Merge #1077

1077: Improve parsing of type bounds r=matklad a=vipentti

This adds new TYPE_BOUND_LIST and TYPE_BOUND syntax kinds. These are now used when parsing type bounds. In addition parsing paths inside a bound now does not recursively parse paths, rather they are treated as separate bounds, separated by +.

Basically now the generic params `struct S<T: 'a + ?Sized + (Copy)>;` in will be parsed as 

```
TYPE_PARAM_LIST@[8; 33)
  L_ANGLE@[8; 9)
  TYPE_PARAM@[9; 32)
    NAME@[9; 10)
      IDENT@[9; 10) "T"
    COLON@[10; 11)
    WHITESPACE@[11; 12)
    TYPE_BOUND_LIST@[12; 32)
      TYPE_BOUND@[12; 14)
        LIFETIME@[12; 14) "'a"
      WHITESPACE@[14; 15)
      PLUS@[15; 16)
      WHITESPACE@[16; 17)
      TYPE_BOUND@[17; 23)
        QUESTION@[17; 18)
        PATH_TYPE@[18; 23)
          PATH@[18; 23)
            PATH_SEGMENT@[18; 23)
              NAME_REF@[18; 23)
                IDENT@[18; 23) "Sized"
      WHITESPACE@[23; 24)
      PLUS@[24; 25)
      WHITESPACE@[25; 26)
      TYPE_BOUND@[26; 32)
        L_PAREN@[26; 27)
        PATH_TYPE@[27; 31)
          PATH@[27; 31)
            PATH_SEGMENT@[27; 31)
              NAME_REF@[27; 31)
                IDENT@[27; 31) "Copy"
        R_PAREN@[31; 32)
  R_ANGLE@[32; 33)
```

Previously it was parsed, with the paths nested:

```
TYPE_PARAM_LIST@[8; 33)
  L_ANGLE@[8; 9)
  TYPE_PARAM@[9; 32)
    NAME@[9; 10)
      IDENT@[9; 10) "T"
    COLON@[10; 11)
    WHITESPACE@[11; 12)
    LIFETIME@[12; 14) "'a"
    WHITESPACE@[14; 15)
    PLUS@[15; 16)
    WHITESPACE@[16; 17)
    QUESTION@[17; 18)
    PATH_TYPE@[18; 32)
      PATH@[18; 23)
        PATH_SEGMENT@[18; 23)
          NAME_REF@[18; 23)
            IDENT@[18; 23) "Sized"
      WHITESPACE@[23; 24)
      PLUS@[24; 25)
      WHITESPACE@[25; 26)
      L_PAREN@[26; 27)
      PATH_TYPE@[27; 31)
        PATH@[27; 31)
          PATH_SEGMENT@[27; 31)
            NAME_REF@[27; 31)
              IDENT@[27; 31) "Copy"
      R_PAREN@[31; 32)
  R_ANGLE@[32; 33)
```

Looking for feedback.



Co-authored-by: Ville Penttinen <[email protected]>

1 files changed, 73 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index 47a37e4d1..9ea423b40 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -685,6 +685,7 @@ impl ToOwned for DynTraitType {
 }
 
 
+impl ast::TypeBoundsOwner for DynTraitType {}
 impl DynTraitType {}
 
 // EnumDef
@@ -1581,6 +1582,7 @@ impl ToOwned for ImplTraitType {
 }
 
 
+impl ast::TypeBoundsOwner for ImplTraitType {}
 impl ImplTraitType {}
 
 // IndexExpr
@@ -4061,6 +4063,7 @@ impl ast::NameOwner for TraitDef {}
 impl ast::AttrsOwner for TraitDef {}
 impl ast::DocCommentsOwner for TraitDef {}
 impl ast::TypeParamsOwner for TraitDef {}
+impl ast::TypeBoundsOwner for TraitDef {}
 impl TraitDef {
     pub fn item_list(&self) -> Option<&ItemList> {
         super::child_opt(self)
@@ -4291,6 +4294,7 @@ impl ast::NameOwner for TypeAliasDef {}
 impl ast::TypeParamsOwner for TypeAliasDef {}
 impl ast::AttrsOwner for TypeAliasDef {}
 impl ast::DocCommentsOwner for TypeAliasDef {}
+impl ast::TypeBoundsOwner for TypeAliasDef {}
 impl TypeAliasDef {
     pub fn type_ref(&self) -> Option<&TypeRef> {
         super::child_opt(self)
@@ -4369,6 +4373,74 @@ impl TypeArgList {
     }
 }
 
+// TypeBound
+#[derive(Debug, PartialEq, Eq, Hash)]
+#[repr(transparent)]
+pub struct TypeBound {
+    pub(crate) syntax: SyntaxNode,
+}
+unsafe impl TransparentNewType for TypeBound {
+    type Repr = rowan::SyntaxNode<RaTypes>;
+}
+
+impl AstNode for TypeBound {
+    fn cast(syntax: &SyntaxNode) -> Option<&Self> {
+        match syntax.kind() {
+            TYPE_BOUND => Some(TypeBound::from_repr(syntax.into_repr())),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode { &self.syntax }
+}
+
+impl ToOwned for TypeBound {
+    type Owned = TreeArc<TypeBound>;
+    fn to_owned(&self) -> TreeArc<TypeBound> { TreeArc::cast(self.syntax.to_owned()) }
+}
+
+
+impl TypeBound {
+    pub fn type_ref(&self) -> Option<&TypeRef> {
+        super::child_opt(self)
+    }
+
+    pub fn lifetime(&self) -> Option<&Lifetime> {
+        super::child_opt(self)
+    }
+}
+
+// TypeBoundList
+#[derive(Debug, PartialEq, Eq, Hash)]
+#[repr(transparent)]
+pub struct TypeBoundList {
+    pub(crate) syntax: SyntaxNode,
+}
+unsafe impl TransparentNewType for TypeBoundList {
+    type Repr = rowan::SyntaxNode<RaTypes>;
+}
+
+impl AstNode for TypeBoundList {
+    fn cast(syntax: &SyntaxNode) -> Option<&Self> {
+        match syntax.kind() {
+            TYPE_BOUND_LIST => Some(TypeBoundList::from_repr(syntax.into_repr())),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode { &self.syntax }
+}
+
+impl ToOwned for TypeBoundList {
+    type Owned = TreeArc<TypeBoundList>;
+    fn to_owned(&self) -> TreeArc<TypeBoundList> { TreeArc::cast(self.syntax.to_owned()) }
+}
+
+
+impl TypeBoundList {
+    pub fn bounds(&self) -> impl Iterator<Item = &TypeBound> {
+        super::children(self)
+    }
+}
+
 // TypeParam
 #[derive(Debug, PartialEq, Eq, Hash)]
 #[repr(transparent)]
@@ -4397,6 +4469,7 @@ impl ToOwned for TypeParam {
 
 impl ast::NameOwner for TypeParam {}
 impl ast::AttrsOwner for TypeParam {}
+impl ast::TypeBoundsOwner for TypeParam {}
 impl TypeParam {}
 
 // TypeParamList