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Merged
anderseknert merged 1 commit into from
Feb 26, 2026
+99 −25
Merged

Improved redundant-existence-check #1897

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51 changes: 30 additions & 21 deletions bundle/regal/rules/bugs/redundant-existence-check/redundant_existence_check.rego
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Original file line number Diff line number Diff line change
Expand Up @@ -8,18 +8,13 @@ import data.regal.result
# METADATA
# description: check rule bodies for redundant existence checks
report contains violation if {
some rule_index, rule in input.rules
some expr_index, expr in _exprs[rule_index]
some rule_index, expr_index
expr := _static_ref_exprs[rule_index][expr_index]

expr.terms.type == "ref"

not expr.with

not rule.body[expr_index + 1].negated
ast.static_ref(expr.terms)

some term in rule.body[expr_index + 1].terms
some adjacent in [-1, 1]
some term in _exprs[rule_index][expr_index + adjacent].terms

term.type == "ref"
ast.is_terms_subset(expr.terms.value, term.value)

violation := result.fail(rego.metadata.chain(), result.ranged_from_ref(expr.terms.value))
Expand All @@ -34,37 +29,51 @@ report contains violation if {
# quite unlikely that existence checks are found there
report contains violation if {
some func in ast.functions

arg_vars := {term.value |
some term in func.head.args
term.type == "var"
}

some expr in func.body

not expr.negated
expr.terms.type == "var"

some arg in func.head.args

arg.type == "var"
arg.value == expr.terms.value
expr.terms.value in arg_vars

violation := result.fail(rego.metadata.chain(), result.location(expr.terms))
}

# METADATA
# description: check for redundant existence checks in rule head assignment
report contains violation if {
some rule_index, rule in input.rules
some rule_index
input.rules[rule_index].head.value.type == "ref"

rule.head.value.type == "ref"
head := input.rules[rule_index].head

some expr in _exprs[rule_index]

not expr.negated
expr.terms.type == "ref"
ast.is_terms_subset(expr.terms.value, rule.head.value.value)
ast.is_terms_subset(expr.terms.value, head.value.value)

violation := result.fail(rego.metadata.chain(), result.ranged_from_ref(expr.terms.value))
}

# all top-level expressions in module
_exprs[rule_index][expr_index] := expr if {
some rule_index, rule in input.rules
some expr_index, expr in rule.body
some rule_index, expr_index
input.rules[rule_index].body[expr_index]

expr := input.rules[rule_index].body[expr_index]
not expr.with
not expr.negated
}

_static_ref_exprs[rule_index][expr_index] := expr if {
some rule_index, expr_index
_exprs[rule_index][expr_index].terms.type == "ref"

expr := _exprs[rule_index][expr_index]
ast.static_ref(expr.terms)
}
73 changes: 69 additions & 4 deletions bundle/regal/rules/bugs/redundant-existence-check/redundant_existence_check_test.rego
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Expand Up @@ -16,7 +16,16 @@ test_fail_redundant_existence_check if {
"category": "bugs",
"description": "Redundant existence check",
"level": "error",
"location": {"col": 3, "file": "policy.rego", "row": 7, "text": "\t\tinput.foo", "end": {"col": 12, "row": 7}},
"location": {
"col": 3,
"file": "policy.rego",
"row": 7,
"text": "\t\tinput.foo",
"end": {
"col": 12,
"row": 7,
},
},
"related_resources": [{
"description": "documentation",
"ref": config.docs.resolve_url("$baseUrl/$category/redundant-existence-check", "bugs"),
Expand All @@ -36,7 +45,16 @@ test_fail_redundant_existence_check_subset if {
"category": "bugs",
"description": "Redundant existence check",
"level": "error",
"location": {"col": 3, "file": "policy.rego", "row": 7, "text": "\t\tinput.foo", "end": {"col": 12, "row": 7}},
"location": {
"col": 3,
"file": "policy.rego",
"row": 7,
"text": "\t\tinput.foo",
"end": {
"col": 12,
"row": 7,
},
},
"related_resources": [{
"description": "documentation",
"ref": config.docs.resolve_url("$baseUrl/$category/redundant-existence-check", "bugs"),
Expand Down Expand Up @@ -75,7 +93,16 @@ test_fail_redundant_existence_check_head_assignment_of_ref if {
"category": "bugs",
"description": "Redundant existence check",
"level": "error",
"location": {"col": 3, "file": "policy.rego", "row": 7, "text": "\t\tinput.foo", "end": {"col": 12, "row": 7}},
"location": {
"col": 3,
"file": "policy.rego",
"row": 7,
"text": "\t\tinput.foo",
"end": {
"col": 12,
"row": 7,
},
},
"related_resources": [{
"description": "documentation",
"ref": config.docs.resolve_url("$baseUrl/$category/redundant-existence-check", "bugs"),
Expand All @@ -94,7 +121,45 @@ test_fail_redundant_existence_check_function_arg if {
"category": "bugs",
"description": "Redundant existence check",
"level": "error",
"location": {"col": 3, "end": {"col": 6, "row": 7}, "file": "policy.rego", "row": 7, "text": "\t\tfoo"},
"location": {
"col": 3,
"end": {
"col": 6,
"row": 7,
},
"file": "policy.rego",
"row": 7,
"text": "\t\tfoo",
},
"related_resources": [{
"description": "documentation",
"ref": config.docs.resolve_url("$baseUrl/$category/redundant-existence-check", "bugs"),
}],
"title": "redundant-existence-check",
}}
}

test_fail_redundant_existence_check_function_arg_reference_after_use if {
r := rule.report with input as ast.with_rego_v1(`
fun(foo) if {
foo.type == "object"
foo.type
}`)

r == {{
"category": "bugs",
"description": "Redundant existence check",
"level": "error",
"location": {
"col": 3,
"end": {
"col": 11,
"row": 8,
},
"file": "policy.rego",
"row": 8,
"text": "\t\tfoo.type",
},
"related_resources": [{
"description": "documentation",
"ref": config.docs.resolve_url("$baseUrl/$category/redundant-existence-check", "bugs"),
Expand Down
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