5 files changed, 94 insertions, 15 deletions

diff --git a/crates/ra_ide_api/src/call_info.rs b/crates/ra_ide_api/src/call_info.rs
index c5e8d5843..29fa7d30b 100644
--- a/crates/ra_ide_api/src/call_info.rs
+++ b/crates/ra_ide_api/src/call_info.rs
@@ -28,6 +28,7 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
     let function = hir::source_binder::function_from_source(db, symbol.file_id, fn_def)?;
 
     let mut call_info = CallInfo::new(db, function, fn_def)?;
+
     // If we have a calling expression let's find which argument we are on
     let num_params = call_info.parameters.len();
     let has_self = fn_def.param_list().and_then(|l| l.self_param()).is_some();
@@ -38,18 +39,28 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
         }
     } else if num_params > 1 {
         // Count how many parameters into the call we are.
-        if let Some(ref arg_list) = calling_node.arg_list() {
+        if let Some(arg_list) = calling_node.arg_list() {
+            // Number of arguments specified at the call site
+            let num_args_at_callsite = arg_list.args().count();
+
             let arg_list_range = arg_list.syntax().range();
             if !arg_list_range.contains_inclusive(position.offset) {
                 tested_by!(call_info_bad_offset);
                 return None;
             }
 
-            let param = arg_list
-                .args()
-                .position(|arg| arg.syntax().range().contains(position.offset))
-                .or(Some(num_params - 1))
-                .unwrap();
+            let mut param = std::cmp::min(
+                num_args_at_callsite,
+                arg_list
+                    .args()
+                    .take_while(|arg| arg.syntax().range().end() < position.offset)
+                    .count(),
+            );
+
+            // If we are in a method account for `self`
+            if has_self {
+                param = param + 1;
+            }
 
             call_info.active_parameter = Some(param);
         }
@@ -156,6 +167,17 @@ fn bar() { foo(3, <|>); }"#,
     }
 
     #[test]
+    fn test_fn_signature_two_args_empty() {
+        let info = call_info(
+            r#"fn foo(x: u32, y: u32) -> u32 {x + y}
+fn bar() { foo(<|>); }"#,
+        );
+
+        assert_eq!(info.parameters, vec!("x".to_string(), "y".to_string()));
+        assert_eq!(info.active_parameter, Some(0));
+    }
+
+    #[test]
     fn test_fn_signature_for_impl() {
         let info = call_info(
             r#"struct F; impl F { pub fn new() { F{}} }
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index b82fa17cb..8dc7e44a9 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -69,6 +69,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
         L_BRACK => array_expr(p),
         PIPE => lambda_expr(p),
         MOVE_KW if la == PIPE => lambda_expr(p),
+        ASYNC_KW if la == PIPE || (la == MOVE_KW && p.nth(2) == PIPE) => lambda_expr(p),
         IF_KW => if_expr(p),
 
