Auto merge of rust-lang#85597 - 0yoyoyo:fix-issue-71563-remove-redundant-args, r=petrochenkov

bors · bors · commit b348385da189 · 2021-05-31T01:59:20.000Z
Fix span of redundant generic arguments Fixes rust-lang#71563 Above issue is about lifetime arguments, but generic arguments also have same problem. This PR fixes both help messages.
diff --git a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
@@ -605,30 +605,35 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
         let remove_entire_generics = num_redundant_args >= self.gen_args.args.len();
 
         let remove_lifetime_args = |err: &mut DiagnosticBuilder<'_>| {
-            let idx_first_redundant_lt_args = self.num_expected_lifetime_args();
-            let span_lo_redundant_lt_args =
-                self.gen_args.args[idx_first_redundant_lt_args].span().shrink_to_lo();
-            let span_hi_redundant_lt_args = self.gen_args.args
-                [idx_first_redundant_lt_args + num_redundant_lt_args - 1]
-                .span()
-                .shrink_to_hi();
-            let eat_comma =
-                idx_first_redundant_lt_args + num_redundant_lt_args - 1 != self.gen_args.args.len();
-
-            let span_redundant_lt_args = if eat_comma {
-                let span_hi = self.gen_args.args
-                    [idx_first_redundant_lt_args + num_redundant_lt_args - 1]
-                    .span()
-                    .shrink_to_hi();
-                span_lo_redundant_lt_args.to(span_hi)
-            } else {
-                span_lo_redundant_lt_args.to(span_hi_redundant_lt_args)
-            };
+            let mut lt_arg_spans = Vec::new();
+            let mut found_redundant = false;
+            for arg in self.gen_args.args {
+                if let hir::GenericArg::Lifetime(_) = arg {
+                    lt_arg_spans.push(arg.span());
+                    if lt_arg_spans.len() > self.num_expected_lifetime_args() {
+                        found_redundant = true;
+                    }
+                } else if found_redundant {
+                    // Argument which is redundant and separated like this `'c`
+                    // is not included to avoid including `Bar` in span.
+                    // ```
+                    // type Foo<'a, T> = &'a T;
+                    // let _: Foo<'a, 'b, Bar, 'c>;
+                    // ```
+                    break;
+                }
+            }
+
+            let span_lo_redundant_lt_args = lt_arg_spans[self.num_expected_lifetime_args()];
+            let span_hi_redundant_lt_args = lt_arg_spans[lt_arg_spans.len() - 1];
+
+            let span_redundant_lt_args = span_lo_redundant_lt_args.to(span_hi_redundant_lt_args);
             debug!("span_redundant_lt_args: {:?}", span_redundant_lt_args);
 
+            let num_redundant_lt_args = lt_arg_spans.len() - self.num_expected_lifetime_args();
             let msg_lifetimes = format!(
                 "remove {} {} argument{}",
-                if num_redundant_args == 1 { "this" } else { "these" },
+                if num_redundant_lt_args == 1 { "this" } else { "these" },
                 "lifetime",
                 pluralize!(num_redundant_lt_args),
             );
@@ -642,26 +647,34 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
         };
 
         let remove_type_or_const_args = |err: &mut DiagnosticBuilder<'_>| {
-            let idx_first_redundant_type_or_const_args = self.get_lifetime_args_offset()
-                + num_redundant_lt_args
-                + self.num_expected_type_or_const_args();
+            let mut gen_arg_spans = Vec::new();
+            let mut found_redundant = false;
+            for arg in self.gen_args.args {
+                match arg {
+                    hir::GenericArg::Type(_) | hir::GenericArg::Const(_) => {
+                        gen_arg_spans.push(arg.span());
+                        if gen_arg_spans.len() > self.num_expected_type_or_const_args() {
+                            found_redundant = true;
+                        }
+                    }
+                    _ if found_redundant => break,
+                    _ => {}
+                }
+            }
 
             let span_lo_redundant_type_or_const_args =
-                self.gen_args.args[idx_first_redundant_type_or_const_args].span().shrink_to_lo();
-
-            let span_hi_redundant_type_or_const_args = self.gen_args.args
-                [idx_first_redundant_type_or_const_args + num_redundant_type_or_const_args - 1]
-                .span()
-                .shrink_to_hi();
+                gen_arg_spans[self.num_expected_type_or_const_args()];
+            let span_hi_redundant_type_or_const_args = gen_arg_spans[gen_arg_spans.len() - 1];
 
             let span_redundant_type_or_const_args =
                 span_lo_redundant_type_or_const_args.to(span_hi_redundant_type_or_const_args);
-
             debug!("span_redundant_type_or_const_args: {:?}", span_redundant_type_or_const_args);
 
