Merge #3229

3229: Fix a crash with non-ascii whitespace in doc-comments r=matklad a=sinkuu

2nd commit is a random drive-by cleanup.

Co-authored-by: Shotaro Yamada <sinkuu@sinkuu.xyz>

crates/ra_assists/src/lib.rs

@@ -38,7 +38,7 @@ pub struct AssistLabel {
 impl AssistLabel {
     pub(crate) fn new(label: String, id: AssistId) -> AssistLabel {
         // FIXME: make fields private, so that this invariant can't be broken
-        assert!(label.chars().next().unwrap().is_uppercase());
+        assert!(label.starts_with(|c: char| c.is_uppercase()));
         AssistLabel { label, id }
     }
 }

crates/ra_ide/src/completion/presentation.rs

@@ -135,11 +135,7 @@ fn guess_macro_braces(&self, macro_name: &str, docs: &str) -> &'static str {
             let (before, after) = (&docs[..idx], &docs[idx + s.len()..]);
             // Ensure to match the full word
             if after.starts_with('!')
-                && before
-                    .chars()
-                    .rev()
-                    .next()
-                    .map_or(true, |c| c != '_' && !c.is_ascii_alphanumeric())
+                && !before.ends_with(|c: char| c == '_' || c.is_ascii_alphanumeric())
             {
                 // It may have spaces before the braces like `foo! {}`
                 match after[1..].chars().find(|&c| !c.is_whitespace()) {

crates/ra_ide/src/hover.rs

@@ -743,4 +743,21 @@ fn foo(bar:u32) {
             &["u32"],
         );
     }
+
+    #[test]
+    fn test_hover_non_ascii_space_doc() {
+        check_hover_result(
+            "
+            //- /lib.rs
+            ///　<- `\u{3000}` here
+            fn foo() {
+            }
+
+            fn bar() {
+                fo<|>o();
+            }
+            ",
+            &["fn foo()\n```\n\n<- `\u{3000}` here"],
+        );
+    }
 }

crates/ra_mbe/src/subtree_source.rs

@@ -141,7 +141,7 @@ fn convert_literal(l: &tt::Literal) -> TtToken {
 }
 
 fn convert_ident(ident: &tt::Ident) -> TtToken {
-    let kind = if let Some('\'') = ident.text.chars().next() {
+    let kind = if ident.text.starts_with('\'') {
         LIFETIME
     } else {
         SyntaxKind::from_keyword(ident.text.as_str()).unwrap_or(IDENT)

crates/ra_syntax/src/ast/traits.rs

@@ -126,8 +126,8 @@ fn doc_comment_text(&self) -> Option<String> {
 
                 // Determine if the prefix or prefix + 1 char is stripped
                 let pos =
-                    if line.chars().nth(prefix_len).map(|c| c.is_whitespace()).unwrap_or(false) {
-                        prefix_len + 1
+                    if let Some(ws) = line.chars().nth(prefix_len).filter(|c| c.is_whitespace()) {
+                        prefix_len + ws.len_utf8()
                     } else {
                         prefix_len
                     };