Auto merge of #67903 - Dylan-DPC:rollup-k9djyrf, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - #67818 (rustdoc: Avoid panic when parsing codeblocks for playground links)
 - #67845 (Also remove const-hack for abs)
 - #67879 (Remove negative number check from float sqrt)
 - #67881 (Add backticks to various diagnostics)
 - #67882 (remove bespoke flock bindings)

Failed merges:

r? @ghost

70 files changed, 228 insertions, 299 deletions

diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 605ab98219f..b6b4a46e0b8 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -2001,6 +2001,9 @@ $EndFeature, "
             #[inline]
             #[rustc_inherit_overflow_checks]
             pub const fn abs(self) -> Self {
+                // Note that the #[inline] above means that the overflow
+                // semantics of the subtraction depend on the crate we're being
+                // inlined into.
                 if self.is_negative() {
                     -self
                 } else {
diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index e2b70abe6f0..69c5ea56ad6 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -661,7 +661,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             },
             ObligationCauseCode::IfExpression(box IfExpressionCause { then, outer, semicolon }) => {
                 err.span_label(then, "expected because of this");
-                outer.map(|sp| err.span_label(sp, "if and else have incompatible types"));
+                outer.map(|sp| err.span_label(sp, "`if` and `else` have incompatible types"));
                 if let Some(sp) = semicolon {
                     err.span_suggestion_short(
                         sp,
@@ -1883,13 +1883,13 @@ impl<'tcx> ObligationCause<'tcx> {
                     hir::MatchSource::TryDesugar => {
                         "try expression alternatives have incompatible types"
                     }
-                    _ => "match arms have incompatible types",
+                    _ => "`match` arms have incompatible types",
                 })
             }
-            IfExpression { .. } => Error0308("if and else have incompatible types"),
-            IfExpressionWithNoElse => Error0317("if may be missing an else clause"),
-            MainFunctionType => Error0580("main function has wrong type"),
-            StartFunctionType => Error0308("start function has wrong type"),
+            IfExpression { .. } => Error0308("`if` and `else` have incompatible types"),
+            IfExpressionWithNoElse => Error0317("`if` may be missing an `else` clause"),
+            MainFunctionType => Error0580("`main` function has wrong type"),
+            StartFunctionType => Error0308("`#[start]` function has wrong type"),
             IntrinsicType => Error0308("intrinsic has wrong type"),
             MethodReceiver => Error0308("mismatched `self` parameter type"),
 
@@ -1917,12 +1917,12 @@ impl<'tcx> ObligationCause<'tcx> {
             ExprAssignable => "expression is assignable",
             MatchExpressionArm(box MatchExpressionArmCause { source, .. }) => match source {
                 hir::MatchSource::IfLetDesugar { .. } => "`if let` arms have compatible types",
-                _ => "match arms have compatible types",
+                _ => "`match` arms have compatible types",
             },
-            IfExpression { .. } => "if and else have incompatible types",
-            IfExpressionWithNoElse => "if missing an else returns ()",
+            IfExpression { .. } => "`if` and `else` have incompatible types",
+            IfExpressionWithNoElse => "`if` missing an `else` returns `()`",
             MainFunctionType => "`main` function has the correct type",
-            StartFunctionType => "`start` function has the correct type",
+            StartFunctionType => "`#[start]` function has the correct type",
             IntrinsicType => "intrinsic has the correct type",
             MethodReceiver => "method receiver has the correct type",
             _ => "types are compatible",
diff --git a/src/librustc_data_structures/flock.rs b/src/librustc_data_structures/flock.rs
index 01f25a054f0..e3282c5d276 100644
--- a/src/librustc_data_structures/flock.rs
+++ b/src/librustc_data_structures/flock.rs
@@ -13,96 +13,9 @@ use std::path::Path;
 cfg_if! {
     if #[cfg(unix)] {
         use std::ffi::{CString, OsStr};
+        use std::mem;
         use std::os::unix::prelude::*;
 
-        #[cfg(any(target_os = "linux", target_os = "android"))]
-        mod os {
-            #[repr(C)]
-            pub struct flock {
-                pub l_type: libc::c_short,
-                pub l_whence: libc::c_short,
-                pub l_start: libc::off_t,
-                pub l_len: libc::off_t,
-                pub l_pid: libc::pid_t,
-
-                // not actually here, but brings in line with freebsd
-                pub l_sysid: libc::c_int,
-            }
-        }
-
-        #[cfg(target_os = "freebsd")]
-        mod os {
-            #[repr(C)]
-            pub struct flock {
-                pub l_start: libc::off_t,
-                pub l_len: libc::off_t,
-                pub l_pid: libc::pid_t,
-                pub l_type: libc::c_short,
-                pub l_whence: libc::c_short,
-                pub l_sysid: libc::c_int,
-            }
-        }
-
-        #[cfg(any(target_os = "dragonfly",
-                  target_os = "netbsd",
-                  target_os = "openbsd"))]
-        mod os {
-            #[repr(C)]
-            pub struct flock {
-                pub l_start: libc::off_t,
-                pub l_len: libc::off_t,
-                pub l_pid: libc::pid_t,
-                pub l_type: libc::c_short,
-                pub l_whence: libc::c_short,
-
-                // not actually here, but brings in line with freebsd
-                pub l_sysid: libc::c_int,
-            }
-        }
-
-        #[cfg(target_os = "haiku")]
-        mod os {
-            #[repr(C)]
-            pub struct flock {
-                pub l_type: libc::c_short,
-                pub l_whence: libc::c_short,
-                pub l_start: libc::off_t,
-                pub l_len: libc::off_t,
-                pub l_pid: libc::pid_t,
-
-                // not actually here, but brings in line with freebsd
-                pub l_sysid: libc::c_int,
-            }
-        }
-
-        #[cfg(any(target_os = "macos", target_os = "ios"))]
-        mod os {
-            #[repr(C)]
-            pub struct flock {
-                pub l_start: libc::off_t,
-                pub l_len: libc::off_t,
-                pub l_pid: libc::pid_t,
-                pub l_type: libc::c_short,
-                pub l_whence: libc::c_short,
-
-                // not actually here, but brings in line with freebsd
-                pub l_sysid: libc::c_int,
-            }
-        }
-
-        #[cfg(target_os = "solaris")]
-        mod os {
-            #[repr(C)]
-            pub struct flock {
-                pub l_type: libc::c_short,
-                pub l_whence: libc::c_short,
-                pub l_start: libc::off_t,
-                pub l_len: libc::off_t,
-                pub l_sysid: libc::c_int,
-                pub l_pid: libc::pid_t,
-            }
-        }
-
         #[derive(Debug)]
         pub struct Lock {
             fd: libc::c_int,
@@ -132,19 +45,17 @@ cfg_if! {
                 }
 
                 let lock_type = if exclusive {
-                    libc::F_WRLCK as libc::c_short
+                    libc::F_WRLCK
                 } else {
-                    libc::F_RDLCK as libc::c_short
+                    libc::F_RDLCK
                 };
 
