Merge #1661

1661: Parse function parameters attributes r=matklad a=eupn

Fixes #1397. The [RFC-2565](https://github.com/rust-lang/rfcs/blob/master/text/2565-formal-function-parameter-attributes.md) specifies `#[attributes]` to function parameters:

```rust
fn foo(#[attr] a, #[unused] b, #[must_use] ...) {
    // ...
}
```

This PR adds those attributes into grammar and to the parser, extending corresponding inline tests.

Co-authored-by: Evgenii P <[email protected]>

1 files changed, 12 insertions, 1 deletions

diff --git a/crates/ra_parser/src/grammar/params.rs b/crates/ra_parser/src/grammar/params.rs
index 723b56343..0b09f1874 100644
--- a/crates/ra_parser/src/grammar/params.rs
+++ b/crates/ra_parser/src/grammar/params.rs
@@ -41,9 +41,20 @@ fn list_(p: &mut Parser, flavor: Flavor) {
     let m = p.start();
     p.bump();
     if flavor.type_required() {
+        // test self_param_outer_attr
+        // fn f(#[must_use] self) {}
+        attributes::outer_attributes(p);
         opt_self_param(p);
     }
-    while !p.at(EOF) && !p.at(ket) && !(flavor.type_required() && p.at(T![...])) {
+    while !p.at(EOF) && !p.at(ket) {
+        // test param_outer_arg
+        // fn f(#[attr1] pat: Type) {}
+        attributes::outer_attributes(p);
+
+        if flavor.type_required() && p.at(T![...]) {
+            break;
+        }
+
         if !p.at_ts(VALUE_PARAMETER_FIRST) {
             p.error("expected value parameter");
             break;