Strip code to the left and right in diagnostics for long lines

Cargo.lock

@@ -3219,6 +3219,7 @@ dependencies = [
  "rustc_data_structures",
  "serialize",
  "syntax_pos",
+ "term_size",
  "termcolor",
  "unicode-width",
 ]
@@ -4090,6 +4091,17 @@ dependencies = [
  "winapi 0.3.6",
 ]
 
+[[package]]
+name = "term_size"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e5b9a66db815dcfd2da92db471106457082577c3c278d4138ab3e3b4e189327"
+dependencies = [
+ "kernel32-sys",
+ "libc",
+ "winapi 0.2.8",
+]
+
 [[package]]
 name = "termcolor"
 version = "1.0.4"

src/librustc/session/config.rs

@@ -1292,6 +1292,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "show macro backtraces even for non-local macros"),
     teach: bool = (false, parse_bool, [TRACKED],
         "show extended diagnostic help"),
+    terminal_width: Option<usize> = (None, parse_opt_uint, [UNTRACKED],
+        "set the current terminal width"),
     continue_parse_after_error: bool = (false, parse_bool, [TRACKED],
         "attempt to recover from parse errors (experimental)"),
     dep_tasks: bool = (false, parse_bool, [UNTRACKED],

src/librustc/session/mod.rs

@@ -1055,13 +1055,15 @@ fn default_emitter(
                         Some(source_map.clone()),
                         short,
                         sopts.debugging_opts.teach,
+                        sopts.debugging_opts.terminal_width,
                     ),
                     Some(dst) => EmitterWriter::new(
                         dst,
                         Some(source_map.clone()),
                         short,
                         false, // no teach messages when writing to a buffer
                         false, // no colors when writing to a buffer
+                        None,  // no terminal width
                     ),
                 };
                 Box::new(emitter.ui_testing(sopts.debugging_opts.ui_testing))
@@ -1375,7 +1377,7 @@ pub fn early_error(output: config::ErrorOutputType, msg: &str) -> ! {
     let emitter: Box<dyn Emitter + sync::Send> = match output {
         config::ErrorOutputType::HumanReadable(kind) => {
             let (short, color_config) = kind.unzip();
-            Box::new(EmitterWriter::stderr(color_config, None, short, false))
+            Box::new(EmitterWriter::stderr(color_config, None, short, false, None))
         }
         config::ErrorOutputType::Json { pretty, json_rendered } =>
             Box::new(JsonEmitter::basic(pretty, json_rendered)),
@@ -1389,7 +1391,7 @@ pub fn early_warn(output: config::ErrorOutputType, msg: &str) {
     let emitter: Box<dyn Emitter + sync::Send> = match output {
         config::ErrorOutputType::HumanReadable(kind) => {
             let (short, color_config) = kind.unzip();
-            Box::new(EmitterWriter::stderr(color_config, None, short, false))
+            Box::new(EmitterWriter::stderr(color_config, None, short, false, None))
         }
         config::ErrorOutputType::Json { pretty, json_rendered } =>
             Box::new(JsonEmitter::basic(pretty, json_rendered)),

src/librustc_driver/lib.rs

@@ -1135,11 +1135,13 @@ pub fn report_ices_to_stderr_if_any<F: FnOnce() -> R, R>(f: F) -> Result<R, Erro
             // Thread panicked without emitting a fatal diagnostic
             eprintln!("");
 
-            let emitter =
-                Box::new(errors::emitter::EmitterWriter::stderr(errors::ColorConfig::Auto,
-                                                                None,
-                                                                false,
-                                                                false));
+            let emitter = Box::new(errors::emitter::EmitterWriter::stderr(
+                errors::ColorConfig::Auto,
+                None,
+                false,
+                false,
+                None,
+            ));
             let handler = errors::Handler::with_emitter(true, None, emitter);
 