+            let num_redundant_gen_args =
+                gen_arg_spans.len() - self.num_expected_type_or_const_args();
             let msg_types_or_consts = format!(
                 "remove {} {} argument{}",
-                if num_redundant_args == 1 { "this" } else { "these" },
+                if num_redundant_gen_args == 1 { "this" } else { "these" },
                 "generic",
                 pluralize!(num_redundant_type_or_const_args),
             );
diff --git a/src/test/ui/error-codes/E0107.rs b/src/test/ui/error-codes/E0107.rs
@@ -1,5 +1,7 @@
 struct Foo<'a>(&'a str);
 struct Buzz<'a, 'b>(&'a str, &'b str);
+struct Qux<'a, T>(&'a T);
+struct Quux<T>(T);
 
 enum Bar {
     A,
@@ -19,6 +21,30 @@ struct Baz<'a, 'b, 'c> {
     foo2: Foo<'a, 'b, 'c>,
     //~^ ERROR this struct takes 1 lifetime argument
     //~| HELP remove these lifetime arguments
+
+    qux1: Qux<'a, 'b, i32>,
+    //~^ ERROR this struct takes 1 lifetime argument
+    //~| HELP remove this lifetime argument
+
+    qux2: Qux<'a, i32, 'b>,
+    //~^ ERROR this struct takes 1 lifetime argument
+    //~| HELP remove this lifetime argument
+
+    qux3: Qux<'a, 'b, 'c, i32>,
+    //~^ ERROR this struct takes 1 lifetime argument
+    //~| HELP remove these lifetime arguments
+
+    qux4: Qux<'a, i32, 'b, 'c>,
+    //~^ ERROR this struct takes 1 lifetime argument
+    //~| HELP remove these lifetime arguments
+
+    qux5: Qux<'a, 'b, i32, 'c>,
+    //~^ ERROR this struct takes 1 lifetime argument
+    //~| HELP remove this lifetime argument
+
+    quux: Quux<'a, i32, 'b>,
+    //~^ ERROR this struct takes 0 lifetime arguments
+    //~| HELP remove this lifetime argument
 }
 
 fn main() {}
diff --git a/src/test/ui/error-codes/E0107.stderr b/src/test/ui/error-codes/E0107.stderr
@@ -1,5 +1,5 @@
 error[E0107]: this struct takes 2 lifetime arguments but 1 lifetime argument was supplied
-  --> $DIR/E0107.rs:11:11
+  --> $DIR/E0107.rs:13:11
    |
 LL |     buzz: Buzz<'a>,
    |           ^^^^ -- supplied 1 lifetime argument
@@ -17,21 +17,21 @@ LL |     buzz: Buzz<'a, 'a>,
    |                  ^^^^
 
 error[E0107]: this enum takes 0 lifetime arguments but 1 lifetime argument was supplied
-  --> $DIR/E0107.rs:15:10
+  --> $DIR/E0107.rs:17:10
    |
 LL |     bar: Bar<'a>,
    |          ^^^---- help: remove these generics
    |          |
    |          expected 0 lifetime arguments
    |
 note: enum defined here, with 0 lifetime parameters
-  --> $DIR/E0107.rs:4:6
+  --> $DIR/E0107.rs:6:6
    |
 LL | enum Bar {
    |      ^^^
 
 error[E0107]: this struct takes 1 lifetime argument but 3 lifetime arguments were supplied
-  --> $DIR/E0107.rs:19:11
+  --> $DIR/E0107.rs:21:11
    |
 LL |     foo2: Foo<'a, 'b, 'c>,
    |           ^^^     ------ help: remove these lifetime arguments
@@ -44,6 +44,90 @@ note: struct defined here, with 1 lifetime parameter: `'a`
 LL | struct Foo<'a>(&'a str);
    |        ^^^ --
 
