usize,
-    line_start: BytePos,
-    line_end: BytePos,
+    // The line's byte position range in the `SourceMap`. This range will fail to contain a valid
+    // position in certain edge cases. Spans often start/end one past something, and when that
+    // something is the last character of a file (this can happen when a file doesn't end in a
+    // newline, for example), we'd still like for the position to be considered within the last
+    // line. However, it isn't according to the exclusive upper bound of this range. We cannot
+    // change the upper bound to be inclusive, because for most lines, the upper bound is the same
+    // as the lower bound of the next line, so there would be an ambiguity.
+    //
+    // Since the containment aspect of this range is only used to see whether or not the cache
+    // entry contains a position, the only ramification of the above is that we will get cache
+    // misses for these rare positions. A line lookup for the position via `SourceMap::lookup_line`
+    // after a cache miss will produce the last line number, as desired.
+    line: Range<BytePos>,
     file: Lrc<SourceFile>,
     file_index: usize,
 }
@@ -26,8 +38,7 @@ impl<'sm> CachingSourceMapView<'sm> {
         let entry = CacheEntry {
             time_stamp: 0,
             line_number: 0,
-            line_start: BytePos(0),
-            line_end: BytePos(0),
+            line: BytePos(0)..BytePos(0),
             file: first_file,
             file_index: 0,
         };
@@ -47,13 +58,13 @@ impl<'sm> CachingSourceMapView<'sm> {
 
         // Check if the position is in one of the cached lines
         for cache_entry in self.line_cache.iter_mut() {
-            if pos >= cache_entry.line_start && pos < cache_entry.line_end {
+            if cache_entry.line.contains(&pos) {
                 cache_entry.time_stamp = self.time_stamp;
 
                 return Some((
                     cache_entry.file.clone(),
                     cache_entry.line_number,
-                    pos - cache_entry.line_start,
+                    pos - cache_entry.line.start,
                 ));
             }
         }
@@ -69,13 +80,13 @@ impl<'sm> CachingSourceMapView<'sm> {
         let cache_entry = &mut self.line_cache[oldest];
 
         // If the entry doesn't point to the correct file, fix it up
-        if pos < cache_entry.file.start_pos || pos >= cache_entry.file.end_pos {
+        if !file_contains(&cache_entry.file, pos) {
             let file_valid;
             if self.source_map.files().len() > 0 {
                 let file_index = self.source_map.lookup_source_file_idx(pos);
                 let file = self.source_map.files()[file_index].clone();
 
-                if pos >= file.start_pos && pos < file.end_pos {
+                if file_contains(&file, pos) {
                     cache_entry.file = file;
                     cache_entry.file_index = file_index;
                     file_valid = true;
@@ -95,10 +106,19 @@ impl<'sm> CachingSourceMapView<'sm> {
         let line_bounds = cache_entry.file.line_bounds(line_index);
 
         cache_entry.line_number = line_index + 1;
-        cache_entry.line_start = line_bounds.0;
-        cache_entry.line_end = line_bounds.1;
+        cache_entry.line = line_bounds;
         cache_entry.time_stamp = self.time_stamp;
 
-        Some((cache_entry.file.clone(), cache_entry.line_number, pos - cache_entry.line_start))
+        Some((cache_entry.file.clone(), cache_entry.line_number, pos - cache_entry.line.start))
     }
 }
+
+#[inline]
+fn file_contains(file: &SourceFile, pos: BytePos) -> bool {
+    // `SourceMap::lookup_source_file_idx` and `SourceFile::contains` both consider the position
+    // one past the end of a file to belong to it. Normally, that's what we want. But for the
+    // purposes of converting a byte position to a line and column number, we can't come up with a
+    // line and column number if the file is empty, because an empty file doesn't contain any
+    // lines. So for our purposes, we don't consider empty files to contain any byte position.
+    file.contains(pos) && !file.is_empty()
+}

compiler/rustc_span/src/lib.rs

@@ -52,7 +52,7 @@ use std::cell::RefCell;
 use std::cmp::{self, Ordering};
 use std::fmt;
 use std::hash::Hash;
-use std::ops::{Add, Sub};
+use std::ops::{Add, Range, Sub};
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 
@@ -1426,24 +1426,33 @@ impl SourceFile {
         if line_index >= 0 { Some(line_index as usize) } else { None }
     }
 
-    pub fn line_bounds(&self, line_index: usize) -> (BytePos, BytePos) {
-        if self.start_pos == self.end_pos {
-            return (self.start_pos, self.end_pos);
+    pub fn line_bounds(&self, line_index: usize) -> Range<BytePos> {
+        if self.is_empty() {
+            return self.start_pos..self.end_pos;
         }
 
         assert!(line_index < self.lines.len());
         if line_index == (self.lines.len() - 1) {
-            (self.lines[line_index], self.end_pos)
+            self.lines[line_index]..self.end_pos
         } else {
-            (self.lines[line_index], self.lines[line_index + 1])
+            self.lines[line_index]..self.lines[line_index + 1]
         }
     }
 
+    /// Returns whether or not the file contains the given `SourceMap` byte
+    /// position. The position one past the end of the file is considered to be
+    /// contained by the file. This implies that files for which `is_empty`
+    /// returns true still contain one byte position according to this function.
     #[inline]
     pub fn contains(&self, byte_pos: BytePos) -> bool {
         byte_pos >= self.start_pos && byte_pos <= self.end_pos
     }
 
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.start_pos == self.end_pos
+    }
+
     /// Calculates the original byte position relative to the start of the file
     /// based on the given byte position.
     pub fn original_relative_byte_pos(&self, pos: BytePos) -> BytePos {

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -461,10 +461,17 @@ fn virtual_call_violation_for_method<'tcx>(
 
             let param_env = tcx.param_env(method.def_id);
 
-            let abi_of_ty = |ty: Ty<'tcx>| -> &Abi {
+            let abi_of_ty = |ty: Ty<'tcx>| -> Option<&Abi> {
                 match tcx.layout_of(param_env.and(ty)) {
-                    Ok(layout) => &layout.abi,
-                    Err(err) => bug!("error: {}\n while computing layout for type {:?}", err, ty),
+                    Ok(layout) => Some(&layout.abi),
+                    Err(err) => {
+                        // #78372
+                        tcx.sess.delay_span_bug(
+                            tcx.def_span(method.def_id),
+                            &format!("error: {}\n while computing layout for type {:?}", err, ty),
+                        );
+                        None
+                    }
                 }
             };
 
@@ -473,7 +480,7 @@ fn virtual_call_violation_for_method<'tcx>(
                 receiver_for_self_ty(tcx, receiver_ty, tcx.mk_unit(), method.def_id);
 
             match abi_of_ty(unit_receiver_ty) {
-                &Abi::Scalar(..) => (),
+                Some(Abi::Scalar(..)) => (),
                 abi => {
                     tcx.sess.delay_span_bug(
                         tcx.def_span(method.def_id),
@@ -493,13 +500,12 @@ fn virtual_call_violation_for_method<'tcx>(
                 receiver_for_self_ty(tcx, receiver_ty, trait_object_ty, method.def_id);
 
             match abi_of_ty(trait_object_receiver) {
-                &Abi::ScalarPair(..) => (),
+                Some(Abi::ScalarPair(..)) => (),
                 abi => {
                     tcx.sess.delay_span_bug(
                         tcx.def_span(method.def_id),
                         &format!(
-                            "receiver when `Self = {}` should have a ScalarPair ABI; \
-                                 found {:?}",
+                            "receiver when `Self = {}` should have a ScalarPair ABI; found {:?}",
                             trait_object_ty, abi
                         ),
                     );