Perform most diagnostic lookups in resolution_failure

Previously, these were spread throughout the codebase. This had two
drawbacks:

1. It caused the fast path to be slower: even if a link resolved,
rustdoc would still perform various lookups for the error diagnostic.
2. It was inconsistent and didn't always give all diagnostics (rust-lang#76925)

Now, diagnostics only perform expensive lookups in the error case.
Additionally, the error handling is much more consistent, both in
wording and behavior.

- Remove `CannotHaveAssociatedItems`, `NotInScope`, `NoAssocItem`, and `NotAVariant`
  in favor of the more general `NotResolved`

  `resolution_failure` will now look up which of the four above
  categories is relevant, instead of requiring the rest of the code to
  be consistent and accurate in which it picked.

- Remove unnecessary lookups throughout the intra-doc link pass. These
are now done by `resolution_failure`.
  + Remove unnecessary `extra_fragment` argument to `variant_field()`;
    it was only used to do lookups on failure.
  + Remove various lookups related to associated items
  + Remove distinction between 'not in scope' and 'no associated item'

- Don't perform unnecessary copies
- Remove unused variables and code
- Update tests
- Note why looking at other namespaces is still necessary
- 'has no inner item' -> 'contains no item'

bless tests

Author: jyn514

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -2,7 +2,7 @@ error: unresolved link to `v2`
   --> $DIR/deny-intra-link-resolution-failure.rs:3:6
    |
 LL | /// [v2]
-   |      ^^ no item named `v2` in `deny_intra_link_resolution_failure`
+   |      ^^ the module `deny_intra_link_resolution_failure` contains no item named `v2`
    |
 note: the lint level is defined here
   --> $DIR/deny-intra-link-resolution-failure.rs:1:9

src/test/rustdoc-ui/deny-intra-link-resolution-failure.stderr

@@ -6,19 +6,23 @@
 
 /// [path::to::nonexistent::module]
 //~^ ERROR unresolved link
-//~| NOTE no item named `path` in `intra_link_errors`
+//~| NOTE `intra_link_errors` contains no item named `path`
 
 /// [path::to::nonexistent::macro!]
 //~^ ERROR unresolved link
-//~| NOTE no item named `path` in `intra_link_errors`
+//~| NOTE `intra_link_errors` contains no item named `path`
 
 /// [type@path::to::nonexistent::type]
 //~^ ERROR unresolved link
-//~| NOTE no item named `path` in `intra_link_errors`
+//~| NOTE `intra_link_errors` contains no item named `path`
 
 /// [std::io::not::here]
 //~^ ERROR unresolved link
-//~| NOTE the module `io` has no inner item
+//~| NOTE `io` contains no item named `not`
+
+/// [type@std::io::not::here]
+//~^ ERROR unresolved link
+//~| NOTE `io` contains no item named `not`
 
 /// [std::io::Error::x]
 //~^ ERROR unresolved link
@@ -32,6 +36,10 @@
 //~^ ERROR unresolved link
 //~| NOTE `f` is a function, not a module
 
+/// [f::A!]
+//~^ ERROR unresolved link
+//~| NOTE `f` is a function, not a module
+
 /// [S::A]
 //~^ ERROR unresolved link
 //~| NOTE struct `S` has no field or associated item

src/test/rustdoc-ui/intra-link-errors.rs

@@ -2,7 +2,7 @@ error: unresolved link to `path::to::nonexistent::module`
   --> $DIR/intra-link-errors.rs:7:6
    |
 LL | /// [path::to::nonexistent::module]
-   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `path` in `intra_link_errors`
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the module `intra_link_errors` contains no item named `path`
    |
 note: the lint level is defined here
   --> $DIR/intra-link-errors.rs:1:9
@@ -14,64 +14,79 @@ error: unresolved link to `path::to::nonexistent::macro`
   --> $DIR/intra-link-errors.rs:11:6
    |
 LL | /// [path::to::nonexistent::macro!]
-   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `path` in `intra_link_errors`
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the module `intra_link_errors` contains no item named `path`
 
 error: unresolved link to `path::to::nonexistent::type`
   --> $DIR/intra-link-errors.rs:15:6
    |
 LL | /// [type@path::to::nonexistent::type]
-   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `path` in `intra_link_errors`
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the module `intra_link_errors` contains no item named `path`
 
 error: unresolved link to `std::io::not::here`
   --> $DIR/intra-link-errors.rs:19:6
    |
 LL | /// [std::io::not::here]
-   |      ^^^^^^^^^^^^^^^^^^ the module `io` has no inner item named `not`
+   |      ^^^^^^^^^^^^^^^^^^ the module `io` contains no item named `not`
 
