feat: Add source location tracking to control flow markers

- Added fileName and lineNumber fields to ControlFlowMarker
- Updated RuntimeControlFlowList constructors to accept location info
- Added ControlFlowMarker.throwError() method for consistent error messages
  with source location
- Updated RuntimeCode.apply() to use marker.throwError()
- Updated loop handler to use marker.throwError()
- Removed redundant throwControlFlowError() helper method

Error messages now include exact source location where control flow originated.
Next: Update EmitControlFlow to pass actual file/line numbers.

dev/design/TAGGED_RETURN_CONTROL_FLOW.md

@@ -719,19 +719,25 @@ OUTER: for (@outer) {
       public final String label;        // For LAST/NEXT/REDO/GOTO (null for unlabeled)
       public final RuntimeScalar codeRef;  // For TAILCALL
       public final RuntimeArray args;      // For TAILCALL
+      public final String fileName;        // Source file where control flow originated
+      public final int lineNumber;         // Line number where control flow originated
 
       // Constructor for control flow (last/next/redo/goto)
-      public ControlFlowMarker(ControlFlowType type, String label) {
+      public ControlFlowMarker(ControlFlowType type, String label, String fileName, int lineNumber) {
           this.type = type;
           this.label = label;
+          this.fileName = fileName;
+          this.lineNumber = lineNumber;
           this.codeRef = null;
           this.args = null;
       }
 
       // Constructor for tail call (goto &NAME)
-      public ControlFlowMarker(RuntimeScalar codeRef, RuntimeArray args) {
+      public ControlFlowMarker(RuntimeScalar codeRef, RuntimeArray args, String fileName, int lineNumber) {
           this.type = ControlFlowType.TAILCALL;
           this.label = null;
+          this.fileName = fileName;
+          this.lineNumber = lineNumber;
           this.codeRef = codeRef;
           this.args = args;
       }

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

@@ -422,30 +422,18 @@ private static void emitControlFlowHandler(
 
             // Cast to RuntimeControlFlowList
             mv.visitTypeInsn(Opcodes.CHECKCAST, "org/perlonjava/runtime/RuntimeControlFlowList");
-            mv.visitInsn(Opcodes.DUP);
 
-            // Get control flow type
-            mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL,
+            // Get the marker field
+            mv.visitFieldInsn(Opcodes.GETFIELD,
                     "org/perlonjava/runtime/RuntimeControlFlowList",
-                    "getControlFlowType",
-                    "()Lorg/perlonjava/runtime/ControlFlowType;",
-                    false);
-            mv.visitInsn(Opcodes.DUP);
+                    "marker",
+                    "Lorg/perlonjava/runtime/ControlFlowMarker;");
 
-            // Get label
-            mv.visitInsn(Opcodes.SWAP);
+            // Call marker.throwError() - this method never returns
             mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL,
-                    "org/perlonjava/runtime/RuntimeControlFlowList",
-                    "getControlFlowLabel",
-                    "()Ljava/lang/String;",
-                    false);
-
-            // Call helper method to throw appropriate error
-            // Stack: [ControlFlowType, String label]
-            mv.visitMethodInsn(Opcodes.INVOKESTATIC,
-                    "org/perlonjava/runtime/RuntimeCode",
-                    "throwControlFlowError",
-                    "(Lorg/perlonjava/runtime/ControlFlowType;Ljava/lang/String;)V",
+                    "org/perlonjava/runtime/ControlFlowMarker",
+                    "throwError",
+                    "()V",
                     false);
 
             // Should never reach here (method throws), but add RETURN for verifier

src/main/java/org/perlonjava/runtime/ControlFlowMarker.java

@@ -17,15 +17,25 @@ public class ControlFlowMarker {
     /** The arguments for TAILCALL (goto &NAME) */
     public final RuntimeArray args;
 
