Auto merge of #68174 - JohnTitor:rollup-ix4amrj, r=JohnTitor

Rollup of 8 pull requests

Successful merges:

 - #67313 (Document more use cases of dataflow)
 - #67959 (rustdoc: improve stability mark arrows)
 - #68097 (Specify units for test timeout environment variables)
 - #68135 (restore some rustc_parse visibilities for rustfmt)
 - #68145 (Expose `context::CheckLintNameResult`)
 - #68156 (Fix crate paths in comments)
 - #68157 (Clean up E0186 explanation)
 - #68161 (Fix system call docs for time::Instant)

Failed merges:

r? @ghost

13 files changed, 73 insertions, 19 deletions

diff --git a/src/librustc_error_codes/error_codes/E0186.md b/src/librustc_error_codes/error_codes/E0186.md
index 9135d5c1d5e..7db1e843323 100644
--- a/src/librustc_error_codes/error_codes/E0186.md
+++ b/src/librustc_error_codes/error_codes/E0186.md
@@ -2,7 +2,7 @@ An associated function for a trait was defined to be a method (i.e., to take a
 `self` parameter), but an implementation of the trait declared the same function
 to be static.
 
-Here's an example of this error:
+Erroneous code example:
 
 ```compile_fail,E0186
 trait Foo {
@@ -17,3 +17,19 @@ impl Foo for Bar {
     fn foo() {}
 }
 ```
+
+When a type implements a trait's associated function, it has to use the same
+signature. So in this case, since `Foo::foo` takes `self` as argument and
+does not return anything, its implementation on `Bar` should be the same:
+
+```
+trait Foo {
+    fn foo(&self);
+}
+
+struct Bar;
+
+impl Foo for Bar {
+    fn foo(&self) {} // ok!
+}
+```
diff --git a/src/librustc_feature/lib.rs b/src/librustc_feature/lib.rs
index 71a46427925..01546f78257 100644
--- a/src/librustc_feature/lib.rs
+++ b/src/librustc_feature/lib.rs
@@ -1,7 +1,8 @@
 //! # Feature gates
 //!
 //! This crate declares the set of past and present unstable features in the compiler.
-//! Feature gate checking itself is done in `libsyntax/feature_gate/check.rs` at the moment.
+//! Feature gate checking itself is done in `librustc_ast_passes/feature_gate.rs`
+//! at the moment.
 //!
 //! Features are enabled in programs via the crate-level attributes of
 //! `#![feature(...)]` with a comma-separated list of features.
diff --git a/src/librustc_lint/builtin.rs b/src/librustc_lint/builtin.rs
index 15a8332a284..6aa809a706e 100644
--- a/src/librustc_lint/builtin.rs
+++ b/src/librustc_lint/builtin.rs
@@ -1812,7 +1812,7 @@ declare_lint! {
 }
 
 declare_lint_pass!(
-    /// Check for used feature gates in `INCOMPLETE_FEATURES` in `feature_gate.rs`.
+    /// Check for used feature gates in `INCOMPLETE_FEATURES` in `librustc_feature/active.rs`.
     IncompleteFeatures => [INCOMPLETE_FEATURES]
 );
 
diff --git a/src/librustc_lint/lib.rs b/src/librustc_lint/lib.rs
index 6e3382dee9a..78e9d0f14f2 100644
--- a/src/librustc_lint/lib.rs
+++ b/src/librustc_lint/lib.rs
@@ -76,7 +76,7 @@ use unused::*;
 
 /// Useful for other parts of the compiler / Clippy.
 pub use builtin::SoftLints;
-pub use context::{EarlyContext, LateContext, LintContext, LintStore};
+pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
 pub use early::check_ast_crate;
 pub use late::check_crate;
 pub use passes::{EarlyLintPass, LateLintPass};
diff --git a/src/librustc_mir/dataflow/mod.rs b/src/librustc_mir/dataflow/mod.rs
index 01f6177a93a..e29730f267c 100644
--- a/src/librustc_mir/dataflow/mod.rs
+++ b/src/librustc_mir/dataflow/mod.rs
@@ -668,6 +668,26 @@ pub trait BottomValue {
     const BOTTOM_VALUE: bool;
 
