Fix ICE when function argument mismatches.

2 files changed, 66 insertions, 0 deletions

diff --git a/tests/ui/fn/error-recovery-mismatch.rs b/tests/ui/fn/error-recovery-mismatch.rs
new file mode 100644
index 00000000000..a50a30c8c78
--- /dev/null
+++ b/tests/ui/fn/error-recovery-mismatch.rs
@@ -0,0 +1,20 @@
+// Used to ICE due to a size mismatch between the actual fake signature of `fold` and the
+// generated signature used reporting the parameter mismatch at the call site.
+// See issue #135124
+
+trait A  {
+    fn y(&self)
+    {
+        fn call() -> impl Sized {}
+        self.fold(call(), call());
+    }
+    fn fold<T>(&self, _: T, &self._) {}
+    //~^ ERROR unexpected `self` parameter in function
+    //~| ERROR expected one of `)` or `,`, found `.`
+    //~| ERROR identifier `self` is bound more than once in this parameter list
+    //~| WARNING anonymous parameters are deprecated
+    //~| WARNING this is accepted in the current edition
+    //~| ERROR the placeholder `_` is not allowed within types
+}
+
+fn main() {}
diff --git a/tests/ui/fn/error-recovery-mismatch.stderr b/tests/ui/fn/error-recovery-mismatch.stderr
new file mode 100644
index 00000000000..ad4652c11c1
--- /dev/null
+++ b/tests/ui/fn/error-recovery-mismatch.stderr
@@ -0,0 +1,46 @@
+error: unexpected `self` parameter in function
+  --> $DIR/error-recovery-mismatch.rs:11:29
+   |
+LL |     fn fold<T>(&self, _: T, &self._) {}
+   |                             ^^^^^ must be the first parameter of an associated function
+
+error: expected one of `)` or `,`, found `.`
+  --> $DIR/error-recovery-mismatch.rs:11:34
+   |
+LL |     fn fold<T>(&self, _: T, &self._) {}
+   |                                  ^
+   |                                  |
+   |                                  expected one of `)` or `,`
+   |                                  help: missing `,`
+
+error[E0415]: identifier `self` is bound more than once in this parameter list
+  --> $DIR/error-recovery-mismatch.rs:11:30
+   |
+LL |     fn fold<T>(&self, _: T, &self._) {}
+   |                              ^^^^ used as parameter more than once
+
+warning: anonymous parameters are deprecated and will be removed in the next edition
+  --> $DIR/error-recovery-mismatch.rs:11:35
+   |
+LL |     fn fold<T>(&self, _: T, &self._) {}
+   |                                   ^ help: try naming the parameter or explicitly ignoring it: `_: _`
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
+   = note: for more information, see issue #41686 <https://github.com/rust-lang/rust/issues/41686>
+   = note: `#[warn(anonymous_parameters)]` on by default
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/error-recovery-mismatch.rs:11:35
+   |
+LL |     fn fold<T>(&self, _: T, &self._) {}
+   |                                   ^ not allowed in type signatures
+   |
+help: use type parameters instead
+   |
+LL |     fn fold<T, U>(&self, _: T, &self.U) {}
+   |              +++                     ~
+
+error: aborting due to 4 previous errors; 1 warning emitted
+
+Some errors have detailed explanations: E0121, E0415.
+For more information about an error, try `rustc --explain E0121`.