Expand checks for register_tool

compiler/rustc_attr_parsing/src/attributes/crate_level.rs

@@ -1,12 +1,14 @@
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_feature::AttributeStability;
 use rustc_hir::attrs::{CrateType, WindowsSubsystemKind};
-use rustc_session::lint::builtin::UNKNOWN_CRATE_TYPES;
+use rustc_session::lint::builtin::{DUPLICATE_TOOLS, UNKNOWN_CRATE_TYPES};
 use rustc_span::Symbol;
 use rustc_span::edit_distance::find_best_match_for_name_with_substrings;
 
 use super::prelude::*;
-use crate::diagnostics::{ToolReserved, UnknownCrateTypes, UnknownCrateTypesSuggestion};
+use crate::diagnostics::{
+    DuplicateTool, ToolReserved, UnknownCrateTypes, UnknownCrateTypesSuggestion,
+};
 
 pub(crate) struct CrateNameParser;
 
@@ -352,15 +354,29 @@ fn parse_register_tool(
             cx.adcx().expected_identifier(path.span());
             continue;
         };
+        if !ident.name.can_be_raw() {
+            cx.adcx().expected_identifier(path.span());
+            continue;
+        }
 
         if ident.name == sym::rustc {
             cx.should_emit
                 .emit_err(cx.dcx().create_err(ToolReserved { span: ident.span, tool: ident }));
             continue;
         }
 
+        let mut lint_emitted = false;
         for tools in tools.iter_mut() {
-            tools.insert(ident);
+            if let Some(old_ident) = tools.replace(ident)
+                && !lint_emitted
+            {
+                lint_emitted = true;
+                cx.emit_lint(
+                    DUPLICATE_TOOLS,
+                    DuplicateTool { span: ident.span, tool: ident, old_ident_span: old_ident.span },
+                    ident.span,
+                );
+            }
         }
     }
 }

compiler/rustc_attr_parsing/src/diagnostics.rs

@@ -829,6 +829,16 @@ pub(crate) struct UnknownExternLangItem {
     pub lang_item: Symbol,
 }
 
+#[derive(Diagnostic)]
+#[diag("duplicate tool `{$tool}` registered")]
+pub(crate) struct DuplicateTool {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) tool: Ident,
+    #[label("already registered here")]
+    pub(crate) old_ident_span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag("tool `{$tool}` is reserved and cannot be registered")]
 pub(crate) struct ToolReserved {

compiler/rustc_lint_defs/src/builtin.rs

@@ -44,6 +44,7 @@ pub mod hardwired {
             DEPRECATED_WHERE_CLAUSE_LOCATION,
             DUPLICATE_FEATURES,
             DUPLICATE_MACRO_ATTRIBUTES,
+            DUPLICATE_TOOLS,
             ELIDED_LIFETIMES_IN_PATHS,
             EXPLICIT_BUILTIN_CFGS_IN_FLAGS,
             EXPORTED_PRIVATE_DEPENDENCIES,
@@ -5712,3 +5713,29 @@ declare_lint! {
         report_in_deps: false,
     };
 }
+
+declare_lint! {
+    /// The `duplicate_tools` lint detects duplicate tools found in crate-level
+    /// [`register_tool` attributes] (including `register_attribute_tool` or `register_lint_tool`).
+    ///
+    /// [`register_tool` attributes]: https://doc.rust-lang.org/nightly/unstable-book/language-features/register-tool.html
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![feature(register_tool)]
+    /// #![register_tool(foo)]
+    /// #![register_tool(foo)]
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Enabling a tool more than once is a no-op.
+    /// To avoid this warning, remove the second `register_tool()` attribute.
+    pub DUPLICATE_TOOLS,
+    Deny,
+    "duplicate tools found in crate-level `#[register_tools]` directives",
+    @feature_gate = register_tool;
+}

tests/ui/feature-gates/feature-gate-register_tool.rs

@@ -1,3 +1,4 @@
+#![allow(duplicate_tools)] //~ WARN [unknown_lints]
 #![register_tool(tool)] //~ ERROR the `register_tool` attribute is an experimental feature
 #![register_attribute_tool(attr_tool)] //~ ERROR the `register_attribute_tool` attribute is an experimental feature
 #![register_lint_tool(lint_tool)] //~ ERROR the `register_lint_tool` attribute is an experimental feature