-                let flock = os::flock {
-                    l_start: 0,
-                    l_len: 0,
-                    l_pid: 0,
-                    l_whence: libc::SEEK_SET as libc::c_short,
-                    l_type: lock_type,
-                    l_sysid: 0,
-                };
+                let mut flock: libc::flock = unsafe { mem::zeroed() };
+                flock.l_type = lock_type as libc::c_short;
+                flock.l_whence = libc::SEEK_SET as libc::c_short;
+                flock.l_start = 0;
+                flock.l_len = 0;
+
                 let cmd = if wait { libc::F_SETLKW } else { libc::F_SETLK };
                 let ret = unsafe {
                     libc::fcntl(fd, cmd, &flock)
@@ -161,14 +72,12 @@ cfg_if! {
 
         impl Drop for Lock {
             fn drop(&mut self) {
-                let flock = os::flock {
-                    l_start: 0,
-                    l_len: 0,
-                    l_pid: 0,
-                    l_whence: libc::SEEK_SET as libc::c_short,
-                    l_type: libc::F_UNLCK as libc::c_short,
-                    l_sysid: 0,
-                };
+                let mut flock: libc::flock = unsafe { mem::zeroed() };
+                flock.l_type = libc::F_UNLCK as libc::c_short;
+                flock.l_whence = libc::SEEK_SET as libc::c_short;
+                flock.l_start = 0;
+                flock.l_len = 0;
+
                 unsafe {
                     libc::fcntl(self.fd, libc::F_SETLK, &flock);
                     libc::close(self.fd);
diff --git a/src/librustc_passes/entry.rs b/src/librustc_passes/entry.rs
index 3a7d1780d47..910d7523599 100644
--- a/src/librustc_passes/entry.rs
+++ b/src/librustc_passes/entry.rs
@@ -134,7 +134,7 @@ fn find_item(item: &Item<'_>, ctxt: &mut EntryContext<'_, '_>, at_root: bool) {
                 ctxt.start_fn = Some((item.hir_id, item.span));
             } else {
                 struct_span_err!(ctxt.session, item.span, E0138, "multiple `start` functions")
-                    .span_label(ctxt.start_fn.unwrap().1, "previous `start` function here")
+                    .span_label(ctxt.start_fn.unwrap().1, "previous `#[start]` function here")
                     .span_label(item.span, "multiple `start` functions")
                     .emit();
             }
diff --git a/src/librustc_target/spec/wasm32_base.rs b/src/librustc_target/spec/wasm32_base.rs
index 77f5ff09244..47e80e8db19 100644
--- a/src/librustc_target/spec/wasm32_base.rs
+++ b/src/librustc_target/spec/wasm32_base.rs
@@ -81,7 +81,7 @@ pub fn options() -> TargetOptions {
         dynamic_linking: true,
         only_cdylib: true,
 
-        // This means we'll just embed a `start` function in the wasm module
+        // This means we'll just embed a `#[start]` function in the wasm module
         executables: true,
 
         // relatively self-explanatory!
diff --git a/src/librustc_typeck/check/_match.rs b/src/librustc_typeck/check/_match.rs
index 4c0ef45cae5..1f0bc6a8e13 100644
--- a/src/librustc_typeck/check/_match.rs
+++ b/src/librustc_typeck/check/_match.rs
@@ -298,7 +298,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // LL ||         10u32
             //    ||         ^^^^^ expected `i32`, found `u32`
             // LL ||     };
-            //    ||_____- if and else have incompatible types
+            //    ||_____- `if` and `else` have incompatible types
             // ```
             Some(span)
         } else {
@@ -340,7 +340,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // by not pointing at the entire expression:
                 // ```
                 // 2 |       let x = if true {
-                //   |               ------- if and else have incompatible types
+                //   |               ------- `if` and `else` have incompatible types
                 // 3 |           3
                 //   |           - expected because of this
                 // 4 |       } else {
diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
index d7285b9d0bb..db66b7530b2 100644
--- a/src/librustdoc/test.rs
+++ b/src/librustdoc/test.rs
@@ -202,17 +202,7 @@ fn run_test(
     opts: &TestOptions,
     edition: Edition,
 ) -> Result<(), TestFailure> {
-    let (test, line_offset) = match panic::catch_unwind(|| {
-        make_test(test, Some(cratename), as_test_harness, opts, edition)
-    }) {
-        Ok((test, line_offset)) => (test, line_offset),
-        Err(cause) if cause.is::<errors::FatalErrorMarker>() => {
-            // If the parser used by `make_test` panicked due to a fatal error, pass the test code
-            // through unchanged. The error will be reported during compilation.
-            (test.to_owned(), 0)
-        }
-        Err(cause) => panic::resume_unwind(cause),
-    };
+    let (test, line_offset) = make_test(test, Some(cratename), as_test_harness, opts, edition);
 
     // FIXME(#44940): if doctests ever support path remapping, then this filename
     // needs to be the result of `SourceMap::span_to_unmapped_path`.
@@ -362,11 +352,6 @@ fn run_test(
 
 /// Transforms a test into code that can be compiled into a Rust binary, and returns the number of
 /// lines before the test code begins.
-///
-/// # Panics
-///
-/// This function uses the compiler's parser internally. The parser will panic if it encounters a
-/// fatal error while parsing the test.
 pub fn make_test(
     s: &str,
     cratename: Option<&str>,
@@ -401,83 +386,94 @@ pub fn make_test(
 
     // Uses libsyntax to parse the doctest and find if there's a main fn and the extern
     // crate already is included.
-    let (already_has_main, already_has_extern_crate, found_macro) = with_globals(edition, || {
-        use errors::emitter::EmitterWriter;
-        use errors::Handler;
-        use rustc_parse::maybe_new_parser_from_source_str;
-        use rustc_span::source_map::FilePathMapping;
-        use syntax::sess::ParseSess;
-
-        let filename = FileName::anon_source_code(s);
-        let source = crates + &everything_else;
-
-        // Any errors in parsing should also appear when the doctest is compiled for real, so just
-        // send all the errors that libsyntax emits directly into a `Sink` instead of stderr.
-        let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let emitter = EmitterWriter::new(box io::sink(), None, false, false, false, None, false);
-        // FIXME(misdreavus): pass `-Z treat-err-as-bug` to the doctest parser
-        let handler = Handler::with_emitter(false, None, box emitter);
-        let sess = ParseSess::with_span_handler(handler, cm);
-
-        let mut found_main = false;
-        let mut found_extern_crate = cratename.is_none();
-        let mut found_macro = false;
-
-        let mut parser = match maybe_new_parser_from_source_str(&sess, filename, source) {
-            Ok(p) => p,
-            Err(errs) => {
-                for mut err in errs {
-                    err.cancel();
+    let result = rustc_driver::catch_fatal_errors(|| {
+        with_globals(edition, || {
+            use errors::emitter::EmitterWriter;
+            use errors::Handler;
+            use rustc_parse::maybe_new_parser_from_source_str;
+            use rustc_span::source_map::FilePathMapping;
+            use syntax::sess::ParseSess;
+
+            let filename = FileName::anon_source_code(s);
+            let source = crates + &everything_else;
+
+            // Any errors in parsing should also appear when the doctest is compiled for real, so just
+            // send all the errors that libsyntax emits directly into a `Sink` instead of stderr.
+            let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
+            let emitter =
+                EmitterWriter::new(box io::sink(), None, false, false, false, None, false);
+            // FIXME(misdreavus): pass `-Z treat-err-as-bug` to the doctest parser
+            let handler = Handler::with_emitter(false, None, box emitter);
+            let sess = ParseSess::with_span_handler(handler, cm);
+
+            let mut found_main = false;
+            let mut found_extern_crate = cratename.is_none();
+            let mut found_macro = false;
+
+            let mut parser = match maybe_new_parser_from_source_str(&sess, filename, source) {
+                Ok(p) => p,
+                Err(errs) => {
+                    for mut err in errs {
+                        err.cancel();
+                    }
+
+                    return (found_main, found_extern_crate, found_macro);
                 }
+            };
+
+            loop {
+                match parser.parse_item() {
+                    Ok(Some(item)) => {
+                        if !found_main {
+                            if let ast::ItemKind::Fn(..) = item.kind {
+                                if item.ident.name == sym::main {
+                                    found_main = true;
+                                }
+                            }
+                        }
 
