Fix parsing lambdas with return type

We should eat only a single block, and not whatever larger expression
may start with a block.

closes #3721

4 files changed, 75 insertions, 21 deletions

diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index 2335d99b3..0d277a586 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -230,14 +230,20 @@ fn lambda_expr(p: &mut Parser) -> CompletedMarker {
     p.eat(T![async]);
     p.eat(T![move]);
     params::param_list_closure(p);
-    if opt_fn_ret_type(p) && !p.at(T!['{']) {
-        p.error("expected `{`");
-    }
-
-    if p.at_ts(EXPR_FIRST) {
-        expr(p);
+    if opt_fn_ret_type(p) {
+        if p.at(T!['{']) {
+            // test lambda_ret_block
+            // fn main() { || -> i32 { 92 }(); }
+            block_expr(p, None);
+        } else {
+            p.error("expected `{`");
+        }
     } else {
-        p.error("expected expression");
+        if p.at_ts(EXPR_FIRST) {
+            expr(p);
+        } else {
+            p.error("expected expression");
+        }
     }
     m.complete(p, LAMBDA_EXPR)
 }
diff --git a/crates/ra_syntax/test_data/parser/err/0010_unsafe_lambda_block.txt b/crates/ra_syntax/test_data/parser/err/0010_unsafe_lambda_block.txt
index e0edf6a2d..0ffbd25aa 100644
--- a/crates/ra_syntax/test_data/parser/err/0010_unsafe_lambda_block.txt
+++ b/crates/ra_syntax/test_data/parser/err/0010_unsafe_lambda_block.txt
@@ -12,8 +12,8 @@ SOURCE_FILE@[0; 42)
       BLOCK@[10; 41)
         L_CURLY@[10; 11) "{"
         WHITESPACE@[11; 16) "\n    "
-        EXPR_STMT@[16; 39)
-          LAMBDA_EXPR@[16; 38)
+        EXPR_STMT@[16; 24)
+          LAMBDA_EXPR@[16; 24)
             PARAM_LIST@[16; 18)
               PIPE@[16; 17) "|"
               PIPE@[17; 18) "|"
@@ -24,20 +24,22 @@ SOURCE_FILE@[0; 42)
               TUPLE_TYPE@[22; 24)
                 L_PAREN@[22; 23) "("
                 R_PAREN@[23; 24) ")"
-            WHITESPACE@[24; 25) " "
-            BLOCK_EXPR@[25; 38)
-              UNSAFE_KW@[25; 31) "unsafe"
-              WHITESPACE@[31; 32) " "
-              BLOCK@[32; 38)
-                L_CURLY@[32; 33) "{"
-                WHITESPACE@[33; 34) " "
-                TUPLE_EXPR@[34; 36)
-                  L_PAREN@[34; 35) "("
-                  R_PAREN@[35; 36) ")"
-                WHITESPACE@[36; 37) " "
-                R_CURLY@[37; 38) "}"
+        WHITESPACE@[24; 25) " "
+        EXPR_STMT@[25; 39)
+          BLOCK_EXPR@[25; 38)
+            UNSAFE_KW@[25; 31) "unsafe"
+            WHITESPACE@[31; 32) " "
+            BLOCK@[32; 38)
+              L_CURLY@[32; 33) "{"
+              WHITESPACE@[33; 34) " "
+              TUPLE_EXPR@[34; 36)
+                L_PAREN@[34; 35) "("
+                R_PAREN@[35; 36) ")"
+              WHITESPACE@[36; 37) " "
+              R_CURLY@[37; 38) "}"
           SEMI@[38; 39) ";"
         WHITESPACE@[39; 40) "\n"
         R_CURLY@[40; 41) "}"
   WHITESPACE@[41; 42) "\n"
 error [24; 24): expected `{`
+error [24; 24): expected SEMI
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0158_lambda_ret_block.rs b/crates/ra_syntax/test_data/parser/inline/ok/0158_lambda_ret_block.rs
new file mode 100644
index 000000000..061118d3a
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0158_lambda_ret_block.rs
@@ -0,0 +1 @@
+fn main() { || -> i32 { 92 }(); }
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0158_lambda_ret_block.txt b/crates/ra_syntax/test_data/parser/inline/ok/0158_lambda_ret_block.txt
new file mode 100644
index 000000000..ba8779094
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0158_lambda_ret_block.txt
@@ -0,0 +1,45 @@
+SOURCE_FILE@[0; 34)
+  FN_DEF@[0; 33)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 7)
+      IDENT@[3; 7) "main"
+    PARAM_LIST@[7; 9)
+      L_PAREN@[7; 8) "("
+      R_PAREN@[8; 9) ")"
+    WHITESPACE@[9; 10) " "
+    BLOCK_EXPR@[10; 33)
+      BLOCK@[10; 33)
+        L_CURLY@[10; 11) "{"
+        WHITESPACE@[11; 12) " "
+        EXPR_STMT@[12; 31)
+          CALL_EXPR@[12; 30)
+            LAMBDA_EXPR@[12; 28)
+              PARAM_LIST@[12; 14)
+                PIPE@[12; 13) "|"
+                PIPE@[13; 14) "|"
+              WHITESPACE@[14; 15) " "
+              RET_TYPE@[15; 21)
+                THIN_ARROW@[15; 17) "->"
+                WHITESPACE@[17; 18) " "
+                PATH_TYPE@[18; 21)
+                  PATH@[18; 21)
+                    PATH_SEGMENT@[18; 21)
+                      NAME_REF@[18; 21)
+                        IDENT@[18; 21) "i32"
+              WHITESPACE@[21; 22) " "
+              BLOCK_EXPR@[22; 28)
+                BLOCK@[22; 28)
+                  L_CURLY@[22; 23) "{"
+                  WHITESPACE@[23; 24) " "
+                  LITERAL@[24; 26)
+                    INT_NUMBER@[24; 26) "92"
+                  WHITESPACE@[26; 27) " "
+                  R_CURLY@[27; 28) "}"
+            ARG_LIST@[28; 30)
+              L_PAREN@[28; 29) "("
+              R_PAREN@[29; 30) ")"
+          SEMI@[30; 31) ";"
+        WHITESPACE@[31; 32) " "
+        R_CURLY@[32; 33) "}"
+  WHITESPACE@[33; 34) "\n"