Auto merge of #60510 - Centril:rollup-gsndjbp, r=Centril

Rollup of 12 pull requests

Successful merges:

 - #59928 (Make deprecation lint `ambiguous_associated_items` deny-by-default)
 - #60220 (report fatal errors during doctest parsing)
 - #60373 (Tidy: ensure lang features are sorted by since)
 - #60388 (Disallow non-explicit elided lifetimes in async fn)
 - #60393 ( Do not suggest incorrect syntax on pattern type error due to borrow)
 - #60401 (Rename `RUST_LOG` to `RUSTC_LOG`)
 - #60409 (Require a trait in the bounds of existential types)
 - #60455 (Resolve match arm ty when arms diverge)
 - #60457 (Const prop refactoring)
 - #60467 (Avoid repeated interning of static strings.)
 - #60478 (minor compiler doc tweaks)
 - #60501 (Propagate mutability from arguments to local bindings in async fn)

Failed merges:

r? @ghost

Cargo.lock

@@ -3556,6 +3556,7 @@ dependencies = [
 name = "tidy"
 version = "0.1.0"
 dependencies = [
+ "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.82 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.33 (registry+https://github.com/rust-lang/crates.io-index)",

src/bootstrap/native.rs

@@ -436,7 +436,7 @@ fn configure_cmake(builder: &Builder<'_>,
     }
 
     if env::var_os("SCCACHE_ERROR_LOG").is_some() {
-        cfg.env("RUST_LOG", "sccache=warn");
+        cfg.env("RUSTC_LOG", "sccache=warn");
     }
 }
 

src/librustc/error_codes.rs

@@ -362,10 +362,6 @@ struct Foo1 { x: &bool }
               // ^ expected lifetime parameter
 struct Foo2<'a> { x: &'a bool } // correct
 
-impl Foo2 {}
-  // ^^^^ expected lifetime parameter
-impl<'a> Foo2<'a> {} // correct
-
 struct Bar1 { x: Foo2 }
               // ^^^^ expected lifetime parameter
 struct Bar2<'a> { x: Foo2<'a> } // correct
@@ -2208,4 +2204,5 @@ register_diagnostics! {
     E0710, // an unknown tool name found in scoped lint
     E0711, // a feature has been declared with conflicting stability attributes
 //  E0702, // replaced with a generic attribute input check
+    E0726, // non-explicit (not `'_`) elided lifetime in unsupported position
 }

src/librustc/hir/lowering.rs

@@ -2110,15 +2110,49 @@ impl<'a> LoweringContext<'a> {
                         .expect("already checked that type args or bindings exist");
                     (false, first_generic_span.shrink_to_lo(), format!("{}, ", anon_lt_suggestion))
                 };
-                self.sess.buffer_lint_with_diagnostic(
-                    ELIDED_LIFETIMES_IN_PATHS,
-                    CRATE_NODE_ID,
-                    path_span,
-                    "hidden lifetime parameters in types are deprecated",
-                    builtin::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
-                        expected_lifetimes, path_span, incl_angl_brckt, insertion_span, suggestion
-                    )
-                );
+                match self.anonymous_lifetime_mode {
+                    // In create-parameter mode we error here because we don't want to support
+                    // deprecated impl elision in new features like impl elision and `async fn`,
+                    // both of which work using the `CreateParameter` mode:
+                    //
+                    //     impl Foo for std::cell::Ref<u32> // note lack of '_
+                    //     async fn foo(_: std::cell::Ref<u32>) { ... }
+                    AnonymousLifetimeMode::CreateParameter => {
+                        let mut err = struct_span_err!(
+                            self.sess,
+                            path_span,
+                            E0726,
+                            "implicit elided lifetime not allowed here"
+                        );
+                        crate::lint::builtin::add_elided_lifetime_in_path_suggestion(
+                            &self.sess,
+                            &mut err,
+                            expected_lifetimes,
+                            path_span,
+                            incl_angl_brckt,
+                            insertion_span,
+                            suggestion,
+                        );
+                        err.emit();
+                    }
+                    AnonymousLifetimeMode::PassThrough |
+                    AnonymousLifetimeMode::ReportError |
+                    AnonymousLifetimeMode::Replace(_) => {
+                        self.sess.buffer_lint_with_diagnostic(
+                            ELIDED_LIFETIMES_IN_PATHS,
+                            CRATE_NODE_ID,
+                            path_span,
+                            "hidden lifetime parameters in types are deprecated",
+                            builtin::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
+                                expected_lifetimes,
+                                path_span,
+                                incl_angl_brckt,
+                                insertion_span,
+                                suggestion,
+                            )
+                        );
+                    }
+                }
             }
         }
 
