Return CallInfo for unclosed call expressions

crates/ide_db/src/call_info.rs

@@ -4,8 +4,9 @@ use either::Either;
 use hir::{HasAttrs, HirDisplay, Semantics, Type};
 use stdx::format_to;
 use syntax::{
+    algo,
     ast::{self, ArgListOwner, NameOwner},
-    match_ast, AstNode, SyntaxNode, SyntaxToken, TextRange, TextSize,
+    match_ast, AstNode, Direction, SyntaxNode, SyntaxToken, TextRange, TextSize,
 };
 
 use crate::RootDatabase;
@@ -43,7 +44,12 @@ pub fn call_info(db: &RootDatabase, position: FilePosition) -> Option<CallInfo>
     let sema = Semantics::new(db);
     let file = sema.parse(position.file_id);
     let file = file.syntax();
-    let token = file.token_at_offset(position.offset).next()?;
+    let token = file
+        .token_at_offset(position.offset)
+        .left_biased()
+        // if the cursor is sandwiched between two space tokens and the call is unclosed
+        // this prevents us from leaving the CallExpression
+        .and_then(|tok| algo::skip_trivia_token(tok, Direction::Prev))?;
     let token = sema.descend_into_macros(token);
 
     let (callable, active_parameter) = call_info_impl(&sema, token)?;

crates/ide_db/src/call_info/tests.rs

@@ -522,3 +522,30 @@ fn main(f: fn(i32, f64) -> char) {
             "#]],
     )
 }
+
+#[test]
+fn call_info_for_unclosed_call() {
+    check(
+        r#"
+fn foo(foo: u32, bar: u32) {}
+fn main() {
+    foo($0
+}"#,
+        expect![[r#"
+            fn foo(foo: u32, bar: u32)
+            (<foo: u32>, bar: u32)
+        "#]],
+    );
+    // check with surrounding space
+    check(
+        r#"
+fn foo(foo: u32, bar: u32) {}
+fn main() {
+    foo( $0
+}"#,
+        expect![[r#"
+            fn foo(foo: u32, bar: u32)
+            (<foo: u32>, bar: u32)
+        "#]],
+    )
+}