Rollup merge of #145378 - xizheyin:144968, r=davidtwco

Add `FnContext` in parser for diagnostic

Fixes rust-lang/rust#144968

Inspired by https://github.com/rust-lang/rust/issues/144968#issuecomment-3156094581, I implemented `FnContext` to indicate whether a function should have a self parameter, for example, whether the function is a trait method, whether it is in an impl block. And I removed the outdated note.

I made two commits to show the difference.

cc ``@estebank`` ``@djc``

r? compiler

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/ui/parser/suggest-self-in-bare-function.rs b/tests/ui/parser/suggest-self-in-bare-function.rs
new file mode 100644
index 00000000000..e7f2a12bcd0
--- /dev/null
+++ b/tests/ui/parser/suggest-self-in-bare-function.rs
@@ -0,0 +1,25 @@
+// We should not suggest `self` in bare functions.
+// And a note for RFC 1685 should not be shown.
+// See #144968
+
+//@ edition:2018
+
+fn is_even(value) -> bool { //~ ERROR expected one of `:`, `@`, or `|`, found `)`
+    value % 2 == 0
+}
+
+struct S;
+
+impl S {
+    fn is_even(value) -> bool { //~ ERROR expected one of `:`, `@`, or `|`, found `)`
+        value % 2 == 0
+    }
+}
+
+trait T {
+    fn is_even(value) -> bool { //~ ERROR expected one of `:`, `@`, or `|`, found `)`
+        value % 2 == 0
+    }
+}
+
+fn main() {}