Remove `rustc::existing_doc_keyword` lint.

`CheckAttrVisitor::check_doc_keyword` checks `#[doc(keyword = "..")]`
attributes to ensure they are on an empty module, and that the value is
a non-empty identifier.

The `rustc::existing_doc_keyword` lint checks these attributes to ensure
that the value is the name of a keyword.

It's silly to have two different checking mechanisms for these
attributes. This commit does the following.
- Changes `check_doc_keyword` to check that the value is the name of a
  keyword (avoiding the need for the identifier check, which removes a
  dependency on `rustc_lexer`).
- Removes the lint.
- Updates tests accordingly.

There is one hack: the `SelfTy` FIXME case used to used to be handled by
disabling the lint, but now is handled with a special case in
`is_doc_keyword`. That hack will go away if/when the FIXME is fixed.

Co-Authored-By: Guillaume Gomez <guillaume1.gomez@gmail.com>

12 files changed, 32 insertions, 43 deletions

diff --git a/tests/rustdoc-gui/search-result-color.goml b/tests/rustdoc-gui/search-result-color.goml
index e8da43eb896..e6dd504d703 100644
--- a/tests/rustdoc-gui/search-result-color.goml
+++ b/tests/rustdoc-gui/search-result-color.goml
@@ -140,7 +140,8 @@ define-function: (
     },
 )
 
-go-to: "file://" + |DOC_PATH| + "/test_docs/index.html?search=coo"
+// Searching for the `for` keyword
+go-to: "file://" + |DOC_PATH| + "/test_docs/index.html?search=fo"
 
 // This is needed so that the text color is computed.
 show-text: true
diff --git a/tests/rustdoc-gui/search-result-keyword.goml b/tests/rustdoc-gui/search-result-keyword.goml
index 370edce2ddd..02305f2587c 100644
--- a/tests/rustdoc-gui/search-result-keyword.goml
+++ b/tests/rustdoc-gui/search-result-keyword.goml
@@ -1,8 +1,8 @@
 // Checks that the "keyword" results have the expected text alongside them.
 go-to: "file://" + |DOC_PATH| + "/test_docs/index.html"
-write-into: (".search-input", "CookieMonster")
+write-into: (".search-input", "for")
 // To be SURE that the search will be run.
 press-key: 'Enter'
 // Waiting for the search results to appear...
 wait-for: "#search-tabs"
-assert-text: (".result-keyword .result-name", "keyword CookieMonster")
+assert-text: (".result-keyword .result-name", "keyword for")
diff --git a/tests/rustdoc-gui/search-tab.goml b/tests/rustdoc-gui/search-tab.goml
index 4329726398c..3879c127fd0 100644
--- a/tests/rustdoc-gui/search-tab.goml
+++ b/tests/rustdoc-gui/search-tab.goml
@@ -78,7 +78,7 @@ call-function: ("check-colors", {
 set-window-size: (851, 600)
 
 // Check the size and count in tabs
-assert-text: ("#search-tabs > button:nth-child(1) > .count", " (25) ")
+assert-text: ("#search-tabs > button:nth-child(1) > .count", " (26) ")
 assert-text: ("#search-tabs > button:nth-child(2) > .count", " (6)  ")
 assert-text: ("#search-tabs > button:nth-child(3) > .count", " (0)  ")
 store-property: ("#search-tabs > button:nth-child(1)", {"offsetWidth": buttonWidth})
diff --git a/tests/rustdoc-gui/src/test_docs/lib.rs b/tests/rustdoc-gui/src/test_docs/lib.rs
index 91aa2c3fae5..dae13d9ac18 100644
--- a/tests/rustdoc-gui/src/test_docs/lib.rs
+++ b/tests/rustdoc-gui/src/test_docs/lib.rs
@@ -156,7 +156,7 @@ pub enum AnEnum {
     WithVariants { and: usize, sub: usize, variants: usize },
 }
 
-#[doc(keyword = "CookieMonster")]
+#[doc(keyword = "for")]
 /// Some keyword.
 pub mod keyword {}
 
diff --git a/tests/rustdoc-json/keyword.rs b/tests/rustdoc-json/keyword.rs
index 7a820cd1487..8a2130f1978 100644
--- a/tests/rustdoc-json/keyword.rs
+++ b/tests/rustdoc-json/keyword.rs
@@ -13,8 +13,8 @@
 /// this is a test!
 pub mod foo {}
 
-//@ !has "$.index[*][?(@.name=='hello')]"
+//@ !has "$.index[*][?(@.name=='break')]"
 //@ !has "$.index[*][?(@.name=='bar')]"
-#[doc(keyword = "hello")]
+#[doc(keyword = "break")]
 /// hello
 mod bar {}
diff --git a/tests/rustdoc-json/keyword_private.rs b/tests/rustdoc-json/keyword_private.rs
index 7a030041f7c..2a13bf10d5d 100644
--- a/tests/rustdoc-json/keyword_private.rs
+++ b/tests/rustdoc-json/keyword_private.rs
@@ -11,10 +11,10 @@
 /// this is a test!
 pub mod foo {}
 