         LOOP_KW => loop_expr(p, None),
@@ -93,7 +94,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
                 }
             }
         }
-        ASYNC_KW if la == L_CURLY || la == MOVE_KW => {
+        ASYNC_KW if la == L_CURLY || (la == MOVE_KW && p.nth(2) == L_CURLY) => {
             let m = p.start();
             p.bump();
             p.eat(MOVE_KW);
@@ -191,10 +192,19 @@ fn array_expr(p: &mut Parser) -> CompletedMarker {
 //     || -> i32 { 92 };
 //     |x| x;
 //     move |x: i32,| x;
+//     async || {};
+//     move || {};
+//     async move || {};
 // }
 fn lambda_expr(p: &mut Parser) -> CompletedMarker {
-    assert!(p.at(PIPE) || (p.at(MOVE_KW) && p.nth(1) == PIPE));
+    assert!(
+        p.at(PIPE)
+            || (p.at(MOVE_KW) && p.nth(1) == PIPE)
+            || (p.at(ASYNC_KW) && p.nth(1) == PIPE)
+            || (p.at(ASYNC_KW) && p.nth(1) == MOVE_KW && p.nth(2) == PIPE)
+    );
     let m = p.start();
+    p.eat(ASYNC_KW);
     p.eat(MOVE_KW);
     params::param_list_opt_types(p);
     if opt_fn_ret_type(p) {
diff --git a/crates/ra_parser/src/grammar/items.rs b/crates/ra_parser/src/grammar/items.rs
index 8d8828652..c4b8ef3c7 100644
--- a/crates/ra_parser/src/grammar/items.rs
+++ b/crates/ra_parser/src/grammar/items.rs
@@ -82,7 +82,7 @@ pub(super) fn maybe_item(p: &mut Parser, m: Marker, flavor: ItemFlavor) -> Resul
     // test_err async_without_semicolon
     // fn foo() { let _ = async {} }
     has_mods |= p.eat(CONST_KW);
-    if p.at(ASYNC_KW) && p.nth(1) != L_CURLY && p.nth(1) != MOVE_KW {
+    if p.at(ASYNC_KW) && p.nth(1) != L_CURLY && p.nth(1) != MOVE_KW && p.nth(1) != PIPE {
         p.eat(ASYNC_KW);
         has_mods = true;
     }
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.rs b/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.rs
index c20d29751..075717823 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.rs
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.rs
@@ -3,4 +3,7 @@ fn foo() {
     || -> i32 { 92 };
     |x| x;
     move |x: i32,| x;
+    async || {};
+    move || {};
+    async move || {};
 }
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.txt
index 98271c233..b885d239a 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.txt
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0106_lambda_expr.txt
@@ -1,5 +1,5 @@
-SOURCE_FILE@[0; 79)
-  FN_DEF@[0; 78)
+SOURCE_FILE@[0; 134)
+  FN_DEF@[0; 133)
     FN_KW@[0; 2)
     WHITESPACE@[2; 3)
     NAME@[3; 6)
@@ -8,7 +8,7 @@ SOURCE_FILE@[0; 79)
       L_PAREN@[6; 7)
       R_PAREN@[7; 8)
     WHITESPACE@[8; 9)
-    BLOCK@[9; 78)
+    BLOCK@[9; 133)
       L_CURLY@[9; 10)
       WHITESPACE@[10; 15)
       EXPR_STMT@[15; 21)
@@ -90,6 +90,50 @@ SOURCE_FILE@[0; 79)
                 NAME_REF@[74; 75)
                   IDENT@[74; 75) "x"
         SEMI@[75; 76)
-      WHITESPACE@[76; 77)
-      R_CURLY@[77; 78)
-  WHITESPACE@[78; 79)
+      WHITESPACE@[76; 81)
+      EXPR_STMT@[81; 93)
+        LAMBDA_EXPR@[81; 92)
+          ASYNC_KW@[81; 86)
+          WHITESPACE@[86; 87)
+          PARAM_LIST@[87; 89)
+            PIPE@[87; 88)
+            PIPE@[88; 89)
+          WHITESPACE@[89; 90)
+          BLOCK_EXPR@[90; 92)
+            BLOCK@[90; 92)
+              L_CURLY@[90; 91)
+              R_CURLY@[91; 92)
+        SEMI@[92; 93)
+      WHITESPACE@[93; 98)
+      EXPR_STMT@[98; 109)
+        LAMBDA_EXPR@[98; 108)
+          MOVE_KW@[98; 102)
+          WHITESPACE@[102; 103)
+          PARAM_LIST@[103; 105)
+            PIPE@[103; 104)
+            PIPE@[104; 105)
+          WHITESPACE@[105; 106)
+          BLOCK_EXPR@[106; 108)
+            BLOCK@[106; 108)
+              L_CURLY@[106; 107)
+              R_CURLY@[107; 108)
+        SEMI@[108; 109)
+      WHITESPACE@[109; 114)
+      EXPR_STMT@[114; 131)
+        LAMBDA_EXPR@[114; 130)
+          ASYNC_KW@[114; 119)
+          WHITESPACE@[119; 120)
+          MOVE_KW@[120; 124)
+          WHITESPACE@[124; 125)
+          PARAM_LIST@[125; 127)
+            PIPE@[125; 126)
+            PIPE@[126; 127)
+          WHITESPACE@[127; 128)
+          BLOCK_EXPR@[128; 130)
+            BLOCK@[128; 130)
+              L_CURLY@[128; 129)
+              R_CURLY@[129; 130)
+        SEMI@[130; 131)
+      WHITESPACE@[131; 132)
+      R_CURLY@[132; 133)
+  WHITESPACE@[133; 134)