-                return (found_main, found_extern_crate, found_macro);
-            }
-        };
+                        if !found_extern_crate {
+                            if let ast::ItemKind::ExternCrate(original) = item.kind {
+                                // This code will never be reached if `cratename` is none because
+                                // `found_extern_crate` is initialized to `true` if it is none.
+                                let cratename = cratename.unwrap();
 
-        loop {
-            match parser.parse_item() {
-                Ok(Some(item)) => {
-                    if !found_main {
-                        if let ast::ItemKind::Fn(..) = item.kind {
-                            if item.ident.name == sym::main {
-                                found_main = true;
+                                match original {
+                                    Some(name) => found_extern_crate = name.as_str() == cratename,
+                                    None => found_extern_crate = item.ident.as_str() == cratename,
+                                }
                             }
                         }
-                    }
-
-                    if !found_extern_crate {
-                        if let ast::ItemKind::ExternCrate(original) = item.kind {
-                            // This code will never be reached if `cratename` is none because
-                            // `found_extern_crate` is initialized to `true` if it is none.
-                            let cratename = cratename.unwrap();
 
-                            match original {
-                                Some(name) => found_extern_crate = name.as_str() == cratename,
-                                None => found_extern_crate = item.ident.as_str() == cratename,
+                        if !found_macro {
+                            if let ast::ItemKind::Mac(..) = item.kind {
+                                found_macro = true;
                             }
                         }
-                    }
 
-                    if !found_macro {
-                        if let ast::ItemKind::Mac(..) = item.kind {
-                            found_macro = true;
+                        if found_main && found_extern_crate {
+                            break;
                         }
                     }
-
-                    if found_main && found_extern_crate {
+                    Ok(None) => break,
+                    Err(mut e) => {
+                        e.cancel();
                         break;
                     }
                 }
-                Ok(None) => break,
-                Err(mut e) => {
-                    e.cancel();
-                    break;
-                }
             }
-        }
 
-        (found_main, found_extern_crate, found_macro)
+            (found_main, found_extern_crate, found_macro)
+        })
     });
+    let (already_has_main, already_has_extern_crate, found_macro) = match result {
+        Ok(result) => result,
+        Err(ErrorReported) => {
+            // If the parser panicked due to a fatal error, pass the test code through unchanged.
+            // The error will be reported during compilation.
+            return (s.to_owned(), 0);
+        }
+    };
 
     // If a doctest's `fn main` is being masked by a wrapper macro, the parsing loop above won't
     // see it. In that case, run the old text-based scan to see if they at least have a main
diff --git a/src/libstd/f32.rs b/src/libstd/f32.rs
index 54e0caeddaa..267d7013b1e 100644
--- a/src/libstd/f32.rs
+++ b/src/libstd/f32.rs
@@ -376,7 +376,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn sqrt(self) -> f32 {
-        if self < 0.0 { NAN } else { unsafe { intrinsics::sqrtf32(self) } }
+        unsafe { intrinsics::sqrtf32(self) }
     }
 
     /// Returns `e^(self)`, (the exponential function).
diff --git a/src/libstd/f64.rs b/src/libstd/f64.rs
index aa32e5fb998..61ce7b29e26 100644
--- a/src/libstd/f64.rs
+++ b/src/libstd/f64.rs
@@ -342,7 +342,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn sqrt(self) -> f64 {
-        if self < 0.0 { NAN } else { unsafe { intrinsics::sqrtf64(self) } }
+        unsafe { intrinsics::sqrtf64(self) }
     }
 
     /// Returns `e^(self)`, (the exponential function).
diff --git a/src/libsyntax/feature_gate/check.rs b/src/libsyntax/feature_gate/check.rs
index 50712058874..0e94a722777 100644
--- a/src/libsyntax/feature_gate/check.rs
+++ b/src/libsyntax/feature_gate/check.rs
@@ -387,8 +387,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                         &self,
                         start,
                         i.span,
-                        "a `#[start]` function is an experimental \
-                                       feature whose signature may change \
+                        "`#[start]` functions are experimental \
+                                       and their signature may change \
                                        over time"
                     );
                 }
diff --git a/src/test/rustdoc/playground-syntax-error.rs b/src/test/rustdoc/playground-syntax-error.rs
new file mode 100644
index 00000000000..8918ae874f8
--- /dev/null
+++ b/src/test/rustdoc/playground-syntax-error.rs
@@ -0,0 +1,21 @@
+#![crate_name = "foo"]
+#![doc(html_playground_url = "https://play.rust-lang.org/")]
+
+/// bar docs
+///
+/// ```edition2015
+/// use std::future::Future;
+/// use std::pin::Pin;
+/// fn foo_recursive(n: usize) -> Pin<Box<dyn Future<Output = ()>>> {
+///     Box::pin(async move {
+///         if n > 0 {
+///             foo_recursive(n - 1).await;
+///         }
+///     })
+/// }
+/// ```
+pub fn bar() {}
+
+// @has foo/fn.bar.html
+// @has - '//a[@class="test-arrow"]' "Run"
+// @has - '//*[@class="docblock"]' 'foo_recursive'
diff --git a/src/test/ui/async-await/issue-66387-if-without-else.rs b/src/test/ui/async-await/issue-66387-if-without-else.rs
index aa5a8db6121..3ab8220b4af 100644
--- a/src/test/ui/async-await/issue-66387-if-without-else.rs
+++ b/src/test/ui/async-await/issue-66387-if-without-else.rs
@@ -1,6 +1,6 @@
 // edition:2018
 async fn f() -> i32 {
-    if true { //~ ERROR if may be missing an else clause
+    if true { //~ ERROR `if` may be missing an `else` clause
         return 0;
     }
     // An `if` block without `else` causes the type table not to have a type for this expr.
diff --git a/src/test/ui/async-await/issue-66387-if-without-else.stderr b/src/test/ui/async-await/issue-66387-if-without-else.stderr
index 42e44472aca..e8e2a48983c 100644
--- a/src/test/ui/async-await/issue-66387-if-without-else.stderr
+++ b/src/test/ui/async-await/issue-66387-if-without-else.stderr
@@ -1,4 +1,4 @@
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/issue-66387-if-without-else.rs:3:5
    |
 LL | /     if true {
diff --git a/src/test/ui/bad/bad-expr-path.rs b/src/test/ui/bad/bad-expr-path.rs
index 99ba93253d1..31fc9cf2cb5 100644
--- a/src/test/ui/bad/bad-expr-path.rs
+++ b/src/test/ui/bad/bad-expr-path.rs
@@ -1,6 +1,6 @@
 mod m1 {}
 
-fn main(arguments: Vec<String>) { //~ ERROR main function has wrong type
+fn main(arguments: Vec<String>) { //~ ERROR `main` function has wrong type
     log(debug, m1::arguments);
     //~^ ERROR cannot find function `log` in this scope
     //~| ERROR cannot find value `debug` in this scope
diff --git a/src/test/ui/bad/bad-expr-path.stderr b/src/test/ui/bad/bad-expr-path.stderr
index faba9911f86..56bb6e2be88 100644
--- a/src/test/ui/bad/bad-expr-path.stderr
+++ b/src/test/ui/bad/bad-expr-path.stderr
@@ -16,7 +16,7 @@ error[E0425]: cannot find value `arguments` in module `m1`
 LL |     log(debug, m1::arguments);
    |                    ^^^^^^^^^ not found in `m1`
 
