Rollup merge of #83216 - jyn514:register-tool, r=petrochenkov

Allow registering tool lints with `register_tool`

Previously, there was no way to add a custom tool prefix, even if the tool
itself had registered a lint:

 ```rust
 #![feature(register_tool)]
 #![register_tool(xyz)]
 #![warn(xyz::my_lint)]
 ```

```
$ rustc unknown-lint.rs  --crate-type lib
error[E0710]: an unknown tool name found in scoped lint: `xyz::my_lint`
 --> unknown-lint.rs:3:9
  |
3 | #![warn(xyz::my_lint)]
  |         ^^^
```

This allows opting-in to lints from other tools using `register_tool`.

cc https://github.com/rust-lang/rust/issues/66079#issuecomment-788589193, ``@chorman0773``
r? ``@petrochenkov``

src/test/ui/lint/register-tool-lint.rs

@@ -0,0 +1,11 @@
+#![crate_type = "lib"]
+#![feature(register_tool)]
+#![register_tool(xyz)]
+#![warn(xyz::my_lint)] // this should not error
+#![warn(abc::my_lint)]
+//~^ ERROR unknown tool name `abc` found in scoped lint
+//~| HELP add `#![register_tool(abc)]`
+//~| ERROR unknown tool name `abc`
+//~| HELP add `#![register_tool(abc)]`
+//~| ERROR unknown tool name `abc`
+//~| HELP add `#![register_tool(abc)]`

src/test/ui/lint/register-tool-lint.stderr

@@ -0,0 +1,27 @@
+error[E0710]: unknown tool name `abc` found in scoped lint: `abc::my_lint`
+  --> $DIR/register-tool-lint.rs:5:9
+   |
+LL | #![warn(abc::my_lint)]
+   |         ^^^
+   |
+   = help: add `#![register_tool(abc)]` to the crate root
+
+error[E0710]: unknown tool name `abc` found in scoped lint: `abc::my_lint`
+  --> $DIR/register-tool-lint.rs:5:9
+   |
+LL | #![warn(abc::my_lint)]
+   |         ^^^
+   |
+   = help: add `#![register_tool(abc)]` to the crate root
+
+error[E0710]: unknown tool name `abc` found in scoped lint: `abc::my_lint`
+  --> $DIR/register-tool-lint.rs:5:9
+   |
+LL | #![warn(abc::my_lint)]
+   |         ^^^
+   |
+   = help: add `#![register_tool(abc)]` to the crate root
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0710`.

src/test/ui/tool_lints.rs

@@ -1,5 +1,5 @@
 #[warn(foo::bar)]
-//~^ ERROR an unknown tool name found in scoped lint: `foo::bar`
-//~| ERROR an unknown tool name found in scoped lint: `foo::bar`
-//~| ERROR an unknown tool name found in scoped lint: `foo::bar`
+//~^ ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
+//~| ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
+//~| ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
 fn main() {}

src/test/ui/tool_lints.stderr

@@ -1,20 +1,26 @@
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/tool_lints.rs:1:8
    |
 LL | #[warn(foo::bar)]
    |        ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/tool_lints.rs:1:8
    |
 LL | #[warn(foo::bar)]
    |        ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/tool_lints.rs:1:8
    |
 LL | #[warn(foo::bar)]
    |        ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
 error: aborting due to 3 previous errors
 

src/test/ui/unknown-lint-tool-name.rs

@@ -1,8 +1,8 @@
-#![deny(foo::bar)] //~ ERROR an unknown tool name found in scoped lint: `foo::bar`
-                   //~| ERROR an unknown tool name found in scoped lint: `foo::bar`
-                   //~| ERROR an unknown tool name found in scoped lint: `foo::bar`
+#![deny(foo::bar)] //~ ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
+                   //~| ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
+                   //~| ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
 
-#[allow(foo::bar)] //~ ERROR an unknown tool name found in scoped lint: `foo::bar`
-                   //~| ERROR an unknown tool name found in scoped lint: `foo::bar`
-                   //~| ERROR an unknown tool name found in scoped lint: `foo::bar`
+#[allow(foo::bar)] //~ ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
+                   //~| ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
+                   //~| ERROR unknown tool name `foo` found in scoped lint: `foo::bar`
 fn main() {}

src/test/ui/unknown-lint-tool-name.stderr

@@ -1,38 +1,50 @@
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/unknown-lint-tool-name.rs:1:9
    |
 LL | #![deny(foo::bar)]
    |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/unknown-lint-tool-name.rs:5:9
    |
 LL | #[allow(foo::bar)]
    |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/unknown-lint-tool-name.rs:1:9
    |
 LL | #![deny(foo::bar)]
    |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/unknown-lint-tool-name.rs:5:9
    |
 LL | #[allow(foo::bar)]
    |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/unknown-lint-tool-name.rs:1:9
    |
 LL | #![deny(foo::bar)]
    |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
-error[E0710]: an unknown tool name found in scoped lint: `foo::bar`
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::bar`
   --> $DIR/unknown-lint-tool-name.rs:5:9
    |
 LL | #[allow(foo::bar)]
    |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
 
 error: aborting due to 6 previous errors