tests/ui/feature-gates/feature-gate-register_tool.stderr

@@ -1,5 +1,17 @@
+warning: unknown lint: `duplicate_tools`
+  --> $DIR/feature-gate-register_tool.rs:1:10
+   |
+LL | #![allow(duplicate_tools)]
+   |          ^^^^^^^^^^^^^^^
+   |
+   = note: the `duplicate_tools` lint is unstable
+   = note: see issue #66079 <https://github.com/rust-lang/rust/issues/66079> for more information
+   = help: add `#![feature(register_tool)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: `#[warn(unknown_lints)]` on by default
+
 error[E0658]: the `register_tool` attribute is an experimental feature
-  --> $DIR/feature-gate-register_tool.rs:1:4
+  --> $DIR/feature-gate-register_tool.rs:2:4
    |
 LL | #![register_tool(tool)]
    |    ^^^^^^^^^^^^^
@@ -9,7 +21,7 @@ LL | #![register_tool(tool)]
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: the `register_attribute_tool` attribute is an experimental feature
-  --> $DIR/feature-gate-register_tool.rs:2:4
+  --> $DIR/feature-gate-register_tool.rs:3:4
    |
 LL | #![register_attribute_tool(attr_tool)]
    |    ^^^^^^^^^^^^^^^^^^^^^^^
@@ -19,7 +31,7 @@ LL | #![register_attribute_tool(attr_tool)]
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: the `register_lint_tool` attribute is an experimental feature
-  --> $DIR/feature-gate-register_tool.rs:3:4
+  --> $DIR/feature-gate-register_tool.rs:4:4
    |
 LL | #![register_lint_tool(lint_tool)]
    |    ^^^^^^^^^^^^^^^^^^
@@ -28,6 +40,6 @@ LL | #![register_lint_tool(lint_tool)]
    = help: add `#![feature(register_tool)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 3 previous errors
+error: aborting due to 3 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.

tests/ui/tool-attributes/auxiliary/use_tool.rs

@@ -0,0 +1,2 @@
+#![feature(register_tool)]
+#![register_tool(foo)]

tests/ui/tool-attributes/crate-attr-dup-tool.rs

@@ -0,0 +1,13 @@
+//@ check-pass
+//@ compile-flags: -Z crate-attr=feature(register_tool) -Z crate-attr=register_tool(foo)
+//@ compile-flags: -Z crate-attr=register_attribute_tool(bar) -Z crate-attr=register_lint_tool(baz)
+//@ compile-flags: -A duplicate_features -A duplicate_tools
+#![feature(register_tool)]
+#![register_tool(foo)]
+#![register_attribute_tool(bar)]
+#![register_lint_tool(baz)]
+
+#[foo::foo]
+#[bar::bar]
+#[allow(foo::baz, baz::baz)]
+fn main() {}

tests/ui/tool-attributes/cross-crate.rs

@@ -0,0 +1,10 @@
+//@ aux-build: use_tool.rs
+
+// `use_tool` references tool "foo", and we want to check that it has no impact on this crate.
+extern crate use_tool;
+
+#[foo::bar] //~ ERROR cannot find module or crate `foo` in this scope
+#[allow(foo::baz)] //~ ERROR unknown tool name `foo`
+                   //~| ERROR unknown tool name `foo`
+                   //~| ERROR unknown tool name `foo`
+fn main() {}

tests/ui/tool-attributes/cross-crate.stderr

@@ -0,0 +1,36 @@
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::baz`
+  --> $DIR/cross-crate.rs:7:9
+   |
+LL | #[allow(foo::baz)]
+   |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
+
+error[E0433]: cannot find module or crate `foo` in this scope
+  --> $DIR/cross-crate.rs:6:3
+   |
+LL | #[foo::bar]
+   |   ^^^ use of unresolved module or unlinked crate `foo`
+
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::baz`
+  --> $DIR/cross-crate.rs:7:9
+   |
+LL | #[allow(foo::baz)]
+   |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0710]: unknown tool name `foo` found in scoped lint: `foo::baz`
+  --> $DIR/cross-crate.rs:7:9
+   |
+LL | #[allow(foo::baz)]
+   |         ^^^
+   |
+   = help: add `#![register_tool(foo)]` to the crate root
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0433, E0710.
+For more information about an error, try `rustc --explain E0433`.