     /// Merges `in_set` into `inout_set`, returning `true` if `inout_set` changed.
+    ///
+    /// It is almost certainly wrong to override this, since it automatically applies
+    /// * `inout_set & in_set` if `BOTTOM_VALUE == true`
+    /// * `inout_set | in_set` if `BOTTOM_VALUE == false`
+    ///
+    /// This means that if a bit is not `BOTTOM_VALUE`, it is propagated into all target blocks.
+    /// For clarity, the above statement again from a different perspective:
+    /// A bit in the block's entry set is `!BOTTOM_VALUE` if *any* predecessor block's bit value is
+    /// `!BOTTOM_VALUE`.
+    ///
+    /// There are situations where you want the opposite behaviour: propagate only if *all*
+    /// predecessor blocks's value is `!BOTTOM_VALUE`.
+    /// E.g. if you want to know whether a bit is *definitely* set at a specific location. This
+    /// means that all code paths leading to the location must have set the bit, instead of any
+    /// code path leading there.
+    ///
+    /// If you want this kind of "definitely set" analysis, you need to
+    /// 1. Invert `BOTTOM_VALUE`
+    /// 2. Reset the `entry_set` in `start_block_effect` to `!BOTTOM_VALUE`
+    /// 3. Override `join` to do the opposite from what it's doing now.
     #[inline]
     fn join<T: Idx>(&self, inout_set: &mut BitSet<T>, in_set: &BitSet<T>) -> bool {
         if Self::BOTTOM_VALUE == false {
@@ -685,7 +705,9 @@ pub trait BottomValue {
 /// for each block individually. The entry set for all other basic blocks is
 /// initialized to `Self::BOTTOM_VALUE`. The dataflow analysis then
 /// iteratively modifies the various entry sets (but leaves the the transfer
-/// function unchanged).
+/// function unchanged). `BottomValue::join` is used to merge the bitsets from
+/// two blocks (e.g. when two blocks' terminator jumps to a single block, that
+/// target block's state is the merged state of both incoming blocks).
 pub trait BitDenotation<'tcx>: BottomValue {
     /// Specifies what index type is used to access the bitvector.
     type Idx: Idx;
diff --git a/src/librustc_parse/parser/mod.rs b/src/librustc_parse/parser/mod.rs
index a1035d320b3..1368230168e 100644
--- a/src/librustc_parse/parser/mod.rs
+++ b/src/librustc_parse/parser/mod.rs
@@ -2,6 +2,7 @@ pub mod attr;
 mod expr;
 mod item;
 mod module;
+pub use module::{ModulePath, ModulePathSuccess};
 mod pat;
 mod path;
 mod ty;
@@ -117,7 +118,8 @@ pub struct Parser<'a> {
     /// Used to determine the path to externally loaded source files.
     pub(super) directory: Directory<'a>,
     /// `true` to parse sub-modules in other files.
-    pub(super) recurse_into_file_modules: bool,
+    // Public for rustfmt usage.
+    pub recurse_into_file_modules: bool,
     /// Name of the root module this parser originated from. If `None`, then the
     /// name is not known. This does not change while the parser is descending
     /// into modules, and sub-parsers have new values for this name.
@@ -126,7 +128,8 @@ pub struct Parser<'a> {
     token_cursor: TokenCursor,
     desugar_doc_comments: bool,
     /// `true` we should configure out of line modules as we parse.
-    cfg_mods: bool,
+    // Public for rustfmt usage.
+    pub cfg_mods: bool,
     /// This field is used to keep track of how many left angle brackets we have seen. This is
     /// required in order to detect extra leading left angle brackets (`<` characters) and error
     /// appropriately.
@@ -483,7 +486,8 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
+    // Public for rustfmt usage.
+    pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
         self.parse_ident_common(true)
     }
 
@@ -540,7 +544,8 @@ impl<'a> Parser<'a> {
 
     /// If the next token is the given keyword, eats it and returns `true`.
     /// Otherwise, returns `false`. An expectation is also added for diagnostics purposes.
-    fn eat_keyword(&mut self, kw: Symbol) -> bool {
+    // Public for rustfmt usage.
+    pub fn eat_keyword(&mut self, kw: Symbol) -> bool {
         if self.check_keyword(kw) {
             self.bump();
             true
diff --git a/src/librustc_parse/parser/module.rs b/src/librustc_parse/parser/module.rs
index 3254ab5b463..6ce94d3c679 100644
--- a/src/librustc_parse/parser/module.rs
+++ b/src/librustc_parse/parser/module.rs
@@ -14,13 +14,15 @@ use syntax::token::{self, TokenKind};
 use std::path::{self, Path, PathBuf};
 
 /// Information about the path to a module.
-pub(super) struct ModulePath {
+// Public for rustfmt usage.
+pub struct ModulePath {
     name: String,
     path_exists: bool,
     pub result: Result<ModulePathSuccess, Error>,
 }
 
-pub(super) struct ModulePathSuccess {
+// Public for rustfmt usage.
+pub struct ModulePathSuccess {
     pub path: PathBuf,
     pub directory_ownership: DirectoryOwnership,
 }
@@ -177,7 +179,8 @@ impl<'a> Parser<'a> {
         }
     }
 