@@ -5335,13 +5369,15 @@ impl<'a> LoweringContext<'a> {
 
     fn elided_path_lifetime(&mut self, span: Span) -> hir::Lifetime {
         match self.anonymous_lifetime_mode {
-            // N.B., We intentionally ignore the create-parameter mode here
-            // and instead "pass through" to resolve-lifetimes, which will then
-            // report an error. This is because we don't want to support
-            // impl elision for deprecated forms like
-            //
-            //     impl Foo for std::cell::Ref<u32> // note lack of '_
-            AnonymousLifetimeMode::CreateParameter |
+            AnonymousLifetimeMode::CreateParameter => {
+                // We should have emitted E0726 when processing this path above
+                self.sess.delay_span_bug(
+                    span,
+                    "expected 'implicit elided lifetime not allowed' error",
+                );
+                let id = self.sess.next_node_id();
+                self.new_named_lifetime(id, span, hir::LifetimeName::Error)
+            }
             // This is the normal case.
             AnonymousLifetimeMode::PassThrough => self.new_implicit_lifetime(span),
 

src/librustc/hir/mod.rs

@@ -1927,6 +1927,9 @@ pub enum ArgSource {
 /// Represents the header (not the body) of a function declaration.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
 pub struct FnDecl {
+    /// The types of the function's arguments.
+    ///
+    /// Additional argument data is stored in the function's [body](Body::arguments).
     pub inputs: HirVec<Ty>,
     pub output: FunctionRetTy,
     pub c_variadic: bool,

src/librustc/infer/error_reporting/mod.rs

@@ -644,7 +644,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                         for sp in prior_arms {
                             err.span_label(*sp, format!(
                                 "this is found to be of type `{}`",
-                                last_ty,
+                                self.resolve_type_vars_if_possible(&last_ty),
                             ));
                         }
                     } else if let Some(sp) = prior_arms.last() {

src/librustc/infer/mod.rs

@@ -704,7 +704,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     /// potentially leaving "dangling type variables" behind.
     /// In such cases, an assertion will fail when attempting to
     /// register obligations, within a snapshot. Very useful, much
-    /// better than grovelling through megabytes of `RUST_LOG` output.
+    /// better than grovelling through megabytes of `RUSTC_LOG` output.
     ///
     /// HOWEVER, in some cases the flag is unhelpful. In particular, we
     /// sometimes create a "mini-fulfilment-cx" in which we enroll

src/librustc/lint/builtin.rs

@@ -376,7 +376,7 @@ declare_lint! {
 
 declare_lint! {
     pub AMBIGUOUS_ASSOCIATED_ITEMS,
-    Warn,
+    Deny,
     "ambiguous associated items"
 }
 
@@ -477,6 +477,48 @@ pub enum BuiltinLintDiagnostics {
     RedundantImport(Vec<(Span, bool)>, ast::Ident),
 }
 
