[WIP] give better errors for broken intra doc links

Author: jyn514

compiler/rustc_hir/src/def.rs

@@ -6,6 +6,7 @@ use rustc_ast::NodeId;
 use rustc_macros::HashStable_Generic;
 use rustc_span::hygiene::MacroKind;
 
+use std::array::IntoIter;
 use std::fmt::Debug;
 
 /// Encodes if a `DefKind::Ctor` is the constructor of an enum variant or a struct.
@@ -291,6 +292,14 @@ impl<T> PerNS<T> {
     pub fn map<U, F: FnMut(T) -> U>(self, mut f: F) -> PerNS<U> {
         PerNS { value_ns: f(self.value_ns), type_ns: f(self.type_ns), macro_ns: f(self.macro_ns) }
     }
+
+    pub fn into_iter(self) -> IntoIter<T, 3> {
+        IntoIter::new([self.value_ns, self.type_ns, self.macro_ns])
+    }
+
+    pub fn iter(&self) -> IntoIter<&T, 3> {
+        IntoIter::new([&self.value_ns, &self.type_ns, &self.macro_ns])
+    }
 }
 
 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {

compiler/rustc_hir/src/lib.rs

@@ -2,6 +2,7 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
 
+#![feature(array_value_iter)]
 #![feature(crate_visibility_modifier)]
 #![feature(const_fn)] // For the unsizing cast on `&[]`
 #![feature(const_panic)]

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -2,13 +2,14 @@ error: unresolved link to `v2`
   --> $DIR/deny-intra-link-resolution-failure.rs:3:6
    |
 LL | /// [v2]
-   |      ^^ unresolved link
+   |      ^^
    |
 note: the lint level is defined here
   --> $DIR/deny-intra-link-resolution-failure.rs:1:9
    |
 LL | #![deny(broken_intra_doc_links)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
+   = note: no item named `v2` is in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 error: aborting due to previous error

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

@@ -2,14 +2,15 @@ error: unresolved link to `TypeAlias::hoge`
   --> $DIR/intra-doc-alias-ice.rs:5:30
    |
 LL | /// [broken cross-reference](TypeAlias::hoge)
-   |                              ^^^^^^^^^^^^^^^ unresolved link
+   |                              ^^^^^^^^^^^^^^^
    |
 note: the lint level is defined here
   --> $DIR/intra-doc-alias-ice.rs:1:9
    |
 LL | #![deny(broken_intra_doc_links)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
-   = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
+   = note: this link partially resolves to the type alias `TypeAlias`,
+   = note: `TypeAlias` has no field, variant, or associated item named `hoge`
 
 error: aborting due to previous error
 

src/test/rustdoc-ui/intra-doc-alias-ice.stderr

@@ -0,0 +1,59 @@
+#![deny(broken_intra_doc_links)]
+//~^ NOTE lint level is defined
+
+//! [std::io::oops]
+//! [std::io::oops::not::here]
+
+// FIXME: this should say that it was skipped (maybe an allowed by default lint?)
+/// [<invalid syntax>]
+
+// FIXME: this could say which path was the first to not be found (in this case, `path`)
+/// [path::to::nonexistent::module]
+//~^ ERROR unresolved link
+//~| NOTE no item named `path::to::nonexistent` is in scope
+//~| HELP to escape
+
+// TODO: why does this say `f` and not `f::A`??
+/// [f::A]
+//~^ ERROR unresolved link
+//~| NOTE no item named `f` is in scope
+//~| HELP to escape
+
+/// [S::A]
+//~^ ERROR unresolved link
+//~| NOTE this link partially resolves
+//~| NOTE `S` has no field
+
+/// [S::fmt]
+//~^ ERROR unresolved link
+//~| NOTE this link partially resolves
+//~| NOTE `S` has no field
+
+/// [E::D]
+//~^ ERROR unresolved link
+//~| NOTE this link partially resolves
+//~| NOTE `E` has no field
+
+/// [u8::not_found]
+//~^ ERROR unresolved link
+//~| NOTE the builtin type `u8` does not have an associated item named `not_found`
+
+/// [S!]
+//~^ ERROR unresolved link
+//~| HELP to link to the unit struct, use its disambiguator
+//~| NOTE this link resolves to the unit struct `S`
+pub fn f() {}
+#[derive(Debug)]
+pub struct S;
+
+pub enum E { A, B, C }
+
+/// [type@S::h]
+impl S {
+    pub fn h() {}
+}
+
+/// [type@T::g]
+pub trait T {
+    fn g() {}
+}

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

@@ -0,0 +1,68 @@
+error: unresolved link to `path::to::nonexistent::module`
+  --> $DIR/intra-link-errors.rs:8:6
+   |
+LL | /// [path::to::nonexistent::module]
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/intra-link-errors.rs:1:9
+   |
+LL | #![deny(broken_intra_doc_links)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+   = note: no item named `path::to::nonexistent` is in scope
+   = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
+
+error: unresolved link to `f::A`
+  --> $DIR/intra-link-errors.rs:14:6
+   |
+LL | /// [f::A]
+   |      ^^^^
+   |
+   = note: no item named `f` is in scope
+   = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
+
+error: unresolved link to `S::A`
+  --> $DIR/intra-link-errors.rs:19:6
+   |
+LL | /// [S::A]
+   |      ^^^^
+   |
+   = note: this link partially resolves to the struct `S`,
+   = note: `S` has no field, variant, or associated item named `A`
+
+error: unresolved link to `S::fmt`
+  --> $DIR/intra-link-errors.rs:24:6
+   |
+LL | /// [S::fmt]
+   |      ^^^^^^
+   |
+   = note: this link partially resolves to the struct `S`,
+   = note: `S` has no field, variant, or associated item named `fmt`
+
+error: unresolved link to `E::D`
+  --> $DIR/intra-link-errors.rs:29:6
+   |
+LL | /// [E::D]
+   |      ^^^^
+   |
+   = note: this link partially resolves to the enum `E`,
+   = note: `E` has no field, variant, or associated item named `D`
+
+error: unresolved link to `u8::not_found`
+  --> $DIR/intra-link-errors.rs:34:6
+   |
+LL | /// [u8::not_found]
+   |      ^^^^^^^^^^^^^
+   |
+   = note: the builtin type `u8` does not have an associated item named `not_found`
+
+error: unresolved link to `S`
+  --> $DIR/intra-link-errors.rs:38:6
+   |
+LL | /// [S!]
+   |      ^^ help: to link to the unit struct, use its disambiguator: `value@S`
+   |
+   = note: this link resolves to the unit struct `S`, which is not in the value namespace
+
+error: aborting due to 7 previous errors
+

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

@@ -2,13 +2,14 @@ error: unresolved link to `i`
   --> $DIR/intra-link-span-ice-55723.rs:9:10
    |
 LL | /// （arr[i]）
-   |           ^ unresolved link
+   |           ^
    |
 note: the lint level is defined here
   --> $DIR/intra-link-span-ice-55723.rs:1:9
    |
 LL | #![deny(broken_intra_doc_links)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
+   = note: no item named `i` is in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 error: aborting due to previous error

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

@@ -2,33 +2,37 @@ warning: unresolved link to `error`
   --> $DIR/intra-links-warning-crlf.rs:7:6
    |
 LL | /// [error]
-   |      ^^^^^ unresolved link
+   |      ^^^^^
    |
    = note: `#[warn(broken_intra_doc_links)]` on by default
+   = note: no item named `error` is in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error1`
   --> $DIR/intra-links-warning-crlf.rs:12:11
    |
 LL | /// docs [error1]
-   |           ^^^^^^ unresolved link
+   |           ^^^^^^
    |
+   = note: no item named `error1` is in scope
    = 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]
-   |           ^^^^^^ unresolved link
+   |           ^^^^^^
    |
+   = note: no item named `error2` is in scope
    = 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].
-   |                    ^^^^^ unresolved link
+   |                    ^^^^^
    |
+   = note: no item named `error` is in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: 4 warnings emitted