Repository: rust-analyzer/rust-analyzer (rust)

Issue:
Parse error when passing `loop {}` as argument
The code:
```rust
fn foo(x: i32) {}

fn main() {
    foo(loop {});
}
```
Will error with:
```
Syntax Error: expected expression (on `l` of `loop`)
Syntax Error: expected SEMI (on `)` of `foo(loop {})`)
```


Pull request:
Support loop as argument
Fixes #1839 

Patch:
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index 6c7fdc2cd4..457f42a26a 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -54,6 +54,7 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
         LIFETIME,
         ASYNC_KW,
         TRY_KW,
+        LOOP_KW
     ]);
 
 const EXPR_RECOVERY_SET: TokenSet = token_set![LET_KW];


Test patch:
diff --git a/crates/ra_syntax/test_data/parser/ok/0057_loop_in_call.rs b/crates/ra_syntax/test_data/parser/ok/0057_loop_in_call.rs
new file mode 100644
index 0000000000..31c12522ff
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0057_loop_in_call.rs
@@ -0,0 +1,5 @@
+fn foo(x: i32) {}
+
+fn main() {
+    foo(loop {});
+}
\ No newline at end of file
diff --git a/crates/ra_syntax/test_data/parser/ok/0057_loop_in_call.txt b/crates/ra_syntax/test_data/parser/ok/0057_loop_in_call.txt
new file mode 100644
index 0000000000..cc8c3f7ec3
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0057_loop_in_call.txt
@@ -0,0 +1,59 @@
+SOURCE_FILE@[0; 50)
+  FN_DEF@[0; 17)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 6)
+      IDENT@[3; 6) "foo"
+    PARAM_LIST@[6; 14)
+      L_PAREN@[6; 7) "("
+      PARAM@[7; 13)
+        BIND_PAT@[7; 8)
+          NAME@[7; 8)
+            IDENT@[7; 8) "x"
+        COLON@[8; 9) ":"
+        WHITESPACE@[9; 10) " "
+        PATH_TYPE@[10; 13)
+          PATH@[10; 13)
+            PATH_SEGMENT@[10; 13)
+              NAME_REF@[10; 13)
+                IDENT@[10; 13) "i32"
+      R_PAREN@[13; 14) ")"
+    WHITESPACE@[14; 15) " "
+    BLOCK_EXPR@[15; 17)
+      BLOCK@[15; 17)
+        L_CURLY@[15; 16) "{"
+        R_CURLY@[16; 17) "}"
+  WHITESPACE@[17; 19) "\n\n"
+  FN_DEF@[19; 50)
+    FN_KW@[19; 21) "fn"
+    WHITESPACE@[21; 22) " "
+    NAME@[22; 26)
+      IDENT@[22; 26) "main"
+    PARAM_LIST@[26; 28)
+      L_PAREN@[26; 27) "("
+      R_PAREN@[27; 28) ")"
+    WHITESPACE@[28; 29) " "
+    BLOCK_EXPR@[29; 50)
+      BLOCK@[29; 50)
+        L_CURLY@[29; 30) "{"
+        WHITESPACE@[30; 35) "\n    "
+        EXPR_STMT@[35; 48)
+          CALL_EXPR@[35; 47)
+            PATH_EXPR@[35; 38)
+              PATH@[35; 38)
+                PATH_SEGMENT@[35; 38)
+                  NAME_REF@[35; 38)
+                    IDENT@[35; 38) "foo"
+            ARG_LIST@[38; 47)
+              L_PAREN@[38; 39) "("
+              LOOP_EXPR@[39; 46)
+                LOOP_KW@[39; 43) "loop"
+                WHITESPACE@[43; 44) " "
+                BLOCK_EXPR@[44; 46)
+                  BLOCK@[44; 46)
+                    L_CURLY@[44; 45) "{"
+                    R_CURLY@[45; 46) "}"
+              R_PAREN@[46; 47) ")"
+          SEMI@[47; 48) ";"
+        WHITESPACE@[48; 49) "\n"
+        R_CURLY@[49; 50) "}"