-//@ !has "$.index[*][?(@.name=='hello')]"
+//@ !has "$.index[*][?(@.name=='break')]"
 //@ has "$.index[*][?(@.name=='bar')]"
-//@ is   "$.index[*][?(@.name=='bar')].attrs" '["#[doc(keyword = \"hello\")]"]'
+//@ is   "$.index[*][?(@.name=='bar')].attrs" '["#[doc(keyword = \"break\")]"]'
 //@ is   "$.index[*][?(@.name=='bar')].docs" '"hello"'
-#[doc(keyword = "hello")]
+#[doc(keyword = "break")]
 /// hello
 mod bar {}
diff --git a/tests/rustdoc-ui/invalid-keyword.stderr b/tests/rustdoc-ui/invalid-keyword.stderr
index 82faaaab47f..c1e41d3b0b3 100644
--- a/tests/rustdoc-ui/invalid-keyword.stderr
+++ b/tests/rustdoc-ui/invalid-keyword.stderr
@@ -1,8 +1,10 @@
-error: `foo df` is not a valid identifier
+error: nonexistent keyword `foo df` used in `#[doc(keyword = "...")]`
   --> $DIR/invalid-keyword.rs:3:17
    |
 LL | #[doc(keyword = "foo df")]
    |                 ^^^^^^^^
+   |
+   = help: only existing keywords are allowed in core/std
 
 error: aborting due to 1 previous error
 
diff --git a/tests/rustdoc/keyword.rs b/tests/rustdoc/keyword.rs
index 519e1944bc7..8f86c8ffd38 100644
--- a/tests/rustdoc/keyword.rs
+++ b/tests/rustdoc/keyword.rs
@@ -16,7 +16,7 @@
 /// this is a test!
 mod foo{}
 
-//@ has foo/keyword.foo.html '//section[@id="main-content"]//div[@class="docblock"]//p' 'hello'
-#[doc(keyword = "foo")]
+//@ has foo/keyword.break.html '//section[@id="main-content"]//div[@class="docblock"]//p' 'hello'
+#[doc(keyword = "break")]
 /// hello
 mod bar {}
diff --git a/tests/ui/internal-lints/existing_doc_keyword.rs b/tests/ui/internal-lints/existing_doc_keyword.rs
deleted file mode 100644
index 8f60b931591..00000000000
--- a/tests/ui/internal-lints/existing_doc_keyword.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-//@ compile-flags: -Z unstable-options
-
-#![feature(rustdoc_internals)]
-
-#![crate_type = "lib"]
-
-#![deny(rustc::existing_doc_keyword)]
-
-#[doc(keyword = "tadam")] //~ ERROR
-mod tadam {}
diff --git a/tests/ui/internal-lints/existing_doc_keyword.stderr b/tests/ui/internal-lints/existing_doc_keyword.stderr
deleted file mode 100644
index 5573e7ce4d0..00000000000
--- a/tests/ui/internal-lints/existing_doc_keyword.stderr
+++ /dev/null
@@ -1,15 +0,0 @@
-error: found non-existing keyword `tadam` used in `#[doc(keyword = "...")]`
-  --> $DIR/existing_doc_keyword.rs:9:1
-   |
-LL | #[doc(keyword = "tadam")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: only existing keywords are allowed in core/std
-note: the lint level is defined here
-  --> $DIR/existing_doc_keyword.rs:7:9
-   |
-LL | #![deny(rustc::existing_doc_keyword)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 1 previous error
-
diff --git a/tests/ui/rustdoc/doc_keyword.rs b/tests/ui/rustdoc/doc_keyword.rs
index 68a8802b2f6..e0995f336da 100644
--- a/tests/ui/rustdoc/doc_keyword.rs
+++ b/tests/ui/rustdoc/doc_keyword.rs
@@ -1,14 +1,14 @@
 #![crate_type = "lib"]
 #![feature(rustdoc_internals)]
 
-#![doc(keyword = "hello")] //~ ERROR
-
-#[doc(keyword = "hell")] //~ ERROR
+#![doc(keyword = "hello")]
+//~^ ERROR `#![doc(keyword = "...")]` isn't allowed as a crate-level attribute
+#[doc(keyword = "hell")] //~ ERROR `#[doc(keyword = "...")]` should be used on empty modules
 mod foo {
     fn hell() {}
 }
 
-#[doc(keyword = "hall")] //~ ERROR
+#[doc(keyword = "hall")] //~ ERROR `#[doc(keyword = "...")]` should be used on modules
 fn foo() {}
 
 
@@ -18,3 +18,6 @@ trait Foo {
     //~^ ERROR: `#[doc(keyword = "...")]` should be used on modules
     fn quux() {}
 }
+
+#[doc(keyword = "tadam")] //~ ERROR nonexistent keyword `tadam`
+mod tadam {}
diff --git a/tests/ui/rustdoc/doc_keyword.stderr b/tests/ui/rustdoc/doc_keyword.stderr
index a1d0e4ffc09..584daae2f1a 100644
--- a/tests/ui/rustdoc/doc_keyword.stderr
+++ b/tests/ui/rustdoc/doc_keyword.stderr
@@ -10,6 +10,14 @@ error: `#[doc(keyword = "...")]` should be used on modules
 LL | #[doc(keyword = "hall")]
    |       ^^^^^^^^^^^^^^^^
 
+error: nonexistent keyword `tadam` used in `#[doc(keyword = "...")]`
+  --> $DIR/doc_keyword.rs:22:17
+   |
+LL | #[doc(keyword = "tadam")]
+   |                 ^^^^^^^
+   |
+   = help: only existing keywords are allowed in core/std
+
 error: `#[doc(keyword = "...")]` should be used on modules
   --> $DIR/doc_keyword.rs:17:11
    |
@@ -22,5 +30,5 @@ error: `#![doc(keyword = "...")]` isn't allowed as a crate-level attribute
 LL | #![doc(keyword = "hello")]
    |        ^^^^^^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors