Fix false positive given arity mismatch in inconsistent-args

While a mismatched arg is technically still a violation, the arity mismatch should
probably be dealt with first, so let's have the compiler handle that.

Fixes #1250

Signed-off-by: Anders Eknert <[email protected]>

bundle/regal/rules/bugs/inconsistent-args/inconsistent_args.rego

@@ -24,6 +24,9 @@ report contains violation if {
 
 	some name, args_list in function_args_by_name
 
+	# leave that to the compiler
+	not _arity_mismatch(args_list)
+
 	# "Partition" the args by their position
 	by_position := [s |
 		some i, _ in args_list[0]
@@ -39,6 +42,12 @@ report contains violation if {
 	violation := result.fail(rego.metadata.chain(), result.ranged_location_between(args[0], regal.last(args)))
 }
 
+_arity_mismatch(args_list) if {
+	len := count(args_list[0])
+	some arr in args_list
+	count(arr) != len
+}
+
 _inconsistent_args(position) if {
 	named_vars := {arg.value |
 		some arg in position

bundle/regal/rules/bugs/inconsistent-args/inconsistent_args_test.rego

@@ -83,6 +83,19 @@ test_success_using_pattern_matching if {
 	r == set()
 }
 
+# this is a compiler error, so let's not flag it here
+# see https://github.com/StyraInc/regal/issues/1250
+test_success_incorrect_arity if {
+	module := ast.with_rego_v1(`
+	foo(a, b) if a == b
+	foo(a, b, c) if a > b > c
+	foo(b, a) if a == b
+	`)
+	r := rule.report with input as module
+
+	r == set()
+}
+
 expected := {
 	"category": "bugs",
 	"description": "Inconsistently named function arguments",