Further tweak the type shortening logic

Author: estebank

compiler/rustc_middle/src/ty/error.rs

@@ -986,13 +986,14 @@ fn foo(&self) -> Self::T { String::new() }
     }
 
     pub fn short_ty_string(self, ty: Ty<'tcx>) -> (String, Option<PathBuf>) {
-        let length_limit = self.sess.diagnostic_width().saturating_sub(20);
+        let width = self.sess.diagnostic_width();
+        let length_limit = width.saturating_sub(30);
         let mut type_limit = 50;
         let regular = FmtPrinter::new(self, hir::def::Namespace::TypeNS)
             .pretty_print_type(ty)
             .expect("could not write to `String`")
             .into_buffer();
-        if regular.len() <= length_limit {
+        if regular.len() <= width {
             return (regular, None);
         }
         let mut short;

src/test/ui/diagnostic-width/long-E0308.stderr

@@ -18,7 +18,7 @@ LL | |          ))))))))))))))))))))))))))))))
 LL | |      ))))))))))))))))))))))))))))));
    | |___________________________________^ expected struct `Atype`, found enum `Result`
    |
-   = note: expected struct `Atype<Btype<Ctype<..., ...>, ...>, ...>`
+   = note: expected struct `Atype<Btype<..., ...>, ...>`
            the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
                 found enum `Result<Result<..., ...>, ...>`
            the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
@@ -34,7 +34,7 @@ LL | |         ))))))))))))))))))))))))))))))
 LL | |     ))))))))))))))))))))))));
    | |____________________________^ expected enum `Option`, found enum `Result`
    |
-   = note: expected enum `Option<Result<Option<Option<...>>, ...>>`
+   = note: expected enum `Option<Result<..., ...>>`
            the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
               found enum `Result<Result<..., ...>, ...>`
            the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
@@ -54,7 +54,7 @@ LL | |     > = ();
    | |_____|
    |       expected due to this
    |
-   = note: expected struct `Atype<Btype<Ctype<..., ...>, ...>, ...>`
+   = note: expected struct `Atype<Btype<..., ...>, ...>`
            the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
            found unit type `()`
 

src/test/ui/error-codes/E0275.stderr

@@ -5,7 +5,7 @@ LL | impl<T> Foo for T where Bar<T>: Foo {}
    |                                 ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`E0275`)
-note: required for `Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<...>>>>>>>>>>>>>>>>>>>>>>>` to implement `Foo`
+note: required for `Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<...>>>>>>>>>>>>>>>>>>>>>` to implement `Foo`
   --> $DIR/E0275.rs:6:9
    |
 LL | impl<T> Foo for T where Bar<T>: Foo {}

src/test/ui/issues/issue-20413.stderr

@@ -14,7 +14,7 @@ LL | impl<T> Foo for T where NoData<T>: Foo {
    |                                    ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
-note: required for `NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<...>>>>>>>>>>>>>>` to implement `Foo`
+note: required for `NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<...>>>>>>>>>>>>>` to implement `Foo`
   --> $DIR/issue-20413.rs:9:9
    |
 LL | impl<T> Foo for T where NoData<T>: Foo {
@@ -30,13 +30,13 @@ LL | impl<T> Bar for T where EvenLessData<T>: Baz {
    |                                          ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
-note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>>>` to implement `Bar`
+note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>>` to implement `Bar`
   --> $DIR/issue-20413.rs:28:9
    |
 LL | impl<T> Bar for T where EvenLessData<T>: Baz {
    |         ^^^     ^
    = note: the full type name has been written to '$TEST_BUILD_DIR/issues/issue-20413/issue-20413.long-type-hash.txt'
-note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>>>` to implement `Baz`
+note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>>` to implement `Baz`
   --> $DIR/issue-20413.rs:35:9
    |
 LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
@@ -52,13 +52,13 @@ LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
    |                                          ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
-note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>>>` to implement `Baz`
+note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>>` to implement `Baz`
   --> $DIR/issue-20413.rs:35:9
    |
 LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
    |         ^^^     ^
    = note: the full type name has been written to '$TEST_BUILD_DIR/issues/issue-20413/issue-20413.long-type-hash.txt'
-note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>>>` to implement `Bar`
+note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>>` to implement `Bar`
   --> $DIR/issue-20413.rs:28:9
    |
 LL | impl<T> Bar for T where EvenLessData<T>: Baz {

src/test/ui/recursion/issue-83150.stderr

@@ -12,7 +12,7 @@ LL |     func(&mut iter.map(|x| x + 1))
 error[E0275]: overflow evaluating the requirement `Map<&mut Map<&mut Map<&mut Map<..., ...>, ...>, ...>, ...>: Iterator`
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_83150`)
-   = note: required for `&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut ..., ...>, ...>, ...>, ...>, ...>, ...>, ...>` to implement `Iterator`
+   = note: required for `&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<..., ...>, ...>, ...>, ...>, ...>, ...>, ...>` to implement `Iterator`
    = note: the full type name has been written to '$TEST_BUILD_DIR/recursion/issue-83150/issue-83150.long-type-hash.txt'
 
 error: aborting due to previous error; 1 warning emitted