             // a .span_bug or .bug call has already printed what

src/librustc_errors/Cargo.toml

@@ -18,3 +18,4 @@ unicode-width = "0.1.4"
 atty = "0.2"
 termcolor = "1.0"
 annotate-snippets = "0.6.1"
+term_size = "0.3.1"

src/librustc_errors/lib.rs

@@ -383,7 +383,7 @@ impl Handler {
                                       cm: Option<Lrc<SourceMapperDyn>>,
                                       flags: HandlerFlags)
                                       -> Handler {
-        let emitter = Box::new(EmitterWriter::stderr(color_config, cm, false, false));
+        let emitter = Box::new(EmitterWriter::stderr(color_config, cm, false, false, None));
         Handler::with_emitter_and_flags(emitter, flags)
     }
 

src/librustdoc/core.rs

@@ -193,6 +193,7 @@ pub fn new_handler(error_format: ErrorOutputType,
                     source_map.map(|cm| cm as _),
                     short,
                     sessopts.debugging_opts.teach,
+                    sessopts.debugging_opts.terminal_width,
                 ).ui_testing(ui_testing)
             )
         },

src/librustdoc/test.rs

@@ -427,7 +427,7 @@ pub fn make_test(s: &str,
         // 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);
+        let emitter = EmitterWriter::new(box io::sink(), None, false, false, false, None);
         // 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);

src/libsyntax/json.rs

@@ -219,7 +219,7 @@ impl Diagnostic {
         }
         let buf = BufWriter::default();
         let output = buf.clone();
-        je.json_rendered.new_emitter(Box::new(buf), Some(je.sm.clone()), false)
+        je.json_rendered.new_emitter(Box::new(buf), Some(je.sm.clone()), false, None)
             .ui_testing(je.ui_testing).emit_diagnostic(db);
         let output = Arc::try_unwrap(output.0).unwrap().into_inner().unwrap();
         let output = String::from_utf8(output).unwrap();

src/libsyntax/parse/lexer/tests.rs

@@ -10,7 +10,14 @@ use errors::{Handler, emitter::EmitterWriter};
 use syntax_pos::{BytePos, Span};
 
 fn mk_sess(sm: Lrc<SourceMap>) -> ParseSess {
-    let emitter = EmitterWriter::new(Box::new(io::sink()), Some(sm.clone()), false, false, false);
+    let emitter = EmitterWriter::new(
+        Box::new(io::sink()),
+        Some(sm.clone()),
+        false,
+        false,
+        false,
+        None,
+    );
     ParseSess::with_span_handler(Handler::with_emitter(true, None, Box::new(emitter)), sm)
 }
 
@@ -28,10 +35,11 @@ fn t1() {
     with_default_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
-        let mut string_reader = setup(&sm,
-                                    &sh,
-                                    "/* my source file */ fn main() { println!(\"zebra\"); }\n"
-                                        .to_string());
+        let mut string_reader = setup(
+            &sm,
+            &sh,
+            "/* my source file */ fn main() { println!(\"zebra\"); }\n".to_string(),
+        );
         assert_eq!(string_reader.next_token(), token::Comment);
         assert_eq!(string_reader.next_token(), token::Whitespace);
         let tok1 = string_reader.next_token();
@@ -127,8 +135,10 @@ fn character_a() {
     with_default_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
-        assert_eq!(setup(&sm, &sh, "'a'".to_string()).next_token(),
-                    mk_lit(token::Char, "a", None));
+        assert_eq!(
+            setup(&sm, &sh, "'a'".to_string()).next_token(),
+            mk_lit(token::Char, "a", None),
+        );
     })
 }
 
@@ -137,8 +147,10 @@ fn character_space() {
     with_default_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
-        assert_eq!(setup(&sm, &sh, "' '".to_string()).next_token(),
-                    mk_lit(token::Char, " ", None));
+        assert_eq!(
+            setup(&sm, &sh, "' '".to_string()).next_token(),
+            mk_lit(token::Char, " ", None),
+        );
     })
 }
 
