Fix panic in split and merge import assists

6 files changed, 47 insertions, 4 deletions

diff --git a/crates/ra_assists/src/handlers/merge_imports.rs b/crates/ra_assists/src/handlers/merge_imports.rs
index 972d16241..ac0b3035c 100644
--- a/crates/ra_assists/src/handlers/merge_imports.rs
+++ b/crates/ra_assists/src/handlers/merge_imports.rs
@@ -127,7 +127,7 @@ fn first_path(path: &ast::Path) -> ast::Path {
 
 #[cfg(test)]
 mod tests {
-    use crate::tests::check_assist;
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
@@ -276,4 +276,14 @@ bar::baz};
 ",
         )
     }
+
+    #[test]
+    fn test_empty_use() {
+        check_assist_not_applicable(
+            merge_imports,
+            r"
+use std::<|>
+fn main() {}",
+        );
+    }
 }
diff --git a/crates/ra_assists/src/handlers/split_import.rs b/crates/ra_assists/src/handlers/split_import.rs
index c7a874480..38aa199a0 100644
--- a/crates/ra_assists/src/handlers/split_import.rs
+++ b/crates/ra_assists/src/handlers/split_import.rs
@@ -66,4 +66,14 @@ mod tests {
     fn issue4044() {
         check_assist_not_applicable(split_import, "use crate::<|>:::self;")
     }
+
+    #[test]
+    fn test_empty_use() {
+        check_assist_not_applicable(
+            split_import,
+            r"
+use std::<|>
+fn main() {}",
+        );
+    }
 }
diff --git a/crates/ra_parser/src/grammar/paths.rs b/crates/ra_parser/src/grammar/paths.rs
index 428aa711e..fd51189d5 100644
--- a/crates/ra_parser/src/grammar/paths.rs
+++ b/crates/ra_parser/src/grammar/paths.rs
@@ -73,8 +73,10 @@ fn path_segment(p: &mut Parser, mode: Mode, first: bool) {
         }
         p.expect(T![>]);
     } else {
+        let mut empty = true;
         if first {
             p.eat(T![::]);
+            empty = false;
         }
         match p.current() {
             IDENT => {
@@ -86,6 +88,12 @@ fn path_segment(p: &mut Parser, mode: Mode, first: bool) {
             T![self] | T![super] | T![crate] => p.bump_any(),
             _ => {
                 p.err_recover("expected identifier", items::ITEM_RECOVERY_SET);
+                if empty {
+                    // test_err empty_segment
+                    // use crate::;
+                    m.abandon(p);
+                    return;
+                }
             }
         };
     }
diff --git a/crates/ra_syntax/test_data/parser/err/0004_use_path_bad_segment.rast b/crates/ra_syntax/test_data/parser/err/0004_use_path_bad_segment.rast
index 8c6b89dc2..b3bcf472a 100644
--- a/crates/ra_syntax/test_data/parser/err/0004_use_path_bad_segment.rast
+++ b/crates/ra_syntax/test_data/parser/err/0004_use_path_bad_segment.rast
@@ -9,8 +9,7 @@ [email protected]
             [email protected]
               [email protected] "foo"
         [email protected] "::"
-        [email protected]
-          [email protected]
-            [email protected] "92"
+        [email protected]
+          [email protected] "92"
     [email protected] ";"
 error 9..9: expected identifier
diff --git a/crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rast b/crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rast
new file mode 100644
index 000000000..da8505607
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rast
@@ -0,0 +1,15 @@
+[email protected]
+  [email protected]
+    [email protected] "use"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected] "crate"
+        [email protected] "::"
+        [email protected]
+          [email protected] ";"
+  [email protected] "\n"
+error 11..11: expected identifier
+error 12..12: expected SEMICOLON
diff --git a/crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rs b/crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rs
new file mode 100644
index 000000000..7510664e1
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rs
@@ -0,0 +1 @@
+use crate::;