+pub(crate) fn add_elided_lifetime_in_path_suggestion(
+    sess: &Session,
+    db: &mut DiagnosticBuilder<'_>,
+    n: usize,
+    path_span: Span,
+    incl_angl_brckt: bool,
+    insertion_span: Span,
+    anon_lts: String,
+) {
+    let (replace_span, suggestion) = if incl_angl_brckt {
+        (insertion_span, anon_lts)
+    } else {
+        // When possible, prefer a suggestion that replaces the whole
+        // `Path<T>` expression with `Path<'_, T>`, rather than inserting `'_, `
+        // at a point (which makes for an ugly/confusing label)
+        if let Ok(snippet) = sess.source_map().span_to_snippet(path_span) {
+            // But our spans can get out of whack due to macros; if the place we think
+            // we want to insert `'_` isn't even within the path expression's span, we
+            // should bail out of making any suggestion rather than panicking on a
+            // subtract-with-overflow or string-slice-out-out-bounds (!)
+            // FIXME: can we do better?
+            if insertion_span.lo().0 < path_span.lo().0 {
+                return;
+            }
+            let insertion_index = (insertion_span.lo().0 - path_span.lo().0) as usize;
+            if insertion_index > snippet.len() {
+                return;
+            }
+            let (before, after) = snippet.split_at(insertion_index);
+            (path_span, format!("{}{}{}", before, anon_lts, after))
+        } else {
+            (insertion_span, anon_lts)
+        }
+    };
+    db.span_suggestion(
+        replace_span,
+        &format!("indicate the anonymous lifetime{}", if n >= 2 { "s" } else { "" }),
+        suggestion,
+        Applicability::MachineApplicable
+    );
+}
+
 impl BuiltinLintDiagnostics {
     pub fn run(self, sess: &Session, db: &mut DiagnosticBuilder<'_>) {
         match self {
@@ -521,36 +563,14 @@ impl BuiltinLintDiagnostics {
             BuiltinLintDiagnostics::ElidedLifetimesInPaths(
                 n, path_span, incl_angl_brckt, insertion_span, anon_lts
             ) => {
-                let (replace_span, suggestion) = if incl_angl_brckt {
-                    (insertion_span, anon_lts)
-                } else {
-                    // When possible, prefer a suggestion that replaces the whole
-                    // `Path<T>` expression with `Path<'_, T>`, rather than inserting `'_, `
-                    // at a point (which makes for an ugly/confusing label)
-                    if let Ok(snippet) = sess.source_map().span_to_snippet(path_span) {
-                        // But our spans can get out of whack due to macros; if the place we think
-                        // we want to insert `'_` isn't even within the path expression's span, we
-                        // should bail out of making any suggestion rather than panicking on a
-                        // subtract-with-overflow or string-slice-out-out-bounds (!)
-                        // FIXME: can we do better?
-                        if insertion_span.lo().0 < path_span.lo().0 {
-                            return;
-                        }
-                        let insertion_index = (insertion_span.lo().0 - path_span.lo().0) as usize;
-                        if insertion_index > snippet.len() {
-                            return;
-                        }
-                        let (before, after) = snippet.split_at(insertion_index);
-                        (path_span, format!("{}{}{}", before, anon_lts, after))
-                    } else {
-                        (insertion_span, anon_lts)
-                    }
-                };
-                db.span_suggestion(
-                    replace_span,
-                    &format!("indicate the anonymous lifetime{}", if n >= 2 { "s" } else { "" }),
-                    suggestion,
-                    Applicability::MachineApplicable
+                add_elided_lifetime_in_path_suggestion(
+                    sess,
+                    db,
+                    n,
+                    path_span,
+                    incl_angl_brckt,
+                    insertion_span,
+                    anon_lts,
                 );
             }
             BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {

src/librustc/lint/context.rs

@@ -757,12 +757,12 @@ impl<'a, 'tcx> LateContext<'a, 'tcx> {
     /// Check if a `DefId`'s path matches the given absolute type path usage.
     ///
     /// # Examples
-    /// ```rust,ignore (no `cx` or `def_id` available)
+    ///
+    /// ```rust,ignore (no context or def id available)
     /// if cx.match_def_path(def_id, &["core", "option", "Option"]) {
     ///     // The given `def_id` is that of an `Option` type
     /// }
     /// ```
-    // Uplifted from rust-lang/rust-clippy
     pub fn match_def_path(&self, def_id: DefId, path: &[&str]) -> bool {
         let names = self.get_def_path(def_id);
 