-error: unresolved link to `std::io::Error::x`
+error: unresolved link to `std::io::not::here`
   --> $DIR/intra-link-errors.rs:23:6
    |
+LL | /// [type@std::io::not::here]
+   |      ^^^^^^^^^^^^^^^^^^^^^^^ the module `io` contains no item named `not`
+
+error: unresolved link to `std::io::Error::x`
+  --> $DIR/intra-link-errors.rs:27:6
+   |
 LL | /// [std::io::Error::x]
    |      ^^^^^^^^^^^^^^^^^ the struct `Error` has no field or associated item named `x`
 
 error: unresolved link to `std::io::ErrorKind::x`
-  --> $DIR/intra-link-errors.rs:27:6
+  --> $DIR/intra-link-errors.rs:31:6
    |
 LL | /// [std::io::ErrorKind::x]
    |      ^^^^^^^^^^^^^^^^^^^^^ the enum `ErrorKind` has no variant or associated item named `x`
 
 error: unresolved link to `f::A`
-  --> $DIR/intra-link-errors.rs:31:6
+  --> $DIR/intra-link-errors.rs:35:6
    |
 LL | /// [f::A]
    |      ^^^^ `f` is a function, not a module or type, and cannot have associated items
 
+error: unresolved link to `f::A`
+  --> $DIR/intra-link-errors.rs:39:6
+   |
+LL | /// [f::A!]
+   |      ^^^^^ `f` is a function, not a module or type, and cannot have associated items
+
 error: unresolved link to `S::A`
-  --> $DIR/intra-link-errors.rs:35:6
+  --> $DIR/intra-link-errors.rs:43:6
    |
 LL | /// [S::A]
    |      ^^^^ the struct `S` has no field or associated item named `A`
 
 error: unresolved link to `S::fmt`
-  --> $DIR/intra-link-errors.rs:39:6
+  --> $DIR/intra-link-errors.rs:47:6
    |
 LL | /// [S::fmt]
    |      ^^^^^^ the struct `S` has no field or associated item named `fmt`
 
 error: unresolved link to `E::D`
-  --> $DIR/intra-link-errors.rs:43:6
+  --> $DIR/intra-link-errors.rs:51:6
    |
 LL | /// [E::D]
    |      ^^^^ the enum `E` has no variant or associated item named `D`
 
 error: unresolved link to `u8::not_found`
-  --> $DIR/intra-link-errors.rs:47:6
+  --> $DIR/intra-link-errors.rs:55:6
    |
 LL | /// [u8::not_found]
-   |      ^^^^^^^^^^^^^ the builtin type `u8` does not have an associated item named `not_found`
+   |      ^^^^^^^^^^^^^
+   |      |
+   |      the builtin type `u8` does not have an associated item named `not_found`
+   |      the builtin type `u8` has no builtin type named `not_found`
 
 error: unresolved link to `S`
-  --> $DIR/intra-link-errors.rs:51:6
+  --> $DIR/intra-link-errors.rs:59:6
    |
 LL | /// [S!]
    |      ^^
@@ -80,7 +95,7 @@ LL | /// [S!]
    |      help: to link to the struct, prefix with `struct@`: `struct@S`
 
 error: unresolved link to `T::g`
-  --> $DIR/intra-link-errors.rs:69:6
+  --> $DIR/intra-link-errors.rs:77:6
    |
 LL | /// [type@T::g]
    |      ^^^^^^^^^
@@ -89,13 +104,13 @@ LL | /// [type@T::g]
    |      help: to link to the associated function, add parentheses: `T::g()`
 
 error: unresolved link to `T::h`
-  --> $DIR/intra-link-errors.rs:74:6
+  --> $DIR/intra-link-errors.rs:82:6
    |
 LL | /// [T::h!]
    |      ^^^^^ the trait `T` has no macro named `h`
 
 error: unresolved link to `S::h`
-  --> $DIR/intra-link-errors.rs:61:6
+  --> $DIR/intra-link-errors.rs:69:6
    |
 LL | /// [type@S::h]
    |      ^^^^^^^^^
@@ -104,13 +119,13 @@ LL | /// [type@S::h]
    |      help: to link to the associated function, add parentheses: `S::h()`
 
 error: unresolved link to `m`
-  --> $DIR/intra-link-errors.rs:81:6
+  --> $DIR/intra-link-errors.rs:89:6
    |
 LL | /// [m()]
    |      ^^^
    |      |
    |      this link resolves to the macro `m`, which is not in the value namespace
    |      help: to link to the macro, add an exclamation mark: `m!`
 