-error[E0580]: main function has wrong type
+error[E0580]: `main` function has wrong type
   --> $DIR/bad-expr-path.rs:3:1
    |
 LL | fn main(arguments: Vec<String>) {
diff --git a/src/test/ui/bad/bad-expr-path2.rs b/src/test/ui/bad/bad-expr-path2.rs
index 43bd2908042..eb88edb9071 100644
--- a/src/test/ui/bad/bad-expr-path2.rs
+++ b/src/test/ui/bad/bad-expr-path2.rs
@@ -2,7 +2,7 @@ mod m1 {
     pub mod arguments {}
 }
 
-fn main(arguments: Vec<String>) { //~ ERROR main function has wrong type
+fn main(arguments: Vec<String>) { //~ ERROR `main` function has wrong type
     log(debug, m1::arguments);
     //~^ ERROR cannot find function `log` in this scope
     //~| ERROR cannot find value `debug` in this scope
diff --git a/src/test/ui/bad/bad-expr-path2.stderr b/src/test/ui/bad/bad-expr-path2.stderr
index 53b6d35e8f3..e217c45b267 100644
--- a/src/test/ui/bad/bad-expr-path2.stderr
+++ b/src/test/ui/bad/bad-expr-path2.stderr
@@ -16,7 +16,7 @@ error[E0423]: expected value, found module `m1::arguments`
 LL |     log(debug, m1::arguments);
    |                ^^^^^^^^^^^^^ not a value
 
-error[E0580]: main function has wrong type
+error[E0580]: `main` function has wrong type
   --> $DIR/bad-expr-path2.rs:5:1
    |
 LL | fn main(arguments: Vec<String>) {
diff --git a/src/test/ui/bad/bad-main.rs b/src/test/ui/bad/bad-main.rs
index c9e2f02f071..75115996142 100644
--- a/src/test/ui/bad/bad-main.rs
+++ b/src/test/ui/bad/bad-main.rs
@@ -1 +1 @@
-fn main(x: isize) { } //~ ERROR: main function has wrong type [E0580]
+fn main(x: isize) { } //~ ERROR: `main` function has wrong type [E0580]
diff --git a/src/test/ui/bad/bad-main.stderr b/src/test/ui/bad/bad-main.stderr
index 1e57c2488e9..675b66d0578 100644
--- a/src/test/ui/bad/bad-main.stderr
+++ b/src/test/ui/bad/bad-main.stderr
@@ -1,4 +1,4 @@
-error[E0580]: main function has wrong type
+error[E0580]: `main` function has wrong type
   --> $DIR/bad-main.rs:1:1
    |
 LL | fn main(x: isize) { }
diff --git a/src/test/ui/consts/control-flow/issue-50577.if_match.stderr b/src/test/ui/consts/control-flow/issue-50577.if_match.stderr
index 79572c41702..6771224e6cf 100644
--- a/src/test/ui/consts/control-flow/issue-50577.if_match.stderr
+++ b/src/test/ui/consts/control-flow/issue-50577.if_match.stderr
@@ -1,4 +1,4 @@
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/issue-50577.rs:7:16
    |
 LL |         Drop = assert_eq!(1, 1)
diff --git a/src/test/ui/consts/control-flow/issue-50577.rs b/src/test/ui/consts/control-flow/issue-50577.rs
index 7906ec4dc68..9600f8b6aee 100644
--- a/src/test/ui/consts/control-flow/issue-50577.rs
+++ b/src/test/ui/consts/control-flow/issue-50577.rs
@@ -5,7 +5,7 @@
 fn main() {
     enum Foo {
         Drop = assert_eq!(1, 1)
-        //[stock,if_match]~^ ERROR if may be missing an else clause
+        //[stock,if_match]~^ ERROR `if` may be missing an `else` clause
         //[stock]~^^ ERROR `match` is not allowed in a `const`
         //[stock]~| ERROR `match` is not allowed in a `const`
         //[stock]~| ERROR `if` is not allowed in a `const`
diff --git a/src/test/ui/consts/control-flow/issue-50577.stock.stderr b/src/test/ui/consts/control-flow/issue-50577.stock.stderr
index 13b50954292..7d637f5aa96 100644
--- a/src/test/ui/consts/control-flow/issue-50577.stock.stderr
+++ b/src/test/ui/consts/control-flow/issue-50577.stock.stderr
@@ -28,7 +28,7 @@ LL |         Drop = assert_eq!(1, 1)
    = help: add `#![feature(const_if_match)]` to the crate attributes to enable
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/issue-50577.rs:7:16
    |
 LL |         Drop = assert_eq!(1, 1)
diff --git a/src/test/ui/error-codes/E0138.stderr b/src/test/ui/error-codes/E0138.stderr
index 445053a4a89..2dc6976fe0e 100644
--- a/src/test/ui/error-codes/E0138.stderr
+++ b/src/test/ui/error-codes/E0138.stderr
@@ -2,7 +2,7 @@ error[E0138]: multiple `start` functions
   --> $DIR/E0138.rs:7:1
    |
 LL | fn foo(argc: isize, argv: *const *const u8) -> isize { 0 }
-   | ---------------------------------------------------------- previous `start` function here
+   | ---------------------------------------------------------- previous `#[start]` function here
 ...
 LL | fn f(argc: isize, argv: *const *const u8) -> isize { 0 }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ multiple `start` functions
diff --git a/src/test/ui/extern/extern-main-fn.rs b/src/test/ui/extern/extern-main-fn.rs
index dacebfbecf5..ddf2e136f03 100644
--- a/src/test/ui/extern/extern-main-fn.rs
+++ b/src/test/ui/extern/extern-main-fn.rs
@@ -1 +1 @@
-extern fn main() {} //~ ERROR: main function has wrong type [E0580]
+extern fn main() {} //~ ERROR: `main` function has wrong type [E0580]
diff --git a/src/test/ui/extern/extern-main-fn.stderr b/src/test/ui/extern/extern-main-fn.stderr
index 6f6983d4283..9c994985a3e 100644
--- a/src/test/ui/extern/extern-main-fn.stderr
+++ b/src/test/ui/extern/extern-main-fn.stderr
@@ -1,4 +1,4 @@
-error[E0580]: main function has wrong type
+error[E0580]: `main` function has wrong type
   --> $DIR/extern-main-fn.rs:1:1
    |
 LL | extern fn main() {}
diff --git a/src/test/ui/feature-gates/feature-gate-start.rs b/src/test/ui/feature-gates/feature-gate-start.rs
index 0bd4c7c85b7..e617f1c4759 100644
--- a/src/test/ui/feature-gates/feature-gate-start.rs
+++ b/src/test/ui/feature-gates/feature-gate-start.rs
@@ -1,3 +1,3 @@
 #[start]
 fn foo(_: isize, _: *const *const u8) -> isize { 0 }
-//~^ ERROR a `#[start]` function is an experimental feature
+//~^ ERROR `#[start]` functions are experimental
diff --git a/src/test/ui/feature-gates/feature-gate-start.stderr b/src/test/ui/feature-gates/feature-gate-start.stderr
index c769ef8ee92..f42e42ea039 100644
--- a/src/test/ui/feature-gates/feature-gate-start.stderr
+++ b/src/test/ui/feature-gates/feature-gate-start.stderr
@@ -1,4 +1,4 @@
-error[E0658]: a `#[start]` function is an experimental feature whose signature may change over time
+error[E0658]: `#[start]` functions are experimental and their signature may change over time
   --> $DIR/feature-gate-start.rs:2:1
    |
 LL | fn foo(_: isize, _: *const *const u8) -> isize { 0 }
diff --git a/src/test/ui/if-else-type-mismatch.rs b/src/test/ui/if-else-type-mismatch.rs
index 583c3d0b765..1a0a36df2ad 100644
--- a/src/test/ui/if-else-type-mismatch.rs
+++ b/src/test/ui/if-else-type-mismatch.rs
@@ -4,43 +4,43 @@ fn main() {
     } else {
         2u32
     };
-    //~^^ ERROR if and else have incompatible types
+    //~^^ ERROR `if` and `else` have incompatible types
     let _ = if true { 42i32 } else { 42u32 };
-    //~^ ERROR if and else have incompatible types
+    //~^ ERROR `if` and `else` have incompatible types
     let _ = if true {
         3u32;
     } else {
         4u32
     };
-    //~^^ ERROR if and else have incompatible types
+    //~^^ ERROR `if` and `else` have incompatible types
     let _ = if true {
         5u32
     } else {
         6u32;
     };
-    //~^^ ERROR if and else have incompatible types
+    //~^^ ERROR `if` and `else` have incompatible types
     let _ = if true {
         7i32;
     } else {
         8u32
     };
-    //~^^ ERROR if and else have incompatible types
+    //~^^ ERROR `if` and `else` have incompatible types
     let _ = if true {
         9i32
     } else {
         10u32;
     };
-    //~^^ ERROR if and else have incompatible types
+    //~^^ ERROR `if` and `else` have incompatible types
     let _ = if true {
 