-    pub(super) fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
+    // Public for rustfmt usage.
+    pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
         if let Some(s) = attr::first_attr_value_str_by_name(attrs, sym::path) {
             let s = s.as_str();
 
@@ -194,7 +197,8 @@ impl<'a> Parser<'a> {
     }
 
     /// Returns a path to a module.
-    pub(super) fn default_submod_path(
+    // Public for rustfmt usage.
+    pub fn default_submod_path(
         id: ast::Ident,
         relative: Option<ast::Ident>,
         dir_path: &Path,
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index 62fe23029d9..a91fdb7a10e 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -542,11 +542,11 @@ h4 > code, h3 > code, .invisible > code {
 }
 
 .content .stability::before {
-	content: '˪';
-	font-size: 30px;
+	content: '⬑';
+	font-size: 25px;
 	position: absolute;
-	top: -9px;
-	left: -13px;
+	top: -6px;
+	left: -19px;
 }
 
 .content .impl-items .method, .content .impl-items > .type, .impl-items > .associatedconstant {
diff --git a/src/librustdoc/html/static/themes/dark.css b/src/librustdoc/html/static/themes/dark.css
index f46bd6d6a10..9a0e7bbabcb 100644
--- a/src/librustdoc/html/static/themes/dark.css
+++ b/src/librustdoc/html/static/themes/dark.css
@@ -105,6 +105,8 @@ pre {
 .content .highlighted.primitive { background-color: #00708a; }
 .content .highlighted.keyword { background-color: #884719; }
 
+.content .stability::before { color: #ccc; }
+
 .content span.enum, .content a.enum, .block a.current.enum { color: #82b089; }
 .content span.struct, .content a.struct, .block a.current.struct { color: #2dbfb8; }
 .content span.type, .content a.type, .block a.current.type { color: #ff7f00; }
diff --git a/src/librustdoc/html/static/themes/light.css b/src/librustdoc/html/static/themes/light.css
index ca67b1c1f82..ca8ea1c456a 100644
--- a/src/librustdoc/html/static/themes/light.css
+++ b/src/librustdoc/html/static/themes/light.css
@@ -105,6 +105,8 @@ pre {
 .content .highlighted.primitive { background-color: #9aecff; }
 .content .highlighted.keyword { background-color: #f99650; }
 
+.content .stability::before { color: #ccc; }
+
 .content span.enum, .content a.enum, .block a.current.enum { color: #508157; }
 .content span.struct, .content a.struct, .block a.current.struct { color: #ad448e; }
 .content span.type, .content a.type, .block a.current.type { color: #ba5d00; }
diff --git a/src/libstd/time.rs b/src/libstd/time.rs
index 0dce8f810eb..0b6e728dceb 100644
--- a/src/libstd/time.rs
+++ b/src/libstd/time.rs
@@ -67,7 +67,7 @@ pub use core::time::Duration;
 /// |:---------:|:--------------------------------------------------------------------:|
 /// | Cloud ABI | [clock_time_get (Monotonic Clock)]                                   |
 /// | SGX       | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
-/// | UNIX      | [clock_time_get (Monotonic Clock)]                                   |
+/// | UNIX      | [clock_gettime (Monotonic Clock)]                                    |
 /// | Darwin    | [mach_absolute_time]                                                 |
 /// | VXWorks   | [clock_gettime (Monotonic Clock)]                                    |
 /// | WASI      | [__wasi_clock_time_get (Monotonic Clock)]                            |
diff --git a/src/libtest/cli.rs b/src/libtest/cli.rs
index ea6d632f48a..edff8bea0f3 100644
--- a/src/libtest/cli.rs
+++ b/src/libtest/cli.rs
@@ -125,6 +125,8 @@ fn optgroups() -> getopts::Options {
             `RUST_TEST_TIME_DOCTEST` environment variables.
 
             Expected format of environment variable is `VARIABLE=WARN_TIME,CRITICAL_TIME`.
+            Durations must be specified in milliseconds, e.g. `500,2000` means that the warn time
+            is 0.5 seconds, and the critical time is 2 seconds.
 
             Not available for --format=terse",
             "plain|colored",
diff --git a/src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.rs b/src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.rs
index 0d804f012bc..92c5c202502 100644
--- a/src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.rs
+++ b/src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.rs
@@ -12,7 +12,7 @@
 // the change when it happens.
 //
 // At the time of authoring, the attributes here are listed in the
-// order that they occur in libsyntax/feature_gate.rs.
+// order that they occur in `librustc_feature`.
 //
 // Any builtin attributes that:
 //