-error: aborting due to 3 previous errors
+error[E0107]: this struct takes 1 lifetime argument but 2 lifetime arguments were supplied
+  --> $DIR/E0107.rs:25:11
+   |
+LL |     qux1: Qux<'a, 'b, i32>,
+   |           ^^^     -- help: remove this lifetime argument
+   |           |
+   |           expected 1 lifetime argument
+   |
+note: struct defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/E0107.rs:3:8
+   |
+LL | struct Qux<'a, T>(&'a T);
+   |        ^^^ --
+
+error[E0107]: this struct takes 1 lifetime argument but 2 lifetime arguments were supplied
+  --> $DIR/E0107.rs:29:11
+   |
+LL |     qux2: Qux<'a, i32, 'b>,
+   |           ^^^          -- help: remove this lifetime argument
+   |           |
+   |           expected 1 lifetime argument
+   |
+note: struct defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/E0107.rs:3:8
+   |
+LL | struct Qux<'a, T>(&'a T);
+   |        ^^^ --
+
+error[E0107]: this struct takes 1 lifetime argument but 3 lifetime arguments were supplied
+  --> $DIR/E0107.rs:33:11
+   |
+LL |     qux3: Qux<'a, 'b, 'c, i32>,
+   |           ^^^     ------ help: remove these lifetime arguments
+   |           |
+   |           expected 1 lifetime argument
+   |
+note: struct defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/E0107.rs:3:8
+   |
+LL | struct Qux<'a, T>(&'a T);
+   |        ^^^ --
+
+error[E0107]: this struct takes 1 lifetime argument but 3 lifetime arguments were supplied
+  --> $DIR/E0107.rs:37:11
+   |
+LL |     qux4: Qux<'a, i32, 'b, 'c>,
+   |           ^^^          ------ help: remove these lifetime arguments
+   |           |
+   |           expected 1 lifetime argument
+   |
+note: struct defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/E0107.rs:3:8
+   |
+LL | struct Qux<'a, T>(&'a T);
+   |        ^^^ --
+
+error[E0107]: this struct takes 1 lifetime argument but 3 lifetime arguments were supplied
+  --> $DIR/E0107.rs:41:11
+   |
+LL |     qux5: Qux<'a, 'b, i32, 'c>,
+   |           ^^^     -- help: remove this lifetime argument
+   |           |
+   |           expected 1 lifetime argument
+   |
+note: struct defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/E0107.rs:3:8
+   |
+LL | struct Qux<'a, T>(&'a T);
+   |        ^^^ --
+
+error[E0107]: this struct takes 0 lifetime arguments but 2 lifetime arguments were supplied
+  --> $DIR/E0107.rs:45:11
+   |
+LL |     quux: Quux<'a, i32, 'b>,
+   |           ^^^^ -- help: remove this lifetime argument
+   |           |
+   |           expected 0 lifetime arguments
+   |
+note: struct defined here, with 0 lifetime parameters
+  --> $DIR/E0107.rs:4:8
+   |
+LL | struct Quux<T>(T);
+   |        ^^^^
+
+error: aborting due to 9 previous errors
 
 For more information about this error, try `rustc --explain E0107`.
diff --git a/src/test/ui/generics/wrong-number-of-args.rs b/src/test/ui/generics/wrong-number-of-args.rs
@@ -66,6 +66,12 @@ mod lifetime_and_type {
     //~| ERROR missing lifetime specifier
     //~| HELP consider introducing
     //~| HELP add missing
+
+    type F = Ty<'static, usize, 'static, usize>;
+    //~^ ERROR this struct takes 1 lifetime argument but 2 lifetime arguments
+    //~| ERROR this struct takes 1 generic argument but 2 generic arguments
+    //~| HELP remove this lifetime argument
+    //~| HELP remove this generic argument
 }
 
 mod type_and_type_and_type {
diff --git a/src/test/ui/generics/wrong-number-of-args.stderr b/src/test/ui/generics/wrong-number-of-args.stderr