     } else {
         11u32
     };
-    //~^^ ERROR if and else have incompatible types
+    //~^^ ERROR `if` and `else` have incompatible types
     let _ = if true {
         12i32
     } else {
 
     };
-    //~^^^ ERROR if and else have incompatible types
+    //~^^^ ERROR `if` and `else` have incompatible types
 }
diff --git a/src/test/ui/if-else-type-mismatch.stderr b/src/test/ui/if-else-type-mismatch.stderr
index 14e8f87393b..9fa190d6c9d 100644
--- a/src/test/ui/if-else-type-mismatch.stderr
+++ b/src/test/ui/if-else-type-mismatch.stderr
@@ -1,4 +1,4 @@
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:5:9
    |
 LL |       let _ = if true {
@@ -9,9 +9,9 @@ LL | |     } else {
 LL | |         2u32
    | |         ^^^^ expected `i32`, found `u32`
 LL | |     };
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:8:38
    |
 LL |     let _ = if true { 42i32 } else { 42u32 };
@@ -19,7 +19,7 @@ LL |     let _ = if true { 42i32 } else { 42u32 };
    |                       |
    |                       expected because of this
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:13:9
    |
 LL |       let _ = if true {
@@ -33,9 +33,9 @@ LL | |     } else {
 LL | |         4u32
    | |         ^^^^ expected `()`, found `u32`
 LL | |     };
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:19:9
    |
 LL |       let _ = if true {
@@ -49,9 +49,9 @@ LL | |         6u32;
    | |         |   help: consider removing this semicolon
    | |         expected `u32`, found `()`
 LL | |     };
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:25:9
    |
 LL |       let _ = if true {
@@ -62,9 +62,9 @@ LL | |     } else {
 LL | |         8u32
    | |         ^^^^ expected `()`, found `u32`
 LL | |     };
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:31:9
    |
 LL |       let _ = if true {
@@ -75,9 +75,9 @@ LL | |     } else {
 LL | |         10u32;
    | |         ^^^^^^ expected `i32`, found `()`
 LL | |     };
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:37:9
    |
 LL |       let _ = if true {
@@ -88,11 +88,11 @@ LL | |     } else {
 LL |           11u32
    |           ^^^^^ expected `()`, found `u32`
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-else-type-mismatch.rs:42:12
    |
 LL |       let _ = if true {
-   |               ------- if and else have incompatible types
+   |               ------- `if` and `else` have incompatible types
 LL |           12i32
    |           ----- expected because of this
 LL |       } else {
diff --git a/src/test/ui/if/if-branch-types.rs b/src/test/ui/if/if-branch-types.rs
index 5c693194a76..c125ba30606 100644
--- a/src/test/ui/if/if-branch-types.rs
+++ b/src/test/ui/if/if-branch-types.rs
@@ -1,5 +1,5 @@
 fn main() {
     let x = if true { 10i32 } else { 10u32 };
-    //~^ ERROR if and else have incompatible types
+    //~^ ERROR `if` and `else` have incompatible types
     //~| expected `i32`, found `u32`
 }
diff --git a/src/test/ui/if/if-branch-types.stderr b/src/test/ui/if/if-branch-types.stderr
index b5eacf5860f..14f02163a83 100644
--- a/src/test/ui/if/if-branch-types.stderr
+++ b/src/test/ui/if/if-branch-types.stderr
@@ -1,4 +1,4 @@
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-branch-types.rs:2:38
    |
 LL |     let x = if true { 10i32 } else { 10u32 };
diff --git a/src/test/ui/if/if-let-arm-types.rs b/src/test/ui/if/if-let-arm-types.rs
index cae4f0974c6..1e8260a017d 100644
--- a/src/test/ui/if/if-let-arm-types.rs
+++ b/src/test/ui/if/if-let-arm-types.rs
@@ -1,11 +1,11 @@
 fn main() {
     if let Some(b) = None {
-        //~^ NOTE if and else have incompatible types
+        //~^ NOTE `if` and `else` have incompatible types
         ()
         //~^ NOTE expected because of this
     } else {
         1
     };
-    //~^^ ERROR: if and else have incompatible types
+    //~^^ ERROR: `if` and `else` have incompatible types
     //~| NOTE expected `()`, found integer
 }
diff --git a/src/test/ui/if/if-let-arm-types.stderr b/src/test/ui/if/if-let-arm-types.stderr
index da93dfc9995..b40a0f479d3 100644
--- a/src/test/ui/if/if-let-arm-types.stderr
+++ b/src/test/ui/if/if-let-arm-types.stderr
@@ -1,4 +1,4 @@
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/if-let-arm-types.rs:7:9
    |
 LL | /     if let Some(b) = None {
@@ -10,7 +10,7 @@ LL | |     } else {
 LL | |         1
    | |         ^ expected `()`, found integer
 LL | |     };
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/if/if-without-else-as-fn-expr.rs b/src/test/ui/if/if-without-else-as-fn-expr.rs
index 826371be35f..19fbfb27ba6 100644
--- a/src/test/ui/if/if-without-else-as-fn-expr.rs
+++ b/src/test/ui/if/if-without-else-as-fn-expr.rs
@@ -2,14 +2,14 @@ fn foo(bar: usize) -> usize {
     if bar % 5 == 0 {
         return 3;
     }
-    //~^^^ ERROR if may be missing an else clause
+    //~^^^ ERROR `if` may be missing an `else` clause
 }
 
 fn foo2(bar: usize) -> usize {
     let x: usize = if bar % 5 == 0 {
         return 3;
     };
-    //~^^^ ERROR if may be missing an else clause
+    //~^^^ ERROR `if` may be missing an `else` clause
     x
 }
 
@@ -17,21 +17,21 @@ fn foo3(bar: usize) -> usize {
     if bar % 5 == 0 {
         3
     }
-    //~^^^ ERROR if may be missing an else clause
+    //~^^^ ERROR `if` may be missing an `else` clause
 }
 
 fn foo_let(bar: usize) -> usize {
     if let 0 = 1 {
         return 3;
     }
-    //~^^^ ERROR if may be missing an else clause
+    //~^^^ ERROR `if` may be missing an `else` clause
 }
 
 fn foo2_let(bar: usize) -> usize {
     let x: usize = if let 0 = 1 {
         return 3;
     };
-    //~^^^ ERROR if may be missing an else clause
+    //~^^^ ERROR `if` may be missing an `else` clause
     x
 }
 