-error: aborting due to 16 previous errors
+error: aborting due to 18 previous errors
 

src/test/rustdoc-ui/intra-link-errors.stderr

@@ -2,7 +2,7 @@ error: unresolved link to `i`
   --> $DIR/intra-link-span-ice-55723.rs:9:10
    |
 LL | /// （arr[i]）
-   |           ^ no item named `i` in `intra_link_span_ice_55723`
+   |           ^ the module `intra_link_span_ice_55723` contains no item named `i`
    |
 note: the lint level is defined here
   --> $DIR/intra-link-span-ice-55723.rs:1:9

src/test/rustdoc-ui/intra-link-span-ice-55723.stderr

@@ -2,7 +2,7 @@ warning: unresolved link to `error`
   --> $DIR/intra-links-warning-crlf.rs:7:6
    |
 LL | /// [error]
-   |      ^^^^^ no item named `error` in `intra_links_warning_crlf`
+   |      ^^^^^ the module `intra_links_warning_crlf` contains no item named `error`
    |
    = note: `#[warn(broken_intra_doc_links)]` on by default
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
@@ -11,23 +11,23 @@ warning: unresolved link to `error1`
   --> $DIR/intra-links-warning-crlf.rs:12:11
    |
 LL | /// docs [error1]
-   |           ^^^^^^ no item named `error1` in `intra_links_warning_crlf`
+   |           ^^^^^^ the module `intra_links_warning_crlf` contains no item named `error1`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error2`
   --> $DIR/intra-links-warning-crlf.rs:15:11
    |
 LL | /// docs [error2]
-   |           ^^^^^^ no item named `error2` in `intra_links_warning_crlf`
+   |           ^^^^^^ the module `intra_links_warning_crlf` contains no item named `error2`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
   --> $DIR/intra-links-warning-crlf.rs:23:20
    |
 LL |  * It also has an [error].
-   |                    ^^^^^ no item named `error` in `intra_links_warning_crlf`
+   |                    ^^^^^ the module `intra_links_warning_crlf` contains no item named `error`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 

src/test/rustdoc-ui/intra-links-warning-crlf.stderr

@@ -10,53 +10,53 @@ warning: unresolved link to `Bar::foo`
   --> $DIR/intra-links-warning.rs:3:35
    |
 LL |        //! Test with [Foo::baz], [Bar::foo], ...
-   |                                   ^^^^^^^^ no item named `Bar` in `intra_links_warning`
+   |                                   ^^^^^^^^ the module `intra_links_warning` contains no item named `Bar`
 
 warning: unresolved link to `Uniooon::X`
   --> $DIR/intra-links-warning.rs:6:13
    |
 LL |      //! , [Uniooon::X] and [Qux::Z].
-   |             ^^^^^^^^^^ no item named `Uniooon` in `intra_links_warning`
+   |             ^^^^^^^^^^ the module `intra_links_warning` contains no item named `Uniooon`
 
 warning: unresolved link to `Qux::Z`
   --> $DIR/intra-links-warning.rs:6:30
    |
 LL |      //! , [Uniooon::X] and [Qux::Z].
-   |                              ^^^^^^ no item named `Qux` in `intra_links_warning`
+   |                              ^^^^^^ the module `intra_links_warning` contains no item named `Qux`
 
 warning: unresolved link to `Uniooon::X`
   --> $DIR/intra-links-warning.rs:10:14
    |
 LL |       //! , [Uniooon::X] and [Qux::Z].
-   |              ^^^^^^^^^^ no item named `Uniooon` in `intra_links_warning`
+   |              ^^^^^^^^^^ the module `intra_links_warning` contains no item named `Uniooon`
 
