Scott Murphy Heiberg created GROOVY-12693:
---------------------------------------------

             Summary: STC: @CompileStatic/@TypeChecked on a local variable 
fails with "Unimplemented node type"
                 Key: GROOVY-12693
                 URL: https://issues.apache.org/jira/browse/GROOVY-12693
             Project: Groovy
          Issue Type: Bug
    Affects Versions: 6.0.0
            Reporter: Scott Murphy Heiberg


*Affects Version:* 6.0.0 (also 5.0.8, the GROOVY_6_0_X branch and master)
*Environment:* macOS 26.5, JDK 21.0.12 (BellSoft Liberica); groovy / groovyc 
command line, same result with GroovyShell

h3. Problem

{{@groovy.transform.CompileStatic}} and {{@groovy.transform.TypeChecked}} 
declare {{@Target({TYPE, METHOD, CONSTRUCTOR})}}. Placing one of them on a 
local variable declaration does not produce the usual annotation target 
diagnostic; the type checker reports an internal fallback message instead.

{code:groovy}
@groovy.transform.CompileStatic
int x = 1
println x
{code}

{noformat}
$ groovy local.groovy
local.groovy: 1: [Static type checking] - Unimplemented node type @ line 1, 
column 1.
   @groovy.transform.CompileStatic
   ^

1 error

$ groovyc --check --error-format=short local.groovy
local.groovy:1:1: error: [Static type checking] - Unimplemented node type
{noformat}

The same message appears with {{@TypeChecked}}, with {{def x = 1}}, {{val x = 
1}}, {{def (a, b) = [1, 2]}}, with the declaration inside a method body 
(reported at the declaration's position), and when either annotation is placed 
on a field, a property or a parameter:

{code:groovy}
class C {
    @groovy.transform.CompileStatic private int f = 1        // Unimplemented 
node type @ line 2, column 5
    void m(@groovy.transform.TypeChecked int p) { }          // Unimplemented 
node type @ line 3, column 12
}
{code}

On a loop statement (annotations on loop statements are accepted by the parser 
since 6.0.0) the transformation does not even get as far as a diagnostic:

{code:groovy}
@groovy.transform.CompileStatic
for (int i in 1..2) println i
{code}

{noformat}
General error during canonicalization: class 
org.codehaus.groovy.ast.stmt.ForStatement cannot be cast to class 
org.codehaus.groovy.ast.AnnotatedNode (...)

java.lang.ClassCastException: class org.codehaus.groovy.ast.stmt.ForStatement 
cannot be cast to class org.codehaus.groovy.ast.AnnotatedNode (...)
        at 
org.codehaus.groovy.transform.sc.StaticCompileTransformation.visit(StaticCompileTransformation.java:60)
        at 
org.codehaus.groovy.transform.ASTTransformationVisitor.visitClass(ASTTransformationVisitor.java:173)
{noformat}

For comparison, an annotation without an AST transformation gets the expected 
diagnostic:

{code:groovy}
@Override
int x = 1
{code}

{noformat}
local.groovy: 1: Annotation @java.lang.Override is not allowed on element 
LOCAL_VARIABLE
 @ line 1, column 1.
{noformat}

h3. Expected behaviour

The documentation (Semantics, "The @TypeChecked annotation" / "The 
@CompileStatic annotation") says the annotations go on a class or a method, and 
their {{@Target}} says the same. Any other placement should be rejected with 
the standard target diagnostic, as for every other annotation:

{noformat}
Annotation @groovy.transform.CompileStatic is not allowed on element 
LOCAL_VARIABLE
{noformat}

(and {{FIELD}}, {{PARAMETER}}, {{STATEMENT}} for the other placements). 
"Unimplemented node type" describes the transformation's internal dispatch, not 
the user's mistake, and the {{ClassCastException}} is a compiler crash.

h3. Cause

{{ExtendedVerifier}} does check annotation targets for local variables, fields, 
parameters and loop statements, but it runs during class generation. 
{{StaticTypesTransformation.visit}} and {{StaticCompileTransformation.visit}} 
run earlier (instruction selection); they cast {{nodes[1]}} to 
{{AnnotatedNode}} and, for anything other than a {{ClassNode}}, {{MethodNode}} 
or {{PropertyNode}}, add the "Unimplemented node type" error themselves, so 
compilation stops before the verifier ever reports the real problem. For a loop 
statement {{nodes[1]}} is a {{Statement}}, which is not an {{AnnotatedNode}}, 
hence the {{ClassCastException}}.

A pull request with regression tests follows.

h3. Versions

Reproduced on 5.0.8, 6.0.0, 6.0.1-SNAPSHOT (GROOVY_6_0_X at 7c0dcf17dd) and 
master (7.0.0-SNAPSHOT at d86ea7eb85). On 5.0.8 the loop statement variant is a 
parse error instead because statement annotations did not exist yet.



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