@@ -39,7 +39,7 @@ fn foo3_let(bar: usize) -> usize {
     if let 0 = 1 {
         3
     }
-    //~^^^ ERROR if may be missing an else clause
+    //~^^^ ERROR `if` may be missing an `else` clause
 }
 
 // FIXME(60254): deduplicate first error in favor of second.
diff --git a/src/test/ui/if/if-without-else-as-fn-expr.stderr b/src/test/ui/if/if-without-else-as-fn-expr.stderr
index 9c7e7002360..4daf27493c1 100644
--- a/src/test/ui/if/if-without-else-as-fn-expr.stderr
+++ b/src/test/ui/if/if-without-else-as-fn-expr.stderr
@@ -1,4 +1,4 @@
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/if-without-else-as-fn-expr.rs:2:5
    |
 LL |   fn foo(bar: usize) -> usize {
@@ -11,7 +11,7 @@ LL | |     }
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/if-without-else-as-fn-expr.rs:9:20
    |
 LL |       let x: usize = if bar % 5 == 0 {
@@ -25,7 +25,7 @@ LL | |     };
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/if-without-else-as-fn-expr.rs:17:5
    |
 LL |   fn foo3(bar: usize) -> usize {
@@ -38,7 +38,7 @@ LL | |     }
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/if-without-else-as-fn-expr.rs:24:5
    |
 LL |   fn foo_let(bar: usize) -> usize {
@@ -51,7 +51,7 @@ LL | |     }
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/if-without-else-as-fn-expr.rs:31:20
    |
 LL |       let x: usize = if let 0 = 1 {
@@ -65,7 +65,7 @@ LL | |     };
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/if-without-else-as-fn-expr.rs:39:5
    |
 LL |   fn foo3_let(bar: usize) -> usize {
diff --git a/src/test/ui/if/if-without-else-result.rs b/src/test/ui/if/if-without-else-result.rs
index e5fb7b26321..cf84a99e53f 100644
--- a/src/test/ui/if/if-without-else-result.rs
+++ b/src/test/ui/if/if-without-else-result.rs
@@ -1,6 +1,6 @@
 fn main() {
     let a = if true { true };
-    //~^ ERROR if may be missing an else clause [E0317]
+    //~^ ERROR `if` may be missing an `else` clause [E0317]
     //~| expected `()`, found `bool`
     println!("{}", a);
 }
diff --git a/src/test/ui/if/if-without-else-result.stderr b/src/test/ui/if/if-without-else-result.stderr
index 66a8185774e..821635d3768 100644
--- a/src/test/ui/if/if-without-else-result.stderr
+++ b/src/test/ui/if/if-without-else-result.stderr
@@ -1,4 +1,4 @@
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/if-without-else-result.rs:2:13
    |
 LL |     let a = if true { true };
diff --git a/src/test/ui/issues/issue-11319.rs b/src/test/ui/issues/issue-11319.rs
index 8c2bafe63bd..ab69ab250ff 100644
--- a/src/test/ui/issues/issue-11319.rs
+++ b/src/test/ui/issues/issue-11319.rs
@@ -6,7 +6,7 @@ fn main() {
         Some(2) => true,
         //~^ NOTE this is found to be of type `bool`
         None    => (),
-        //~^ ERROR match arms have incompatible types
+        //~^ ERROR `match` arms have incompatible types
         //~| NOTE expected `bool`, found `()`
         _       => true
     }
diff --git a/src/test/ui/issues/issue-11319.stderr b/src/test/ui/issues/issue-11319.stderr
index 7663a32883c..fc44205e81e 100644
--- a/src/test/ui/issues/issue-11319.stderr
+++ b/src/test/ui/issues/issue-11319.stderr
@@ -1,4 +1,4 @@
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/issue-11319.rs:8:20
    |
 LL | /     match Some(10) {
diff --git a/src/test/ui/issues/issue-17728.nll.stderr b/src/test/ui/issues/issue-17728.nll.stderr
index ef193ad85bf..d515cf451c4 100644
--- a/src/test/ui/issues/issue-17728.nll.stderr
+++ b/src/test/ui/issues/issue-17728.nll.stderr
@@ -1,4 +1,4 @@
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/issue-17728.rs:109:14
    |
 LL | /     match to_parse {
diff --git a/src/test/ui/issues/issue-17728.rs b/src/test/ui/issues/issue-17728.rs
index 15cea1d609d..bec52d87d29 100644
--- a/src/test/ui/issues/issue-17728.rs
+++ b/src/test/ui/issues/issue-17728.rs
@@ -108,7 +108,7 @@ fn str_to_direction(to_parse: &str) -> RoomDirection {
         "down" => RoomDirection::Down,
         _ => None
     }
-        //~^^ ERROR match arms have incompatible types
+        //~^^ ERROR `match` arms have incompatible types
 }
 
 fn main() {
diff --git a/src/test/ui/issues/issue-17728.stderr b/src/test/ui/issues/issue-17728.stderr
index 527168dbe6c..2f9ae63aa41 100644
--- a/src/test/ui/issues/issue-17728.stderr
+++ b/src/test/ui/issues/issue-17728.stderr
@@ -9,7 +9,7 @@ LL |     fn attemptTraverse(&self, room: &Room, directionStr: &str) -> Result<&R
 LL |             Some(entry) => Ok(entry),
    |                            ^^^^^^^^^ ...but data from `room` is returned here
 
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/issue-17728.rs:109:14
    |
 LL | /     match to_parse {
diff --git a/src/test/ui/issues/issue-19991.rs b/src/test/ui/issues/issue-19991.rs
index 62d5a6de760..0f3f83001d3 100644
--- a/src/test/ui/issues/issue-19991.rs
+++ b/src/test/ui/issues/issue-19991.rs
@@ -1,8 +1,8 @@
 // Test if the sugared if-let construct correctly prints "missing an else clause" when an else
-// clause does not exist, instead of the unsympathetic "match arms have incompatible types"
+// clause does not exist, instead of the unsympathetic "`match` arms have incompatible types"
 
 fn main() {
-    if let Some(homura) = Some("madoka") { //~  ERROR missing an else clause
+    if let Some(homura) = Some("madoka") { //~  ERROR missing an `else` clause
                                            //~| expected `()`, found integer
         765
     };
diff --git a/src/test/ui/issues/issue-19991.stderr b/src/test/ui/issues/issue-19991.stderr
index b78f4a6d293..6e92be87a02 100644
--- a/src/test/ui/issues/issue-19991.stderr
+++ b/src/test/ui/issues/issue-19991.stderr
@@ -1,4 +1,4 @@
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/issue-19991.rs:5:5
    |
 LL | /     if let Some(homura) = Some("madoka") {
diff --git a/src/test/ui/issues/issue-24036.rs b/src/test/ui/issues/issue-24036.rs
index 2f501b941b5..bd82f95c9ef 100644
--- a/src/test/ui/issues/issue-24036.rs
+++ b/src/test/ui/issues/issue-24036.rs
@@ -10,7 +10,7 @@ fn closure_from_match() {
         2 => |c| c - 1,
         _ => |c| c - 1
     };
-    //~^^^ ERROR match arms have incompatible types
+    //~^^^ ERROR `match` arms have incompatible types
 }
 
 fn main() { }
diff --git a/src/test/ui/issues/issue-24036.stderr b/src/test/ui/issues/issue-24036.stderr
index 04817f2596a..b0e729a59eb 100644
--- a/src/test/ui/issues/issue-24036.stderr
+++ b/src/test/ui/issues/issue-24036.stderr
@@ -9,7 +9,7 @@ LL |     x = |c| c + 1;
    = note: no two closures, even if identical, have the same type
    = help: consider boxing your closure and/or using it as a trait object
 