 warning: unresolved link to `Qux::Z`
   --> $DIR/intra-links-warning.rs:10:31
    |
 LL |       //! , [Uniooon::X] and [Qux::Z].
-   |                               ^^^^^^ no item named `Qux` in `intra_links_warning`
+   |                               ^^^^^^ the module `intra_links_warning` contains no item named `Qux`
 
 warning: unresolved link to `Qux:Y`
   --> $DIR/intra-links-warning.rs:14:13
    |
 LL |        /// [Qux:Y]
-   |             ^^^^^ no item named `Qux:Y` in `intra_links_warning`
+   |             ^^^^^ the module `intra_links_warning` contains no item named `Qux:Y`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
   --> $DIR/intra-links-warning.rs:58:30
    |
 LL |  * time to introduce a link [error]*/
-   |                              ^^^^^ no item named `error` in `intra_links_warning`
+   |                              ^^^^^ the module `intra_links_warning` contains no item named `error`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
   --> $DIR/intra-links-warning.rs:64:30
    |
 LL |  * time to introduce a link [error]
-   |                              ^^^^^ no item named `error` in `intra_links_warning`
+   |                              ^^^^^ the module `intra_links_warning` contains no item named `error`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
@@ -70,7 +70,7 @@ LL | #[doc = "single line [error]"]
 
            single line [error]
                         ^^^^^
-   = note: no item named `error` in `intra_links_warning`
+   = note: the module `intra_links_warning` contains no item named `error`
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
@@ -83,7 +83,7 @@ LL | #[doc = "single line with \"escaping\" [error]"]
 
            single line with "escaping" [error]
                                         ^^^^^
-   = note: no item named `error` in `intra_links_warning`
+   = note: the module `intra_links_warning` contains no item named `error`
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
@@ -98,46 +98,46 @@ LL | | /// [error]
 
            [error]
             ^^^^^
-   = note: no item named `error` in `intra_links_warning`
+   = note: the module `intra_links_warning` contains no item named `error`
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error1`
   --> $DIR/intra-links-warning.rs:80:11
    |
 LL | /// docs [error1]
-   |           ^^^^^^ no item named `error1` in `intra_links_warning`
+   |           ^^^^^^ the module `intra_links_warning` contains no item named `error1`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error2`
   --> $DIR/intra-links-warning.rs:82:11
    |
 LL | /// docs [error2]
-   |           ^^^^^^ no item named `error2` in `intra_links_warning`
+   |           ^^^^^^ the module `intra_links_warning` contains no item named `error2`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `BarA`
   --> $DIR/intra-links-warning.rs:21:10
    |
 LL | /// bar [BarA] bar
-   |          ^^^^ no item named `BarA` in `intra_links_warning`
+   |          ^^^^ the module `intra_links_warning` contains no item named `BarA`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `BarB`
   --> $DIR/intra-links-warning.rs:27:9
    |
 LL |  * bar [BarB] bar
-   |         ^^^^ no item named `BarB` in `intra_links_warning`
+   |         ^^^^ the module `intra_links_warning` contains no item named `BarB`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `BarC`
   --> $DIR/intra-links-warning.rs:34:6
    |
 LL | bar [BarC] bar
-   |      ^^^^ no item named `BarC` in `intra_links_warning`
+   |      ^^^^ the module `intra_links_warning` contains no item named `BarC`
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
@@ -151,7 +151,7 @@ LL | #[doc = "Foo\nbar [BarD] bar\nbaz"]
 
            bar [BarD] bar
                 ^^^^
-   = note: no item named `BarD` in `intra_links_warning`
+   = note: the module `intra_links_warning` contains no item named `BarD`
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `BarF`
@@ -167,7 +167,7 @@ LL | f!("Foo\nbar [BarF] bar\nbaz");
 
            bar [BarF] bar
                 ^^^^
-   = note: no item named `BarF` in `intra_links_warning`
+   = note: the module `intra_links_warning` contains no item named `BarF`
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
    = note: this warning originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 

src/test/rustdoc-ui/intra-links-warning.stderr

@@ -32,7 +32,7 @@ error: unresolved link to `error`
   --> $DIR/lint-group.rs:9:29
    |
 LL | /// what up, let's make an [error]
-   |                             ^^^^^ no item named `error` in `lint_group`
+   |                             ^^^^^ the module `lint_group` contains no item named `error`
    |
 note: the lint level is defined here
   --> $DIR/lint-group.rs:7:9