@@ -147,8 +159,10 @@ fn character_escaped() {
     with_default_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
-        assert_eq!(setup(&sm, &sh, "'\\n'".to_string()).next_token(),
-                    mk_lit(token::Char, "\\n", None));
+        assert_eq!(
+            setup(&sm, &sh, "'\\n'".to_string()).next_token(),
+            mk_lit(token::Char, "\\n", None),
+        );
     })
 }
 
@@ -157,8 +171,10 @@ fn lifetime_name() {
     with_default_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
-        assert_eq!(setup(&sm, &sh, "'abc".to_string()).next_token(),
-                    token::Lifetime(Symbol::intern("'abc")));
+        assert_eq!(
+            setup(&sm, &sh, "'abc".to_string()).next_token(),
+            token::Lifetime(Symbol::intern("'abc")),
+        );
     })
 }
 
@@ -167,8 +183,10 @@ fn raw_string() {
     with_default_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
-        assert_eq!(setup(&sm, &sh, "r###\"\"#a\\b\x00c\"\"###".to_string()).next_token(),
-                    mk_lit(token::StrRaw(3), "\"#a\\b\x00c\"", None));
+        assert_eq!(
+            setup(&sm, &sh, "r###\"\"#a\\b\x00c\"\"###".to_string()).next_token(),
+            mk_lit(token::StrRaw(3), "\"#a\\b\x00c\"", None),
+        );
     })
 }
 
@@ -179,11 +197,15 @@ fn literal_suffixes() {
         let sh = mk_sess(sm.clone());
         macro_rules! test {
             ($input: expr, $tok_type: ident, $tok_contents: expr) => {{
-                assert_eq!(setup(&sm, &sh, format!("{}suffix", $input)).next_token(),
-                            mk_lit(token::$tok_type, $tok_contents, Some("suffix")));
+                assert_eq!(
+                    setup(&sm, &sh, format!("{}suffix", $input)).next_token(),
+                    mk_lit(token::$tok_type, $tok_contents, Some("suffix")),
+                );
                 // with a whitespace separator:
-                assert_eq!(setup(&sm, &sh, format!("{} suffix", $input)).next_token(),
-                            mk_lit(token::$tok_type, $tok_contents, None));
+                assert_eq!(
+                    setup(&sm, &sh, format!("{} suffix", $input)).next_token(),
+                    mk_lit(token::$tok_type, $tok_contents, None),
+                );
             }}
         }
 
@@ -197,12 +219,18 @@ fn literal_suffixes() {
         test!("1.0", Float, "1.0");
         test!("1.0e10", Float, "1.0e10");
 
-        assert_eq!(setup(&sm, &sh, "2us".to_string()).next_token(),
-                    mk_lit(token::Integer, "2", Some("us")));
-        assert_eq!(setup(&sm, &sh, "r###\"raw\"###suffix".to_string()).next_token(),
-                    mk_lit(token::StrRaw(3), "raw", Some("suffix")));
-        assert_eq!(setup(&sm, &sh, "br###\"raw\"###suffix".to_string()).next_token(),
-                    mk_lit(token::ByteStrRaw(3), "raw", Some("suffix")));
+        assert_eq!(
+            setup(&sm, &sh, "2us".to_string()).next_token(),
+            mk_lit(token::Integer, "2", Some("us")),
+        );
+        assert_eq!(
+            setup(&sm, &sh, "r###\"raw\"###suffix".to_string()).next_token(),
+            mk_lit(token::StrRaw(3), "raw", Some("suffix")),
+        );
+        assert_eq!(
+            setup(&sm, &sh, "br###\"raw\"###suffix".to_string()).next_token(),
+            mk_lit(token::ByteStrRaw(3), "raw", Some("suffix")),
+        );
     })
 }
 

src/libsyntax/tests.rs

@@ -144,11 +144,14 @@ fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &
             println!("text: {:?}", source_map.span_to_snippet(span));
         }
 