+    /** Source file name where the control flow originated (for error messages) */
+    public final String fileName;
+
+    /** Line number where the control flow originated (for error messages) */
+    public final int lineNumber;
+
     /**
      * Constructor for control flow (last/next/redo/goto).
      * 
      * @param type The control flow type
      * @param label The label to jump to (null for unlabeled)
+     * @param fileName Source file name (for error messages)
+     * @param lineNumber Line number (for error messages)
      */
-    public ControlFlowMarker(ControlFlowType type, String label) {
+    public ControlFlowMarker(ControlFlowType type, String label, String fileName, int lineNumber) {
         this.type = type;
         this.label = label;
+        this.fileName = fileName;
+        this.lineNumber = lineNumber;
         this.codeRef = null;
         this.args = null;
     }
@@ -35,12 +45,45 @@ public ControlFlowMarker(ControlFlowType type, String label) {
      * 
      * @param codeRef The code reference to call
      * @param args The arguments to pass
+     * @param fileName Source file name (for error messages)
+     * @param lineNumber Line number (for error messages)
      */
-    public ControlFlowMarker(RuntimeScalar codeRef, RuntimeArray args) {
+    public ControlFlowMarker(RuntimeScalar codeRef, RuntimeArray args, String fileName, int lineNumber) {
         this.type = ControlFlowType.TAILCALL;
         this.label = null;
+        this.fileName = fileName;
+        this.lineNumber = lineNumber;
         this.codeRef = codeRef;
         this.args = args;
     }
+
+    /**
+     * Throws an appropriate PerlCompilerException for this control flow that couldn't be handled.
+     * Includes source file and line number in the error message.
+     * 
+     * @throws PerlCompilerException Always throws with contextual error message
+     */
+    public void throwError() {
+        String location = " at " + fileName + " line " + lineNumber;
+
+        if (type == ControlFlowType.TAILCALL) {
+            // Tail call should have been handled by trampoline at returnLabel
+            throw new PerlCompilerException("Tail call escaped to top level (internal error)" + location);
+        } else if (type == ControlFlowType.GOTO) {
+            if (label != null) {
+                throw new PerlCompilerException("Can't find label " + label + location);
+            } else {
+                throw new PerlCompilerException("goto must have a label" + location);
+            }
+        } else {
+            // last/next/redo
+            String operation = type.name().toLowerCase();
+            if (label != null) {
+                throw new PerlCompilerException("Label not found for \"" + operation + " " + label + "\"" + location);
+            } else {
+                throw new PerlCompilerException("Can't \"" + operation + "\" outside a loop block" + location);
+            }
+        }
+    }
 }
 

src/main/java/org/perlonjava/runtime/RuntimeCode.java

@@ -776,25 +776,8 @@ public RuntimeList apply(RuntimeArray a, int callContext) {
                 ControlFlowType cfType = cfList.getControlFlowType();
                 String label = cfList.getControlFlowLabel();
 
-                // This is a control flow statement that escaped to top level - error!
-                if (cfType == ControlFlowType.TAILCALL) {
-                    // Tail call should have been handled by trampoline at returnLabel
-                    throw new PerlCompilerException("Tail call escaped to top level (internal error) at ");
-                } else if (cfType == ControlFlowType.GOTO) {
-                    if (label != null) {
-                        throw new PerlCompilerException("Can't find label " + label + " at ");
-                    } else {
-                        throw new PerlCompilerException("goto must have a label at ");
-                    }
-                } else {
-                    // last/next/redo
-                    String operation = cfType.name().toLowerCase();
-                    if (label != null) {
-                        throw new PerlCompilerException("Label not found for \"" + operation + " " + label + "\" at ");
-                    } else {
-                        throw new PerlCompilerException("Can't \"" + operation + "\" outside a loop block at ");
-                    }
-                }
+                // Let the marker throw the error with proper source location
+                cfList.marker.throwError();
             }
 
             return result;
@@ -847,25 +830,8 @@ public RuntimeList apply(String subroutineName, RuntimeArray a, int callContext)
                 ControlFlowType cfType = cfList.getControlFlowType();
                 String label = cfList.getControlFlowLabel();
 
