fix: False positive syntax errors on frontmatter

crates/parser/src/grammar.rs

@@ -94,7 +94,17 @@ pub(crate) mod entry {
 
         pub(crate) fn source_file(p: &mut Parser<'_>) {
             let m = p.start();
+            // test frontmatter
+            // #!/usr/bin/env cargo
+            //
+            // ---
+            // [dependencies]
+            // clap = { version = "4.2", features = ["derive"] }
+            // ---
+            //
+            // fn main() {}
             p.eat(SHEBANG);
+            p.eat(FRONTMATTER);
             items::mod_contents(p, false);
             m.complete(p, SOURCE_FILE);
         }

crates/parser/test_data/generated/runner.rs

@@ -265,6 +265,8 @@ mod ok {
     #[test]
     fn for_type() { run_and_expect_no_errors("test_data/parser/inline/ok/for_type.rs"); }
     #[test]
+    fn frontmatter() { run_and_expect_no_errors("test_data/parser/inline/ok/frontmatter.rs"); }
+    #[test]
     fn full_range_expr() {
         run_and_expect_no_errors("test_data/parser/inline/ok/full_range_expr.rs");
     }

crates/parser/test_data/parser/inline/ok/frontmatter.rast

@@ -0,0 +1,18 @@
+SOURCE_FILE
+  SHEBANG "#!/usr/bin/env cargo\n"
+  FRONTMATTER "\n---\n[dependencies]\nclap = { version = \"4.2\", features = [\"derive\"] }\n---\n"
+  WHITESPACE "\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "main"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n"

crates/parser/test_data/parser/inline/ok/frontmatter.rs

@@ -0,0 +1,8 @@
+#!/usr/bin/env cargo
+
+---
+[dependencies]
+clap = { version = "4.2", features = ["derive"] }
+---
+
+fn main() {}