Improve handling of tail calls in debug info

src/core/org/luaj/lib/DebugLib.java

@@ -483,48 +483,36 @@ public class DebugLib extends LFunction {
 	private static StackInfo[] getstackinfo(LuaState vm, int level, int countlevels) {
 		StackInfo[] si = new StackInfo[countlevels];
 		int i = 0;
+		LClosure prevclosure = null;
         for (int j=vm.cc; j>=0; --j) {
 			
 			CallInfo ci = vm.calls[j];
-			int instr = ci.closure.p.code[ci.pc>0? ci.pc-1: 0];
+			LFunction f = ci.currentfunc(vm);
 
-			// java function? 
+			// java, or tailcall? 
-			if ( Lua.GET_OPCODE(instr) == Lua.OP_CALL ) {
+			if ( f != null && (! f.isClosure() || f!=prevclosure) ) {
-				int a = Lua.GETARG_A(instr);
+				if ( (level--) <= 0 ) {
-				LValue f = vm.stack[ci.base + a];
+					si[i++] = new StackInfo( vm, ci, ci.currentfunca(vm), null, f);
-				if ( f.isFunction() ) {
+					if ( i >= countlevels )
+						return si;
+				}
+			}
 					
 			// add the lua closure
-					if ( j < vm.cc ) {
 			if ( (level--) <= 0 ) {
-							CallInfo ci1 = vm.calls[j+1];
+				if (j>0 && vm.calls[j-1].currentfunc(vm) == ci.closure) {
-							LValue f1 = vm.calls[j+1].closure;
+					CallInfo caller = vm.calls[j-1];
-							if ( f != f1 )
+					int callera = caller.currentfunca(vm);
-								a = ci1.resultbase-ci.base;
+					si[i++] = new StackInfo( vm, caller, callera, ci, ci.closure);
-							si[i++] = new StackInfo( vm, ci, a, ci1, null);
+				} else {
+					si[i++] = new StackInfo( vm, null, -1, ci, ci.closure);
+				}
 				if ( i >= countlevels )
 					return si;
 			}
+			prevclosure = ci.closure;
 		}
 		
-					// is there also a java call? 
-					if ( ! f.isClosure() ) {
-						if ( (level--) <= 0 ) {
-							si[i++] = new StackInfo( vm, ci, a, null, (LFunction) f);
-							if ( i >= countlevels )
-								return si;
-						}
-					}
-					
-					// TODO: tail calls, for loops 
-				}
-			}
-		}
-			
-		// first call is a plain call with no enclosing frame
-		if ( (level--) <= 0 )
-			si[i++] = new StackInfo(vm, null, -1, vm.calls[0], null);
-		
 		return si;
 	}
 	

src/core/org/luaj/vm/CallInfo.java

@@ -54,4 +54,30 @@ public class CallInfo {
 		return -1;
 	}
 
+	/**
+	 * @param vm
+	 * @return current function executing, or null
+	 */
+	public LFunction currentfunc(LuaState vm) {
+		int a = currentfunca(vm);
+		if ( a >= 0 ) {
+			LValue v = vm.stack[base + a]; 
+			if ( v.isFunction() )
+				return (LFunction) v;
+		}
+		return null;
+	}
+
+	/**
+	 * @param vm
+	 * @return register of the current function executing, or null
+	 */
+	public int currentfunca(LuaState vm) {
+		int i = closure.p.code[pc>0? pc-1: 0];
+		int op = Lua.GET_OPCODE(i);
+		if ( op == Lua.OP_CALL || op == Lua.OP_TAILCALL )
+			return Lua.GETARG_A(i);
+		return -1;
+	}
+
 }

src/core/org/luaj/vm/LuaErrorException.java

@@ -53,14 +53,14 @@ public class LuaErrorException extends RuntimeException {
 	 * @param message message to supply
 	 */
 	public LuaErrorException(String message) {
-		this(null, message, 1);
+		this(null, message, -1);
 	}
 
 	/**
 	 * Construct the message around a specific vm and with a particular level of debug info
 	 * @param vm
 	 * @param message
-	 * @param level
+	 * @param level 0 for no message, >=1 for current call or above, -1 for most recent lua call
 	 */
 	public LuaErrorException(LuaState vm, String message, int level) {
 		super( addLineInfo( vm, message, level ) );
@@ -74,7 +74,7 @@ public class LuaErrorException extends RuntimeException {
 	 * @return
 	 */
 	private static String addLineInfo(LuaState vm, String message, int level) {
-		if ( level < 1 || message == null )
+		if ( level == 0 || message == null )
 			return message;
 		if ( vm == null ) {
 			if ( LThread.running != null )

src/core/org/luaj/vm/LuaState.java

@@ -1080,26 +1080,22 @@ public class LuaState extends Lua {
 
     /** 
      * Get the file line number info for a particular call frame.
-     * @param cindex index into call stack
+     * @param cindex index into call stack, or -1 to get first lua location
      * @return
      */
     protected String getFileLine(int level) {
+    	LClosure c = null;
         for (int j=cc; j>=0; --j) {
 			CallInfo ci = calls[j];
-			int instr = ci.closure.p.code[ci.pc>0? ci.pc-1: 0];
+			LFunction f = ci.currentfunc(this);
-			if ( Lua.GET_OPCODE(instr) == Lua.OP_CALL ) {
+			if ( f != null && (!f.isClosure() || f!=c) ) {
-				int a = Lua.GETARG_A(instr);
+				if ( level != -1 && (level--) <= 0 ) {
-				LValue f = stack[ci.base + a];
-				if ( f.isFunction() ) {
-					if ( ! f.isClosure() ) {
-						if ( (level--) <= 0 ) {
 					return "[Java]: "+f.toString();
 				}
 			}
+			c = ci.closure;
 			if ( (level--) <= 0 ) {
-						return ci.closure.p.sourceshort()+":"+ci.currentline();
+				return c.p.sourceshort()+":"+ci.currentline();
-					}
-				}
 			}
 		}
         return "";
@@ -1121,7 +1117,7 @@ public class LuaState extends Lua {
 	 * Raises an error with the default level.
 	 */
     public void error(String message) {
-    	throw new LuaErrorException( this, message, 1 );
+    	throw new LuaErrorException( this, message, -1 );
     }
 
 	/**
@@ -2462,7 +2458,7 @@ public class LuaState extends Lua {
 	    	case LUA_HOOKCOUNT:   this.pushstring("count"); break;
 	    	case LUA_HOOKCALL:    this.pushstring("call"); break;
 	    	case LUA_HOOKRET:     this.pushstring("return"); break;
-	    	case LUA_HOOKTAILRET: this.pushstring("return"); break;
+	    	case LUA_HOOKTAILRET: this.pushstring("tail return"); break;
 	    	default:
 	    		lineval = LInteger.valueOf(line);
 	    		this.pushstring("line");