4 files changed, 62 insertions, 37 deletions

diff --git a/crates/syntax/src/ast/expr_ext.rs b/crates/syntax/src/ast/expr_ext.rs
index 9253c97d0..e4a9b945c 100644
--- a/crates/syntax/src/ast/expr_ext.rs
+++ b/crates/syntax/src/ast/expr_ext.rs
@@ -22,6 +22,18 @@ impl ast::Expr {
             _ => false,
         }
     }
+
+    pub fn name_ref(&self) -> Option<ast::NameRef> {
+        if let ast::Expr::PathExpr(expr) = self {
+            let path = expr.path()?;
+            let segment = path.segment()?;
+            let name_ref = segment.name_ref()?;
+            if path.qualifier().is_none() {
+                return Some(name_ref);
+            }
+        }
+        None
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index b1578820f..876659a2b 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -25,6 +25,10 @@ pub fn assoc_item_list() -> ast::AssocItemList {
     ast_from_text("impl C for D {};")
 }
 
+pub fn impl_trait(trait_: ast::Path, ty: ast::Path) -> ast::Impl {
+    ast_from_text(&format!("impl {} for {} {{}}", trait_, ty))
+}
+
 pub fn path_segment(name_ref: ast::NameRef) -> ast::PathSegment {
     ast_from_text(&format!("use {};", name_ref))
 }
diff --git a/crates/syntax/src/ast/node_ext.rs b/crates/syntax/src/ast/node_ext.rs
index ce35ac01a..b70b840b8 100644
--- a/crates/syntax/src/ast/node_ext.rs
+++ b/crates/syntax/src/ast/node_ext.rs
@@ -203,15 +203,7 @@ impl ast::RecordExprField {
         if let Some(name_ref) = self.name_ref() {
             return Some(name_ref);
         }
-        if let Some(ast::Expr::PathExpr(expr)) = self.expr() {
-            let path = expr.path()?;
-            let segment = path.segment()?;
-            let name_ref = segment.name_ref()?;
-            if path.qualifier().is_none() {
-                return Some(name_ref);
-            }
-        }
-        None
+        self.expr()?.name_ref()
     }
 }
 
diff --git a/crates/syntax/src/ast/token_ext.rs b/crates/syntax/src/ast/token_ext.rs
index e4e512f2e..ac0326420 100644
--- a/crates/syntax/src/ast/token_ext.rs
+++ b/crates/syntax/src/ast/token_ext.rs
@@ -14,16 +14,15 @@ use crate::{
 
 impl ast::Comment {
     pub fn kind(&self) -> CommentKind {
-        kind_by_prefix(self.text())
+        CommentKind::from_text(self.text())
     }
 
     pub fn prefix(&self) -> &'static str {
-        for (prefix, k) in COMMENT_PREFIX_TO_KIND.iter() {
-            if *k == self.kind() && self.text().starts_with(prefix) {
-                return prefix;
-            }
-        }
-        unreachable!()
+        let &(prefix, _kind) = CommentKind::BY_PREFIX
+            .iter()
+            .find(|&(prefix, kind)| self.kind() == *kind && self.text().starts_with(prefix))
+            .unwrap();
+        prefix
     }
 }
 
@@ -55,29 +54,25 @@ pub enum CommentPlacement {
     Outer,
 }
 
-const COMMENT_PREFIX_TO_KIND: &[(&str, CommentKind)] = {
-    use {CommentPlacement::*, CommentShape::*};
-    &[
-        ("////", CommentKind { shape: Line, doc: None }),
-        ("///", CommentKind { shape: Line, doc: Some(Outer) }),
-        ("//!", CommentKind { shape: Line, doc: Some(Inner) }),
-        ("/**", CommentKind { shape: Block, doc: Some(Outer) }),
-        ("/*!", CommentKind { shape: Block, doc: Some(Inner) }),
-        ("//", CommentKind { shape: Line, doc: None }),
-        ("/*", CommentKind { shape: Block, doc: None }),
-    ]
-};
+impl CommentKind {
+    const BY_PREFIX: [(&'static str, CommentKind); 8] = [
+        ("/**/", CommentKind { shape: CommentShape::Block, doc: None }),
+        ("////", CommentKind { shape: CommentShape::Line, doc: None }),
+        ("///", CommentKind { shape: CommentShape::Line, doc: Some(CommentPlacement::Outer) }),
+        ("//!", CommentKind { shape: CommentShape::Line, doc: Some(CommentPlacement::Inner) }),
+        ("/**", CommentKind { shape: CommentShape::Block, doc: Some(CommentPlacement::Outer) }),
+        ("/*!", CommentKind { shape: CommentShape::Block, doc: Some(CommentPlacement::Inner) }),
+        ("//", CommentKind { shape: CommentShape::Line, doc: None }),
+        ("/*", CommentKind { shape: CommentShape::Block, doc: None }),
+    ];
 
-fn kind_by_prefix(text: &str) -> CommentKind {
-    if text == "/**/" {
-        return CommentKind { shape: CommentShape::Block, doc: None };
-    }
-    for (prefix, kind) in COMMENT_PREFIX_TO_KIND.iter() {
-        if text.starts_with(prefix) {
-            return *kind;
-        }
+    pub(crate) fn from_text(text: &str) -> CommentKind {
+        let &(_prefix, kind) = CommentKind::BY_PREFIX
+            .iter()
+            .find(|&(prefix, _kind)| text.starts_with(prefix))
+            .unwrap();
+        kind
     }
-    panic!("bad comment text: {:?}", text)
 }
 
 impl ast::Whitespace {
@@ -336,10 +331,22 @@ pub trait HasFormatSpecifier: AstToken {
                             }
                             c if c == '_' || c.is_alphabetic() => {
                                 read_identifier(&mut chars, &mut callback);
+
+                                if chars.peek().and_then(|next| next.1.as_ref().ok()).copied()
+                                    == Some('?')
+                                {
+                                    skip_char_and_emit(
+                                        &mut chars,
+                                        FormatSpecifier::QuestionMark,
+                                        &mut callback,
+                                    );
+                                }
+
                                 // can be either width (indicated by dollar sign, or type in which case
                                 // the next sign has to be `}`)
                                 let next =
                                     chars.peek().and_then(|next| next.1.as_ref().ok()).copied();
+
                                 match next {
                                     Some('$') => skip_char_and_emit(
                                         &mut chars,
@@ -422,6 +429,16 @@ pub trait HasFormatSpecifier: AstToken {
                             }
                             c if c == '_' || c.is_alphabetic() => {
                                 read_identifier(&mut chars, &mut callback);
+
+                                if chars.peek().and_then(|next| next.1.as_ref().ok()).copied()
+                                    == Some('?')
+                                {
+                                    skip_char_and_emit(
+                                        &mut chars,
+                                        FormatSpecifier::QuestionMark,
+                                        &mut callback,
+                                    );
+                                }
                             }
                             _ => {}
                         }