-                // This is a control flow statement that escaped to top level - error!
-                if (cfType == ControlFlowType.TAILCALL) {
-                    // Tail call should have been handled by trampoline at returnLabel
-                    throw new PerlCompilerException("Tail call escaped to top level (internal error) at ");
-                } else if (cfType == ControlFlowType.GOTO) {
-                    if (label != null) {
-                        throw new PerlCompilerException("Can't find label " + label + " at ");
-                    } else {
-                        throw new PerlCompilerException("goto must have a label at ");
-                    }
-                } else {
-                    // last/next/redo
-                    String operation = cfType.name().toLowerCase();
-                    if (label != null) {
-                        throw new PerlCompilerException("Label not found for \"" + operation + " " + label + "\" at ");
-                    } else {
-                        throw new PerlCompilerException("Can't \"" + operation + "\" outside a loop block at ");
-                    }
-                }
+                // Let the marker throw the error with proper source location
+                cfList.marker.throwError();
             }
 
             return result;
@@ -1003,33 +969,4 @@ public void dynamicRestoreState() {
         throw new PerlCompilerException("Can't modify anonymous subroutine");
     }
 
-    /**
-     * Helper method to throw appropriate control flow error.
-     * Called from loop handlers in main program when control flow escapes.
-     * 
-     * @param cfType The control flow type
-     * @param label The label (may be null)
-     * @throws PerlCompilerException Always throws with appropriate message
-     */
-    public static void throwControlFlowError(ControlFlowType cfType, String label) {
-        if (cfType == ControlFlowType.TAILCALL) {
-            // Tail call should have been handled by trampoline at returnLabel
-            throw new PerlCompilerException("Tail call escaped to top level (internal error) at ");
-        } else if (cfType == ControlFlowType.GOTO) {
-            if (label != null) {
-                throw new PerlCompilerException("Can't find label " + label + " at ");
-            } else {
-                throw new PerlCompilerException("goto must have a label at ");
-            }
-        } else {
-            // last/next/redo
-            String operation = cfType.name().toLowerCase();
-            if (label != null) {
-                throw new PerlCompilerException("Label not found for \"" + operation + " " + label + "\" at ");
-            } else {
-                throw new PerlCompilerException("Can't \"" + operation + "\" outside a loop block at ");
-            }
-        }
-    }
-
 }

src/main/java/org/perlonjava/runtime/RuntimeControlFlowList.java

@@ -14,21 +14,25 @@ public class RuntimeControlFlowList extends RuntimeList {
      * 
      * @param type The control flow type
      * @param label The label to jump to (null for unlabeled)
+     * @param fileName Source file name (for error messages)
+     * @param lineNumber Line number (for error messages)
      */
-    public RuntimeControlFlowList(ControlFlowType type, String label) {
+    public RuntimeControlFlowList(ControlFlowType type, String label, String fileName, int lineNumber) {
         super();
-        this.marker = new ControlFlowMarker(type, label);
+        this.marker = new ControlFlowMarker(type, label, fileName, lineNumber);
     }
 
     /**
      * Constructor for tail call (goto &NAME).
      * 
      * @param codeRef The code reference to call
      * @param args The arguments to pass
+     * @param fileName Source file name (for error messages)
+     * @param lineNumber Line number (for error messages)
      */
-    public RuntimeControlFlowList(RuntimeScalar codeRef, RuntimeArray args) {
+    public RuntimeControlFlowList(RuntimeScalar codeRef, RuntimeArray args, String fileName, int lineNumber) {
         super();
-        this.marker = new ControlFlowMarker(codeRef, args);
+        this.marker = new ControlFlowMarker(codeRef, args, fileName, lineNumber);
     }
 
     /**