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/issue-24036.rs:10:14
    |
 LL |       let x = match 1usize {
diff --git a/src/test/ui/issues/issue-4201.rs b/src/test/ui/issues/issue-4201.rs
index 2d655e4b7e7..1f292229fd6 100644
--- a/src/test/ui/issues/issue-4201.rs
+++ b/src/test/ui/issues/issue-4201.rs
@@ -2,7 +2,7 @@ fn main() {
     let a = if true {
         0
     } else if false {
-//~^ ERROR if may be missing an else clause
+//~^ ERROR `if` may be missing an `else` clause
 //~| expected `()`, found integer
         1
     };
diff --git a/src/test/ui/issues/issue-4201.stderr b/src/test/ui/issues/issue-4201.stderr
index aacc426783d..bc638ddf55b 100644
--- a/src/test/ui/issues/issue-4201.stderr
+++ b/src/test/ui/issues/issue-4201.stderr
@@ -1,4 +1,4 @@
-error[E0317]: if may be missing an else clause
+error[E0317]: `if` may be missing an `else` clause
   --> $DIR/issue-4201.rs:4:12
    |
 LL |       } else if false {
diff --git a/src/test/ui/issues/issue-9575.rs b/src/test/ui/issues/issue-9575.rs
index bac4ac1d208..06b252990b6 100644
--- a/src/test/ui/issues/issue-9575.rs
+++ b/src/test/ui/issues/issue-9575.rs
@@ -2,6 +2,6 @@
 
 #[start]
 fn start(argc: isize, argv: *const *const u8, crate_map: *const u8) -> isize {
-    //~^ start function has wrong type
+    //~^ `#[start]` function has wrong type
    0
 }
diff --git a/src/test/ui/issues/issue-9575.stderr b/src/test/ui/issues/issue-9575.stderr
index 3e3678a23f7..5b8ce84a071 100644
--- a/src/test/ui/issues/issue-9575.stderr
+++ b/src/test/ui/issues/issue-9575.stderr
@@ -1,4 +1,4 @@
-error[E0308]: start function has wrong type
+error[E0308]: `#[start]` function has wrong type
   --> $DIR/issue-9575.rs:4:1
    |
 LL | fn start(argc: isize, argv: *const *const u8, crate_map: *const u8) -> isize {
diff --git a/src/test/ui/lub-glb/old-lub-glb-hr.rs b/src/test/ui/lub-glb/old-lub-glb-hr.rs
index 6bf1fd41d77..bc7b787cd65 100644
--- a/src/test/ui/lub-glb/old-lub-glb-hr.rs
+++ b/src/test/ui/lub-glb/old-lub-glb-hr.rs
@@ -13,7 +13,7 @@ fn foo(
 ) {
     let z = match 22 {
         0 => x,
-        _ => y, //~ ERROR match arms have incompatible types
+        _ => y, //~ ERROR `match` arms have incompatible types
     };
 }
 
diff --git a/src/test/ui/lub-glb/old-lub-glb-hr.stderr b/src/test/ui/lub-glb/old-lub-glb-hr.stderr
index 1dce9df96df..6d5d5117469 100644
--- a/src/test/ui/lub-glb/old-lub-glb-hr.stderr
+++ b/src/test/ui/lub-glb/old-lub-glb-hr.stderr
@@ -1,4 +1,4 @@
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/old-lub-glb-hr.rs:16:14
    |
 LL |       let z = match 22 {
diff --git a/src/test/ui/lub-glb/old-lub-glb-object.rs b/src/test/ui/lub-glb/old-lub-glb-object.rs
index f303c07e6d7..63bbae59991 100644
--- a/src/test/ui/lub-glb/old-lub-glb-object.rs
+++ b/src/test/ui/lub-glb/old-lub-glb-object.rs
@@ -9,7 +9,7 @@ fn foo(
 ) {
     let z = match 22 {
         0 => x,
-        _ => y, //~ ERROR match arms have incompatible types
+        _ => y, //~ ERROR `match` arms have incompatible types
     };
 }
 
diff --git a/src/test/ui/lub-glb/old-lub-glb-object.stderr b/src/test/ui/lub-glb/old-lub-glb-object.stderr
index 18de7a40ee1..65c797f6b19 100644
--- a/src/test/ui/lub-glb/old-lub-glb-object.stderr
+++ b/src/test/ui/lub-glb/old-lub-glb-object.stderr
@@ -1,4 +1,4 @@
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/old-lub-glb-object.rs:12:14
    |
 LL |       let z = match 22 {
diff --git a/src/test/ui/main-wrong-type.rs b/src/test/ui/main-wrong-type.rs
index dac4d4ac9aa..31deba72af4 100644
--- a/src/test/ui/main-wrong-type.rs
+++ b/src/test/ui/main-wrong-type.rs
@@ -4,5 +4,5 @@ struct S {
 }
 
 fn main(foo: S) {
-//~^ ERROR: main function has wrong type [E0580]
+//~^ ERROR: `main` function has wrong type [E0580]
 }
diff --git a/src/test/ui/main-wrong-type.stderr b/src/test/ui/main-wrong-type.stderr
index e75d4d7acfd..43efaf884e3 100644
--- a/src/test/ui/main-wrong-type.stderr
+++ b/src/test/ui/main-wrong-type.stderr
@@ -1,4 +1,4 @@
-error[E0580]: main function has wrong type
+error[E0580]: `main` function has wrong type
   --> $DIR/main-wrong-type.rs:6:1
    |
 LL | fn main(foo: S) {
diff --git a/src/test/ui/match/match-arm-resolving-to-never.rs b/src/test/ui/match/match-arm-resolving-to-never.rs
index 8f54023305e..6ef249c0524 100644
--- a/src/test/ui/match/match-arm-resolving-to-never.rs
+++ b/src/test/ui/match/match-arm-resolving-to-never.rs
@@ -14,6 +14,6 @@ fn main() {
         E::C => 3,
         E::D => 4,
         E::E => unimplemented!(""),
-        E::F => "", //~ ERROR match arms have incompatible types
+        E::F => "", //~ ERROR `match` arms have incompatible types
     };
 }
diff --git a/src/test/ui/match/match-arm-resolving-to-never.stderr b/src/test/ui/match/match-arm-resolving-to-never.stderr
index 4482d5c6a79..3a723de9f6b 100644
--- a/src/test/ui/match/match-arm-resolving-to-never.stderr
+++ b/src/test/ui/match/match-arm-resolving-to-never.stderr
@@ -1,4 +1,4 @@
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/match-arm-resolving-to-never.rs:17:17
    |
 LL | /     match E::F {
diff --git a/src/test/ui/match/match-type-err-first-arm.rs b/src/test/ui/match/match-type-err-first-arm.rs
index d73c7e8402f..e9027eb2489 100644
--- a/src/test/ui/match/match-type-err-first-arm.rs
+++ b/src/test/ui/match/match-type-err-first-arm.rs
@@ -16,7 +16,7 @@ fn test_func2(n: i32) -> i32 {
     let x = match n { //~ NOTE `match` arms have incompatible types
         12 => 'b', //~ NOTE this is found to be of type `char`
         _ => 42,
-        //~^ ERROR match arms have incompatible types
+        //~^ ERROR `match` arms have incompatible types
         //~| NOTE expected `char`, found integer
     };
     x
@@ -32,7 +32,7 @@ fn test_func3(n: i32) -> i32 {
         6 => 'b',
         //~^ NOTE this and all prior arms are found to be of type `char`
         _ => 42,
-        //~^ ERROR match arms have incompatible types
+        //~^ ERROR `match` arms have incompatible types
         //~| NOTE expected `char`, found integer
     };
     x
@@ -44,7 +44,7 @@ fn test_func4() {
             x //~ NOTE this is found to be of type `u32`
         },
         None => {}
-        //~^ ERROR match arms have incompatible types
+        //~^ ERROR `match` arms have incompatible types
         //~| NOTE expected `u32`, found `()`
     };
 }
diff --git a/src/test/ui/match/match-type-err-first-arm.stderr b/src/test/ui/match/match-type-err-first-arm.stderr
index 1b3d8c61c86..fd489afa84d 100644
--- a/src/test/ui/match/match-type-err-first-arm.stderr
+++ b/src/test/ui/match/match-type-err-first-arm.stderr
@@ -7,7 +7,7 @@ LL |     match n {
 LL |         12 => 'b',
    |               ^^^ expected `i32`, found `char`
 