-        let emitter = EmitterWriter::new(Box::new(Shared { data: output.clone() }),
-                                        Some(source_map.clone()),
-                                        false,
-                                        false,
-                                        false);
+        let emitter = EmitterWriter::new(
+            Box::new(Shared { data: output.clone() }),
+            Some(source_map.clone()),
+            false,
+            false,
+            false,
+            None,
+        );
         let handler = Handler::with_emitter(true, None, Box::new(emitter));
         handler.span_err(msp, "foo");
 

src/test/ui/inline-asm-bad-operand.stderr

@@ -37,8 +37,8 @@ LL |         asm!("mov sp, $0"::"r"(addr),
 error[E0669]: invalid value for constraint in inline assembly
   --> $DIR/inline-asm-bad-operand.rs:56:32
    |
-LL |                            "r"("hello e0669"));
-   |                                ^^^^^^^^^^^^^
+LL | ...                   "r"("hello e0669"));
+   |                           ^^^^^^^^^^^^^
 
 error: aborting due to 7 previous errors
 

src/test/ui/lint/lint-stability-deprecated.stderr

@@ -67,14 +67,14 @@ LL |         deprecated_unstable_text();
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:57:9
    |
-LL |         Trait::trait_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   Trait::trait_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:59:9
    |
-LL |         <Foo as Trait>::trait_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   <Foo as Trait>::trait_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::DeprecatedStruct': text
   --> $DIR/lint-stability-deprecated.rs:106:17
@@ -181,14 +181,14 @@ LL |         <Foo as Trait>::trait_deprecated_unstable(&foo);
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:155:9
    |
-LL |         Trait::trait_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   Trait::trait_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:157:9
    |
-LL |         <Foo as Trait>::trait_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   <Foo as Trait>::trait_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::DeprecatedTrait': text
   --> $DIR/lint-stability-deprecated.rs:185:10
@@ -421,20 +421,20 @@ LL |         <Foo>::trait_deprecated_unstable(&foo);
 warning: use of deprecated item 'lint_stability::MethodTester::method_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:53:13
    |
-LL |         foo.method_deprecated_unstable_text();
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   foo.method_deprecated_unstable_text();
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::MethodTester::method_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:54:9
    |
-LL |         Foo::method_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   Foo::method_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::MethodTester::method_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:55:9
    |
-LL |         <Foo>::method_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   <Foo>::method_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:56:13
@@ -445,8 +445,8 @@ LL |         foo.trait_deprecated_unstable_text();
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:58:9
    |
-LL |         <Foo>::trait_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   <Foo>::trait_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::DeprecatedStruct::i': text
   --> $DIR/lint-stability-deprecated.rs:107:13
@@ -505,8 +505,8 @@ LL |         foo.trait_deprecated_unstable_text();
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated_unstable_text': text
   --> $DIR/lint-stability-deprecated.rs:156:9
    |
-LL |         <Foo>::trait_deprecated_unstable_text(&foo);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | ...   <Foo>::trait_deprecated_unstable_text(&foo);
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'lint_stability::Trait::trait_deprecated': text
   --> $DIR/lint-stability-deprecated.rs:173:13

src/test/ui/regions/regions-name-undeclared.stderr

@@ -49,14 +49,14 @@ LL | fn fn_types(a: &'a isize,
 error[E0261]: use of undeclared lifetime name `'b`
   --> $DIR/regions-name-undeclared.rs:42:36
    |
-LL |                                   &'b isize,
-   |                                    ^^ undeclared lifetime
+LL | ...                   &'b isize,
+   |                        ^^ undeclared lifetime
 
 error[E0261]: use of undeclared lifetime name `'b`
   --> $DIR/regions-name-undeclared.rs:45:36
    |
-LL |                                   &'b isize)>,
-   |                                    ^^ undeclared lifetime
+LL | ...                   &'b isize)>,
+   |                        ^^ undeclared lifetime
 
 error[E0261]: use of undeclared lifetime name `'a`
   --> $DIR/regions-name-undeclared.rs:46:17

