Jason Winnebeck created GROOVY-7918:
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Summary: Line number debug annotation missing on final return
Key: GROOVY-7918
URL: https://issues.apache.org/jira/browse/GROOVY-7918
Project: Groovy
Issue Type: Bug
Components: bytecode
Affects Versions: 2.4.7
Reporter: Jason Winnebeck
When debugging code in Groovy, if a method ends with a branching statement, the
debugger will appear to step into the method. In Groovy 2.4.7 and IntelliJ
2016.2.2, if you run the class below with no arguments and place a breakpoint
on line a, then choose to step one line, the debugger will appear to stop on
line b.
{code}
class Debugging {
public static void main(String[] args) {
a: if (args.length > 0) {
b: println "args"
}
} //line 6
}
{code}
The reason for this is in the bytecode:
{code}
L3
LINENUMBER 4 L3
ALOAD 1
LDC 1
AALOAD
LDC LDebugging;.class
LDC "args"
INVOKEINTERFACE org/codehaus/groovy/runtime/callsite/CallSite.callStatic
(Ljava/lang/Class;Ljava/lang/Object;)Ljava/lang/Object;
POP
L2
RETURN
{code}
There's no LINENUMBER annotation on the final return, so the LINENUMBER 4 from
earlier is used, which is inside the if block, even though the if block does
not run.
In Java, the final return is annotated with the line number of the closing
brace, which in the example above is line 6.
A workaround is to add an explicit "return" statement at the end of the method,
which generates the line number annotation without changing the semantics.
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