compiler: fix parsing of arrow functions with single expression body

Ensure that an arrow function body expression is parsed with P_ASSIGN
precedence to not greedily consume comma expressions.

This ensures that an expression like

    () => 1, 2

is parsed as function [() => 1], integer [2] and not as
function [() => 1, 2].

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

2 files changed, 16 insertions, 1 deletions

diff --git a/compiler.c b/compiler.c
index 5c31409..15c8f8e 100644
--- a/compiler.c
+++ b/compiler.c
@@ -1118,7 +1118,7 @@ uc_compiler_compile_arrowfn(uc_compiler *compiler, json_object *args, bool resta
 		}
 	}
 	else {
-		uc_compiler_compile_expression(&fncompiler);
+		uc_compiler_parse_precedence(&fncompiler, P_ASSIGN);
 		uc_compiler_emit_insn(&fncompiler, 0, I_RETURN);
 	}
 
diff --git a/tests/03_bugs/08_compiler_arrow_fn_expressions b/tests/03_bugs/08_compiler_arrow_fn_expressions
new file mode 100644
index 0000000..5cd8960
--- /dev/null
+++ b/tests/03_bugs/08_compiler_arrow_fn_expressions
@@ -0,0 +1,15 @@
+Arrow functions with single expression bodies were parsed with a wrong
+precedence level, causing comma expressions to be greedily consumed.
+
+-- Testcase --
+{%
+	print({
+		a: () => 1,
+		b: () => 2
+	}, "\n");
+%}
+-- End --
+
+-- Expect stdout --
+{ "a": "() => { ... }", "b": "() => { ... }" }
+-- End --