src/test/ui/terminal-width/non-whitespace-trimming-2.rs

@@ -0,0 +1,6 @@
+// ignore-tidy-linelength
+
+fn main() {
+    let _: usize = 0; let _: usize = 1; let _: usize = 2; let _: usize = 3; let _: usize = 4; let _: usize = 5; let _: usize = 6; let _: usize = 7; let _: usize = 8; let _: usize = 9; let _: usize = 10; let _: usize = 11; let _: usize = 12; let _: usize = 13; let _: usize = 14; let _: usize = 15; let _: () = 42; let _: usize = 0; let _: usize = 1; let _: usize = 2; let _: usize = 3; let _: usize = 4; let _: usize = 5; let _: usize = 6; let _: usize = 7; let _: usize = 8; let _: usize = 9; let _: usize = 10; let _: usize = 11; let _: usize = 12; let _: usize = 13; let _: usize = 14; let _: usize = 15;
+//~^ ERROR mismatched types
+}

src/test/ui/terminal-width/non-whitespace-trimming-2.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/non-whitespace-trimming-2.rs:4:311
+   |
+LL | ...; let _: usize = 14; let _: usize = 15; let _: () = 42; let _: usize = 0; let _: usize = 1; let _: usize = 2; let _: usize = 3; let _:...
+   |                                                        ^^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/terminal-width/non-whitespace-trimming-unicode.rs

@@ -0,0 +1,6 @@
+// ignore-tidy-linelength
+
+fn main() {
+    let _: &str = "🦀☀☁☂☃☄★☆☇☈☉☊☋☌☍☎☏☐☑☒☓  ☖☗☘☙☚☛☜☝☞☟☠☡☢☣☤☥☦☧☨☩☪☫☬☭☮☯☰☱☲☳☴☵☶☷☸☹☺☻☼☽☾☿♀♁♂♃♄♅♆♇♏♔♕♖♗♘♙♚♛♜♝♞♟♠♡♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳♴♵♶♷♸♹♺♻♼♽♾♿⚀⚁⚂⚃⚄⚅⚆⚈⚉4🦀☀☁☂☃☄★☆☇☈☉☊☋☌☍☎☏☐☑☒☓☖☗☘☙☚☛☜☝☞☟☠☡☢☣☤☥☦☧☨☩☪☫☬☭☮☯☰☱☲☳☴☵☶☷☸☹☺☻☼☽☾☿♀♁♂♃♄♅♆♇♏♔♕♖♗♘♙♚♛♜♝♞♟♠♡♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳♴♵♶♷♸♹♺♻♼♽♾♿⚀⚁⚂⚃⚄⚅⚆⚈⚉4🦀🦀☁☂☃☄★☆☇☈☉☊☋☌☍☎☏☐☑☒☓☖☗☘☙☚☛☜☝☞☟☠☡☢☣☤☥☦☧☨☩☪☫☬☭☮☯☰☱☲☳☴☵☶☷☸☹☺☻☼☽☾☿♀♁♂♃♄♅♆♇♏♔♕♖♗♘♙♚♛♜♝♞♟♠♡♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳♴♵♶♷♸♹♺♻♼♽♾♿⚀⚁⚂⚃⚄⚅⚆⚈⚉4"; let _: () = 42;  let _: &str = "🦀☀☁☂☃☄★☆☇☈☉☊☋☌☍☎☏☐☑☒☓  ☖☗☘☙☚☛☜☝☞☟☠☡☢☣☤☥☦☧☨☩☪☫☬☭☮☯☰☱☲☳☴☵☶☷☸☹☺☻☼☽☾☿♀♁♂♃♄♅♆♇♏♔♕♖♗♘♙♚♛♜♝♞♟♠♡♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳♴♵♶♷♸♹♺♻♼♽♾♿⚀⚁⚂⚃⚄⚅⚆⚈⚉4🦀☀☁☂☃☄★☆☇☈☉☊☋☌☍☎☏☐☑☒☓☖☗☘☙☚☛☜☝☞☟☠☡☢☣☤☥☦☧☨☩☪☫☬☭☮☯☰☱☲☳☴☵☶☷☸☹☺☻☼☽☾☿♀♁♂♃♄♅♆♇♏♔♕♖♗♘♙♚♛♜♝♞♟♠♡♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳♴♵♶♷♸♹♺♻♼♽♾♿⚀⚁⚂⚃⚄⚅⚆⚈⚉4🦀🦀☁☂☃☄★☆☇☈☉☊☋☌☍☎☏☐☑☒☓☖☗☘☙☚☛☜☝☞☟☠☡☢☣☤☥☦☧☨☩☪☫☬☭☮☯☰☱☲☳☴☵☶☷☸☹☺☻☼☽☾☿♀♁♂♃♄♅♆♇♏♔♕♖♗♘♙♚♛♜♝♞♟♠♡♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳♴♵♶♷♸♹♺♻♼♽♾♿⚀⚁⚂⚃⚄⚅⚆⚈⚉4";
+//~^ ERROR mismatched types
+}

