Scott Murphy Heiberg created GROOVY-12740:
---------------------------------------------
Summary: groovy-contracts: a contract closure holding a return,
assert or if statement, or declaring an empty parameter list, crashes the
compiler with a NullPointerException
Key: GROOVY-12740
URL: https://issues.apache.org/jira/browse/GROOVY-12740
Project: Groovy
Issue Type: Bug
Components: groovy-contracts
Affects Versions: 6.0.0
Reporter: Scott Murphy Heiberg
A {{@Requires}}, {{@Ensures}} or {{@Invariant}} closure whose body is not a
plain expression crashes the compiler with an internal error instead of a
compile error. A closure that declares an empty parameter list with an explicit
arrow, which is a valid closure, crashes it too.
{code:groovy}
import groovy.contracts.*
class Account {
@Requires({ return amount > 0 })
// 1
// @Requires({ assert amount > 0 })
// 2
// @Requires({ if (amount <= 0) throw new
IllegalArgumentException('amount') }) // 3
// @Requires({ -> amount > 0 })
// 4
void deposit(BigDecimal amount) {}
}
{code}
Forms 1 to 3 fail with:
{noformat}
BUG! exception in phase 'semantic analysis' in source unit 'Account.groovy'
Cannot invoke
"org.codehaus.groovy.ast.expr.BooleanExpression.getNodeMetaData(Object)"
because "booleanExpression" is null
at
org.apache.groovy.contracts.generation.AssertStatementCreationUtility.getAssertionStatement(AssertStatementCreationUtility.java:85)
at
org.apache.groovy.contracts.generation.AssertStatementCreationUtility.getAssertionStatements(AssertStatementCreationUtility.java:67)
at
org.apache.groovy.contracts.ast.visitor.AnnotationClosureVisitor.replaceWithClosureClassReference(AnnotationClosureVisitor.java:250)
{noformat}
Form 4 fails with:
{noformat}
BUG! exception in phase 'semantic analysis' in source unit 'Account.groovy' null
at
org.apache.groovy.contracts.ast.visitor.AnnotationClosureVisitor.replaceWithClosureClassReference(AnnotationClosureVisitor.java:236)
{noformat}
{{@Ensures}} and class-level {{@Invariant}} fail the same way with the same
bodies, and so does {{@Invariant}} on a loop (reported as "unexpected
NullPointerException").
h3. Cause
{{ExpressionUtils.getBooleanExpression}} builds the condition list from the
closure's statements and adds a null entry for every statement that is not an
expression statement, and {{ClosureExpressionValidator}} never checks statement
kinds, so the null reaches {{AssertStatementCreationUtility}}. For form 4,
{{ClosureExpression.getParameters()}} returns null (its documented value for a
closure with no parameters at all, as opposed to the empty array for an
implicit {{it}}) and {{AnnotationClosureVisitor}} passes it to
{{Arrays.asList}}.
h3. Expected
Forms 1 to 3 report a compile error that names the statement kind, for example
{noformat}
[groovy-contracts] Annotation closure may only contain boolean expressions;
return statements are not supported (e.g. use '@Requires({ argument1 > 0 })').
{noformat}
and form 4 compiles and behaves exactly like the closure without the arrow (a
{{PreconditionViolation}} for {{deposit(-1)}}). A {{return}} is rejected rather
than taken as the condition: each statement of the closure is its own
assertion, so a return has no meaning in that list.
Reproduced on Groovy 6.0.0 and on master (df1fe66ed1). Pull request to follow.
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