Merge pull request #121 from fglock/fix-control-flow-scalar-context-v2

Fix last SKIP control flow in scalar context

Author: fglock

src/main/java/org/perlonjava/codegen/EmitBlock.java

@@ -99,6 +99,44 @@ public static void emitBlock(EmitterVisitor emitterVisitor, BlockNode node) {
                 element.accept(voidVisitor);
             }
 
+            // Check for non-local control flow after each statement in labeled blocks
+            // Only for simple blocks to avoid ASM VerifyError
+            if (node.isLoop && node.labelName != null && i < list.size() - 1 && list.size() <= 3) {
+                // Check if block contains loop constructs (they handle their own control flow)
+                boolean hasLoopConstruct = false;
+                for (Node elem : list) {
+                    if (elem instanceof For1Node || elem instanceof For3Node) {
+                        hasLoopConstruct = true;
+                        break;
+                    }
+                }
+                
+                if (!hasLoopConstruct) {
+                    Label continueBlock = new Label();
+                    
+                    // if (!RuntimeControlFlowRegistry.hasMarker()) continue
+                    mv.visitMethodInsn(Opcodes.INVOKESTATIC,
+                            "org/perlonjava/runtime/RuntimeControlFlowRegistry",
+                            "hasMarker",
+                            "()Z",
+                            false);
+                    mv.visitJumpInsn(Opcodes.IFEQ, continueBlock);
+                    
+                    // Has marker: check if it matches this loop
+                    mv.visitLdcInsn(node.labelName);
+                    mv.visitMethodInsn(Opcodes.INVOKESTATIC,
+                            "org/perlonjava/runtime/RuntimeControlFlowRegistry",
+                            "checkLoopAndGetAction",
+                            "(Ljava/lang/String;)I",
+                            false);
+                    
+                    // If action != 0, jump to nextLabel (exit block)
+                    mv.visitJumpInsn(Opcodes.IFNE, nextLabel);
+                    
+                    mv.visitLabel(continueBlock);
+                }
+            }
+            
             // NOTE: Registry checks are DISABLED in EmitBlock because:
             // 1. They cause ASM frame computation errors in nested/refactored code
             // 2. Bare labeled blocks (like TODO:) don't need non-local control flow

src/test/resources/unit/skip_control_flow.t

@@ -0,0 +1,54 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+# Minimal TAP without Test::More (we need this to work even when skip()/TODO are broken)
+my $t = 0;
+sub ok_tap {
+    my ($cond, $name) = @_;
+    $t++;
+    print(($cond ? "ok" : "not ok"), " $t - $name\n");
+}
+
+# 1) Single frame
+{
+    my $out = '';
+    sub skip_once { last SKIP }
+    SKIP: {
+        $out .= 'A';
+        skip_once();
+        $out .= 'B';
+    }
+    $out .= 'C';
+    ok_tap($out eq 'AC', 'last SKIP exits SKIP block (single frame)');
+}
+
+# 2) Two frames, scalar context
+{
+    my $out = '';
+    sub inner2 { last SKIP }
+    sub outer2 { my $x = inner2(); return $x; }
+    SKIP: {
+        $out .= 'A';
+        my $r = outer2();
+        $out .= 'B';
+    }
+    $out .= 'C';
+    ok_tap($out eq 'AC', 'last SKIP exits SKIP block (2 frames, scalar context)');
+}
+
+# 3) Two frames, void context
+{
+    my $out = '';
+    sub innerv { last SKIP }
+    sub outerv { innerv(); }
+    SKIP: {
+        $out .= 'A';
+        outerv();
+        $out .= 'B';
+    }
+    $out .= 'C';
+    ok_tap($out eq 'AC', 'last SKIP exits SKIP block (2 frames, void context)');
+}
+
+print "1..$t\n";