tests/ui/tool-attributes/duplicate-tool.rs

@@ -1,15 +1,16 @@
 //@ check-pass
 #![feature(register_tool)]
+#![warn(duplicate_tools)]
 // Register a tool multiple times is okay.
 #![register_tool(foo)]
-#![register_tool(foo)]
+#![register_tool(foo)] //~ WARN [duplicate_tools]
 #![register_tool(bar)]
-#![register_attribute_tool(bar)]
+#![register_attribute_tool(bar)] //~ WARN [duplicate_tools]
 #![register_tool(baz)]
-#![register_lint_tool(baz)]
-#![register_attribute_tool(qux)]
+#![register_lint_tool(baz)] //~ WARN [duplicate_tools]
 #![register_attribute_tool(qux)]
+#![register_attribute_tool(qux)] //~ WARN [duplicate_tools]
 #![register_lint_tool(quux)]
-#![register_lint_tool(quux)]
+#![register_lint_tool(quux)] //~ WARN [duplicate_tools]
 
 fn main() {}

tests/ui/tool-attributes/duplicate-tool.stderr

@@ -0,0 +1,48 @@
+warning: duplicate tool `foo` registered
+  --> $DIR/duplicate-tool.rs:6:18
+   |
+LL | #![register_tool(foo)]
+   |                  --- already registered here
+LL | #![register_tool(foo)]
+   |                  ^^^
+   |
+note: the lint level is defined here
+  --> $DIR/duplicate-tool.rs:3:9
+   |
+LL | #![warn(duplicate_tools)]
+   |         ^^^^^^^^^^^^^^^
+
+warning: duplicate tool `bar` registered
+  --> $DIR/duplicate-tool.rs:8:28
+   |
+LL | #![register_tool(bar)]
+   |                  --- already registered here
+LL | #![register_attribute_tool(bar)]
+   |                            ^^^
+
+warning: duplicate tool `baz` registered
+  --> $DIR/duplicate-tool.rs:10:23
+   |
+LL | #![register_tool(baz)]
+   |                  --- already registered here
+LL | #![register_lint_tool(baz)]
+   |                       ^^^
+
+warning: duplicate tool `qux` registered
+  --> $DIR/duplicate-tool.rs:12:28
+   |
+LL | #![register_attribute_tool(qux)]
+   |                            --- already registered here
+LL | #![register_attribute_tool(qux)]
+   |                            ^^^
+
+warning: duplicate tool `quux` registered
+  --> $DIR/duplicate-tool.rs:14:23
+   |
+LL | #![register_lint_tool(quux)]
+   |                       ---- already registered here
+LL | #![register_lint_tool(quux)]
+   |                       ^^^^
+
+warning: 5 warnings emitted
+

tests/ui/tool-attributes/invalid-tool.rs

@@ -2,5 +2,24 @@
 
 #![register_tool(1)]
 //~^ ERROR malformed `register_tool` attribute input
+#![register_tool(_)]
+//~^ ERROR expected identifier, found reserved identifier `_`
+//~| ERROR expected identifier, found reserved identifier `_`
+//~| ERROR expected identifier, found reserved identifier `_`
+//~| ERROR malformed `register_tool` attribute input
+
+// Special path keywords cannot be used.
+#![register_tool(crate)]
+//~^ ERROR malformed `register_tool` attribute input
+#![register_tool(self)]
+//~^ ERROR malformed `register_tool` attribute input
+#![register_tool(Self)]
+//~^ ERROR malformed `register_tool` attribute input
+#![register_tool(super)]
+//~^ ERROR malformed `register_tool` attribute input
+
+// These are okay
+#![register_tool(r#type)]
+#![register_tool(铁锈)]
 
 fn main() {}