Rollup merge of #113811 - jieyouxu:fix-unused-qualifications-suggestion, r=oli-obk

Fix removal span calculation of `unused_qualifications` suggestion

Given a path such as `std::ops::Index<str>`, calculate the unnecessary qualification removal span by computing the beginning of the entire span until the ident span of the last path segment, which handles generic arguments and lifetime arguments in the last path segment. Previous logic only kept the ident span of the last path segment which is incorrect.

Closes #113808.

7 files changed, 129 insertions, 11 deletions

diff --git a/tests/ui/lint/lint-qualification.fixed b/tests/ui/lint/lint-qualification.fixed
new file mode 100644
index 00000000000..c1449301362
--- /dev/null
+++ b/tests/ui/lint/lint-qualification.fixed
@@ -0,0 +1,21 @@
+// run-rustfix
+#![deny(unused_qualifications)]
+#![allow(deprecated)]
+
+mod foo {
+    pub fn bar() {}
+}
+
+fn main() {
+    use foo::bar;
+    bar(); //~ ERROR: unnecessary qualification
+    bar();
+
+    let _ = || -> Result<(), ()> { try!(Ok(())); Ok(()) }; // issue #37345
+
+    macro_rules! m { () => {
+        $crate::foo::bar(); // issue #37357
+        ::foo::bar(); // issue #38682
+    } }
+    m!();
+}
diff --git a/tests/ui/lint/lint-qualification.rs b/tests/ui/lint/lint-qualification.rs
index 0cace0ca035..80904303559 100644
--- a/tests/ui/lint/lint-qualification.rs
+++ b/tests/ui/lint/lint-qualification.rs
@@ -1,3 +1,4 @@
+// run-rustfix
 #![deny(unused_qualifications)]
 #![allow(deprecated)]
 
diff --git a/tests/ui/lint/lint-qualification.stderr b/tests/ui/lint/lint-qualification.stderr
index d09cb78c4f0..90a06bc6cbe 100644
--- a/tests/ui/lint/lint-qualification.stderr
+++ b/tests/ui/lint/lint-qualification.stderr
@@ -1,18 +1,19 @@
 error: unnecessary qualification
-  --> $DIR/lint-qualification.rs:10:5
+  --> $DIR/lint-qualification.rs:11:5
    |
 LL |     foo::bar();
    |     ^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-qualification.rs:1:9
+  --> $DIR/lint-qualification.rs:2:9
    |
 LL | #![deny(unused_qualifications)]
    |         ^^^^^^^^^^^^^^^^^^^^^
-help: replace it with the unqualified path
+help: remove the unnecessary path segments
+   |
+LL -     foo::bar();
+LL +     bar();
    |
-LL |     bar();
-   |     ~~~
 
 error: aborting due to previous error
 
diff --git a/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.fixed b/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.fixed
new file mode 100644
index 00000000000..e730f94660b
--- /dev/null
+++ b/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.fixed
@@ -0,0 +1,31 @@
+// run-rustfix
+
+#![deny(unused_qualifications)]
+#![feature(unsized_fn_params)]
+
+#[allow(unused_imports)]
+use std::ops;
+use std::ops::Index;
+
+pub struct A;
+
+impl Index<str> for A {
+    //~^ ERROR unnecessary qualification
+    type Output = ();
+    fn index(&self, _: str) -> &Self::Output {
+        &()
+    }
+}
+
+mod inner {
+    pub trait Trait<T> {}
+}
+
+// the import needs to be here for the lint to show up
+#[allow(unused_imports)]
+use inner::Trait;
+
+impl Trait<u8> for () {}
+//~^ ERROR unnecessary qualification
+
+fn main() {}
diff --git a/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.rs b/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.rs
new file mode 100644
index 00000000000..641c892e3de
--- /dev/null
+++ b/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.rs
@@ -0,0 +1,31 @@
+// run-rustfix
+
+#![deny(unused_qualifications)]
+#![feature(unsized_fn_params)]
+
+#[allow(unused_imports)]
+use std::ops;
+use std::ops::Index;
+
+pub struct A;
+
+impl ops::Index<str> for A {
+    //~^ ERROR unnecessary qualification
+    type Output = ();
+    fn index(&self, _: str) -> &Self::Output {
+        &()
+    }
+}
+
+mod inner {
+    pub trait Trait<T> {}
+}
+
+// the import needs to be here for the lint to show up
+#[allow(unused_imports)]
+use inner::Trait;
+
+impl inner::Trait<u8> for () {}
+//~^ ERROR unnecessary qualification
+
+fn main() {}
diff --git a/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.stderr b/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.stderr
new file mode 100644
index 00000000000..d9c7fd21871
--- /dev/null
+++ b/tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.stderr
@@ -0,0 +1,31 @@
+error: unnecessary qualification
+  --> $DIR/issue-113808-invalid-unused-qualifications-suggestion.rs:12:6
+   |
+LL | impl ops::Index<str> for A {
+   |      ^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/issue-113808-invalid-unused-qualifications-suggestion.rs:3:9
+   |
+LL | #![deny(unused_qualifications)]
+   |         ^^^^^^^^^^^^^^^^^^^^^
+help: remove the unnecessary path segments
+   |
+LL - impl ops::Index<str> for A {
+LL + impl Index<str> for A {
+   |
+
+error: unnecessary qualification
+  --> $DIR/issue-113808-invalid-unused-qualifications-suggestion.rs:28:6
+   |
+LL | impl inner::Trait<u8> for () {}
+   |      ^^^^^^^^^^^^^^^^
+   |
+help: remove the unnecessary path segments
+   |
+LL - impl inner::Trait<u8> for () {}
+LL + impl Trait<u8> for () {}
+   |
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/resolve/unused-qualifications-suggestion.stderr b/tests/ui/resolve/unused-qualifications-suggestion.stderr
index c8e91e07295..e3dac37fc6e 100644
--- a/tests/ui/resolve/unused-qualifications-suggestion.stderr
+++ b/tests/ui/resolve/unused-qualifications-suggestion.stderr
@@ -9,10 +9,11 @@ note: the lint level is defined here
    |
 LL | #![deny(unused_qualifications)]
    |         ^^^^^^^^^^^^^^^^^^^^^
-help: replace it with the unqualified path
+help: remove the unnecessary path segments
+   |
+LL -     foo::bar();
+LL +     bar();
    |
-LL |     bar();
-   |     ~~~
 
 error: unnecessary qualification
   --> $DIR/unused-qualifications-suggestion.rs:21:5
@@ -20,10 +21,11 @@ error: unnecessary qualification
 LL |     baz::qux::quux();
    |     ^^^^^^^^^^^^^^
    |
-help: replace it with the unqualified path
+help: remove the unnecessary path segments
+   |
+LL -     baz::qux::quux();
+LL +     quux();
    |
-LL |     quux();
-   |     ~~~~
 
 error: aborting due to 2 previous errors