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/match-type-err-first-arm.rs:18:14
    |
 LL |       let x = match n {
@@ -21,7 +21,7 @@ LL | |
 LL | |     };
    | |_____- `match` arms have incompatible types
 
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/match-type-err-first-arm.rs:34:14
    |
 LL |       let x = match n {
@@ -40,7 +40,7 @@ LL | |
 LL | |     };
    | |_____- `match` arms have incompatible types
 
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/match-type-err-first-arm.rs:46:17
    |
 LL | /     match Some(0u32) {
diff --git a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.rs b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.rs
index 58109be447e..a80e5df1a26 100644
--- a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.rs
+++ b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.rs
@@ -29,7 +29,7 @@ fn qux() -> impl std::fmt::Display {
         0i32
     } else {
         1u32
-        //~^ ERROR if and else have incompatible types
+        //~^ ERROR `if` and `else` have incompatible types
     }
 }
 
diff --git a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr
index d5ea2ba39a9..27b86007451 100644
--- a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr
+++ b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr
@@ -34,7 +34,7 @@ LL |     } else {
 LL |         1u32
    |         ^^^^ expected `i32`, found `u32`
 
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:31:9
    |
 LL | /     if false {
@@ -45,7 +45,7 @@ LL | |         1u32
    | |         ^^^^ expected `i32`, found `u32`
 LL | |
 LL | |     }
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
 
 error[E0308]: mismatched types
   --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:39:14
diff --git a/src/test/ui/regions/region-invariant-static-error-reporting.stderr b/src/test/ui/regions/region-invariant-static-error-reporting.stderr
index 381bad4210f..750cc3566e0 100644
--- a/src/test/ui/regions/region-invariant-static-error-reporting.stderr
+++ b/src/test/ui/regions/region-invariant-static-error-reporting.stderr
@@ -1,4 +1,4 @@
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/region-invariant-static-error-reporting.rs:17:9
    |
 LL |       let bad = if x.is_some() {
@@ -9,7 +9,7 @@ LL | |     } else {
 LL | |         mk_static()
    | |         ^^^^^^^^^^^ lifetime mismatch
 LL | |     };
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
    |
    = note: expected struct `Invariant<'a>`
               found struct `Invariant<'static>`
diff --git a/src/test/ui/str/str-array-assignment.rs b/src/test/ui/str/str-array-assignment.rs
index 4a78ed53ae1..323eefb381a 100644
--- a/src/test/ui/str/str-array-assignment.rs
+++ b/src/test/ui/str/str-array-assignment.rs
@@ -1,7 +1,7 @@
 fn main() {
   let s = "abc";
   let t = if true { s[..2] } else { s };
-  //~^ ERROR if and else have incompatible types
+  //~^ ERROR `if` and `else` have incompatible types
   let u: &str = if true { s[..2] } else { s };
   //~^ ERROR mismatched types
   let v = s[..2];
diff --git a/src/test/ui/str/str-array-assignment.stderr b/src/test/ui/str/str-array-assignment.stderr
index a133c69eeef..cc767de3845 100644
--- a/src/test/ui/str/str-array-assignment.stderr
+++ b/src/test/ui/str/str-array-assignment.stderr
@@ -1,4 +1,4 @@
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/str-array-assignment.rs:3:37
    |
 LL |   let t = if true { s[..2] } else { s };
diff --git a/src/test/ui/suggestions/opaque-type-error.rs b/src/test/ui/suggestions/opaque-type-error.rs
index 979bb60d48c..5e114740314 100644
--- a/src/test/ui/suggestions/opaque-type-error.rs
+++ b/src/test/ui/suggestions/opaque-type-error.rs
@@ -17,7 +17,7 @@ async fn thing() -> Result<(), ()> {
     if true {
         thing_one()
     } else {
-        thing_two() //~ ERROR if and else have incompatible types
+        thing_two() //~ ERROR `if` and `else` have incompatible types
     }.await
 }
 
diff --git a/src/test/ui/suggestions/opaque-type-error.stderr b/src/test/ui/suggestions/opaque-type-error.stderr
index e7bf84a4113..1465b9e49ef 100644
--- a/src/test/ui/suggestions/opaque-type-error.stderr
+++ b/src/test/ui/suggestions/opaque-type-error.stderr
@@ -1,4 +1,4 @@
-error[E0308]: if and else have incompatible types
+error[E0308]: `if` and `else` have incompatible types
   --> $DIR/opaque-type-error.rs:20:9
    |
 LL | /     if true {
@@ -8,7 +8,7 @@ LL | |     } else {
 LL | |         thing_two()
    | |         ^^^^^^^^^^^ expected opaque type, found a different opaque type
 LL | |     }.await
-   | |_____- if and else have incompatible types
+   | |_____- `if` and `else` have incompatible types
    |
    = note:     expected type `impl std::future::Future` (opaque type at <$DIR/opaque-type-error.rs:8:19>)
            found opaque type `impl std::future::Future` (opaque type at <$DIR/opaque-type-error.rs:12:19>)
diff --git a/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs
index e23c0d0a40a..c39ab954473 100644
--- a/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs
+++ b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs
@@ -20,7 +20,7 @@ fn main() {
         // However, in #67273, we would delay the unification of this arm with the above
         // because we used the hitherto accumulated coercion as opposed to the "initial" type.
         2 => i = 1,
-        //~^ ERROR match arms have incompatible types
+        //~^ ERROR `match` arms have incompatible types
 
         _ => (),
     }
diff --git a/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.stderr b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.stderr
index 3547285542a..a431fe89c23 100644
--- a/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.stderr
+++ b/src/test/ui/type/type-check/issue-67273-assignment-match-prior-arm-bool-expected-unit.stderr
@@ -1,4 +1,4 @@
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/issue-67273-assignment-match-prior-arm-bool-expected-unit.rs:22:14
    |
 LL | /     match i {
diff --git a/src/test/ui/wf/wf-unsafe-trait-obj-match.stderr b/src/test/ui/wf/wf-unsafe-trait-obj-match.stderr
index d5799ccc834..594fad41385 100644
--- a/src/test/ui/wf/wf-unsafe-trait-obj-match.stderr
+++ b/src/test/ui/wf/wf-unsafe-trait-obj-match.stderr
@@ -1,4 +1,4 @@
-error[E0308]: match arms have incompatible types
+error[E0308]: `match` arms have incompatible types
   --> $DIR/wf-unsafe-trait-obj-match.rs:23:17
    |
 LL | /     match opt() {