From 76ddface089886c88b8b29e3893119f38ef26aab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lauren=C8=9Biu=20Nicola?= <lnicola@dend.ro>
Date: Tue, 23 Jun 2020 09:41:43 +0300
Subject: Fix panic in split and merge import assists

---
 crates/ra_assists/src/handlers/merge_imports.rs           | 12 +++++++++++-
 crates/ra_assists/src/handlers/split_import.rs            | 10 ++++++++++
 crates/ra_parser/src/grammar/paths.rs                     |  8 ++++++++
 .../test_data/parser/err/0004_use_path_bad_segment.rast   |  5 ++---
 .../test_data/parser/inline/err/0015_empty_segment.rast   | 15 +++++++++++++++
 .../test_data/parser/inline/err/0015_empty_segment.rs     |  1 +
 docs/dev/README.md                                        |  2 ++
 7 files changed, 49 insertions(+), 4 deletions(-)
 create mode 100644 crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rast
 create mode 100644 crates/ra_syntax/test_data/parser/inline/err/0015_empty_segment.rs

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 @@ SOURCE_FILE@0..12
             NAME_REF@4..7
               IDENT@4..7 "foo"
         COLON2@7..9 "::"
-        PATH_SEGMENT@9..11
-          ERROR@9..11
-            INT_NUMBER@9..11 "92"
+        ERROR@9..11
+          INT_NUMBER@9..11 "92"
     SEMICOLON@11..12 ";"
 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 @@
+SOURCE_FILE@0..13
+  USE_ITEM@0..12
+    USE_KW@0..3 "use"
+    WHITESPACE@3..4 " "
+    USE_TREE@4..12
+      PATH@4..12
+        PATH@4..9
+          PATH_SEGMENT@4..9
+            CRATE_KW@4..9 "crate"
+        COLON2@9..11 "::"
+        ERROR@11..12
+          SEMICOLON@11..12 ";"
+  WHITESPACE@12..13 "\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::;
diff --git a/docs/dev/README.md b/docs/dev/README.md
index 1b63d8223..76e1da6cf 100644
--- a/docs/dev/README.md
+++ b/docs/dev/README.md
@@ -348,6 +348,8 @@ To update test data, run with `UPDATE_EXPECTATIONS` variable:
 env UPDATE_EXPECTATIONS=1 cargo qt
 ```
 
+After adding a new inline test you need to run `cargo xtest codegen` and also update the test data as described above.
+
 # Logging
 
 Logging is done by both rust-analyzer and VS Code, so it might be tricky to
-- 
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