src/test/ui/terminal-width/non-whitespace-trimming-unicode.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/non-whitespace-trimming-unicode.rs:4:415
+   |
+LL | ...♯♰♱♲♳♴♵♶♷♸♹♺♻♼♽♾♿⚀⚁⚂⚃⚄⚅⚆⚈⚉4"; let _: () = 42;  let _: &str = "🦀☀☁☂☃☄★☆☇☈☉☊☋☌☍☎☏☐☑☒☓  ☖☗☘☙☚☛☜☝☞☟☠☡☢☣☤☥☦☧☨☩☪☫☬☭☮☯☰☱☲☳☴☵☶☷☸☹☺☻☼☽☾☿♀♁♂♃♄♅♆...
+   |                                               ^^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/terminal-width/non-whitespace-trimming.rs

@@ -0,0 +1,6 @@
+// ignore-tidy-linelength
+
+fn main() {
+    let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = 42; let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = ();
+//~^ ERROR mismatched types
+}

src/test/ui/terminal-width/non-whitespace-trimming.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/non-whitespace-trimming.rs:4:241
+   |
+LL | ...) = (); let _: () = (); let _: () = (); let _: () = 42; let _: () = (); let _: () = (); let _: () = (); let _: () = (); let _: () = ()...
+   |                                                        ^^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/terminal-width/whitespace-trimming-2.rs

@@ -0,0 +1,8 @@
+// ignore-tidy-linelength
+
+fn foo() -> usize {
+                                                                                                                                                                                          ()
+//~^ ERROR mismatched types
+}
+
+fn main() {}

src/test/ui/terminal-width/whitespace-trimming-2.stderr

@@ -0,0 +1,14 @@
+error[E0308]: mismatched types
+  --> $DIR/whitespace-trimming-2.rs:4:187
+   |
+LL | ...-> usize {
+   |       ----- expected `usize` because of return type
+LL | ...                                                                                                                                                                                 ()
+   |                                                                                                                                                                                     ^^ expected usize, found ()
+   |
+   = note: expected type `usize`
+              found type `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/terminal-width/whitespace-trimming.rs

@@ -0,0 +1,6 @@
+// ignore-tidy-linelength
+
+fn main() {
+                                                                                                                                                                                    let _: () = 42;
+//~^ ERROR mismatched types
+}

src/test/ui/terminal-width/whitespace-trimming.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/whitespace-trimming.rs:4:193
+   |
+LL | ...                   let _: () = 42;
+   |                                   ^^ expected (), found integer
+   |
+   = note: expected type `()`
+              found type `{integer}`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.

src/tools/tidy/src/deps.rs

@@ -159,6 +159,7 @@ const WHITELIST: &[Crate<'_>] = &[
     Crate("termcolor"),
     Crate("terminon"),
     Crate("termion"),
+    Crate("term_size"),
     Crate("thread_local"),
     Crate("ucd-util"),
     Crate("unicode-width"),