@@ -772,13 +772,13 @@ impl<'a, 'tcx> LateContext<'a, 'tcx> {
     /// Gets the absolute path of `def_id` as a vector of `&str`.
     ///
     /// # Examples
-    /// ```rust,ignore (no `cx` or `def_id` available)
+    ///
+    /// ```rust,ignore (no context or def id available)
     /// let def_path = cx.get_def_path(def_id);
     /// if let &["core", "option", "Option"] = &def_path[..] {
     ///     // The given `def_id` is that of an `Option` type
     /// }
     /// ```
-    // Uplifted from rust-lang/rust-clippy
     pub fn get_def_path(&self, def_id: DefId) -> Vec<LocalInternedString> {
         pub struct AbsolutePathPrinter<'a, 'tcx> {
             pub tcx: TyCtxt<'a, 'tcx, 'tcx>,

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -784,26 +784,30 @@ pub fn file_metadata(cx: &CodegenCx<'ll, '_>,
            file_name,
            defining_crate);
 
-    let directory = if defining_crate == LOCAL_CRATE {
-        &cx.sess().working_dir.0
+    let file_name = &file_name.to_string();
+    let file_name_symbol = Symbol::intern(file_name);
+    if defining_crate == LOCAL_CRATE {
+        let directory = &cx.sess().working_dir.0.to_string_lossy();
+        file_metadata_raw(cx, file_name, Some(file_name_symbol),
+                          directory, Some(Symbol::intern(directory)))
     } else {
         // If the path comes from an upstream crate we assume it has been made
         // independent of the compiler's working directory one way or another.
-        Path::new("")
-    };
-
-    file_metadata_raw(cx, &file_name.to_string(), &directory.to_string_lossy())
+        file_metadata_raw(cx, file_name, Some(file_name_symbol), "", None)
+    }
 }
 
 pub fn unknown_file_metadata(cx: &CodegenCx<'ll, '_>) -> &'ll DIFile {
-    file_metadata_raw(cx, "<unknown>", "")
+    file_metadata_raw(cx, "<unknown>", None, "", None)
 }
 
 fn file_metadata_raw(cx: &CodegenCx<'ll, '_>,
                      file_name: &str,
-                     directory: &str)
+                     file_name_symbol: Option<Symbol>,
+                     directory: &str,
+                     directory_symbol: Option<Symbol>)
                      -> &'ll DIFile {
-    let key = (Symbol::intern(file_name), Symbol::intern(directory));
+    let key = (file_name_symbol, directory_symbol);
 
     if let Some(file_metadata) = debug_context(cx).created_files.borrow().get(&key) {
         return *file_metadata;

src/librustc_codegen_llvm/debuginfo/mod.rs

@@ -63,7 +63,7 @@ pub struct CrateDebugContext<'a, 'tcx> {
     llcontext: &'a llvm::Context,
     llmod: &'a llvm::Module,
     builder: &'a mut DIBuilder<'a>,
-    created_files: RefCell<FxHashMap<(Symbol, Symbol), &'a DIFile>>,
+    created_files: RefCell<FxHashMap<(Option<Symbol>, Option<Symbol>), &'a DIFile>>,
     created_enum_disr_types: RefCell<FxHashMap<(DefId, layout::Primitive), &'a DIType>>,
 
     type_map: RefCell<TypeMap<'a, 'tcx>>,

src/librustc_driver/lib.rs

@@ -1163,7 +1163,7 @@ pub fn report_ices_to_stderr_if_any<F: FnOnce() -> R, R>(f: F) -> Result<R, Erro
 /// This allows tools to enable rust logging without having to magically match rustc's
 /// log crate version
 pub fn init_rustc_env_logger() {
-    env_logger::init();
+    env_logger::init_from_env("RUSTC_LOG");
 }
 
 pub fn main() {