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]>

Author: bors[bot]

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;

crates/ra_syntax/src/ast/generated.rs

@@ -2013,6 +2013,7 @@ impl AstNode for Param {
 
 
 impl ast::TypeAscriptionOwner for Param {}
+impl ast::AttrsOwner for Param {}
 impl Param {
     pub fn pat(&self) -> Option<Pat> {
         super::child_opt(self)
@@ -2667,6 +2668,7 @@ impl AstNode for SelfParam {
 
 
 impl ast::TypeAscriptionOwner for SelfParam {}
+impl ast::AttrsOwner for SelfParam {}
 impl SelfParam {}
 
 // SlicePat

crates/ra_syntax/src/grammar.ron

@@ -642,12 +642,14 @@ Grammar(
         "SelfParam": (
             traits: [
                 "TypeAscriptionOwner",
+				"AttrsOwner",
             ]
         ),
         "Param": (
             options: [ "Pat" ],
             traits: [
                 "TypeAscriptionOwner",
+				"AttrsOwner",
             ]
         ),
         "UseItem": (

crates/ra_syntax/test_data/parser/inline/ok/0138_self_param_outer_attr.rs

@@ -0,0 +1 @@
+fn f(#[must_use] self) {}

crates/ra_syntax/test_data/parser/inline/ok/0138_self_param_outer_attr.txt

@@ -0,0 +1,23 @@
+SOURCE_FILE@[0; 26)
+  FN_DEF@[0; 25)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 4)
+      IDENT@[3; 4) "f"
+    PARAM_LIST@[4; 22)
+      L_PAREN@[4; 5) "("
+      ATTR@[5; 16)
+        POUND@[5; 6) "#"
+        TOKEN_TREE@[6; 16)
+          L_BRACK@[6; 7) "["
+          IDENT@[7; 15) "must_use"
+          R_BRACK@[15; 16) "]"
+      WHITESPACE@[16; 17) " "
+      SELF_PARAM@[17; 21)
+        SELF_KW@[17; 21) "self"
+      R_PAREN@[21; 22) ")"
+    WHITESPACE@[22; 23) " "
+    BLOCK@[23; 25)
+      L_CURLY@[23; 24) "{"
+      R_CURLY@[24; 25) "}"
+  WHITESPACE@[25; 26) "\n"

crates/ra_syntax/test_data/parser/inline/ok/0139_param_outer_arg.rs

@@ -0,0 +1 @@
+fn f(#[attr1] pat: Type) {}

crates/ra_syntax/test_data/parser/inline/ok/0139_param_outer_arg.txt

@@ -0,0 +1,32 @@
+SOURCE_FILE@[0; 28)
+  FN_DEF@[0; 27)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 4)
+      IDENT@[3; 4) "f"
+    PARAM_LIST@[4; 24)
+      L_PAREN@[4; 5) "("
+      ATTR@[5; 13)
+        POUND@[5; 6) "#"
+        TOKEN_TREE@[6; 13)
+          L_BRACK@[6; 7) "["
+          IDENT@[7; 12) "attr1"
+          R_BRACK@[12; 13) "]"
+      WHITESPACE@[13; 14) " "
+      PARAM@[14; 23)
+        BIND_PAT@[14; 17)
+          NAME@[14; 17)
+            IDENT@[14; 17) "pat"
+        COLON@[17; 18) ":"
+        WHITESPACE@[18; 19) " "
+        PATH_TYPE@[19; 23)
+          PATH@[19; 23)
+            PATH_SEGMENT@[19; 23)
+              NAME_REF@[19; 23)
+                IDENT@[19; 23) "Type"
+      R_PAREN@[23; 24) ")"
+    WHITESPACE@[24; 25) " "
+    BLOCK@[25; 27)
+      L_CURLY@[25; 26) "{"
+      R_CURLY@[26; 27) "}"
+  WHITESPACE@[27; 28) "\n"

crates/ra_syntax/test_data/parser/ok/0051_parameter_attrs.rs

@@ -0,0 +1,21 @@
+fn g1(#[attr1] #[attr2] pat: Type) {}
+fn g2(#[attr1] x: u8) {}
+
+extern "C" { fn printf(format: *const i8, #[attr] ...) -> i32; }
+
+fn foo<F: FnMut(#[attr] &mut Foo<'a>)>(){}
+
+trait Foo {
+    fn bar(#[attr] _: u64, # [attr] mut x: i32);
+}
+
+impl S {
+     fn f(#[must_use] self) {}
+     fn g1(#[attr] self) {}
+     fn g2(#[attr] &self) {}
+     fn g3<'a>(#[attr] &mut self) {}
+     fn g4<'a>(#[attr] &'a self) {}
+     fn g5<'a>(#[attr] &'a mut self) {}
+     fn c(#[attr] self: Self) {}
+     fn d(#[attr] self: Rc<Self>) {}
+}