--- tcl86.orig/doc/interp.n	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/doc/interp.n	2010-10-04 15:50:19.000000000 -0700
@@ -186,6 +186,17 @@
 The initial recursion limit of the slave interpreter is set to the
 current recursion limit of its parent interpreter.
 .TP
+\fBinterp\fR \fBdebug \fIpath\fR ?\fI\-frame\fR ?\fIbool\fR??
+.
+Controls whether frame-level stack information is captured in the
+slave interpreter identified by \fIpath\fR.  If no arguments are
+given, option and current setting are returned.  If \fI\-frame\fR
+is given, the debug setting is set to the given boolean if provided
+and the current setting is returned.
+This only effects the output of \fBinfo frame\fR, in that exact
+frame-level information for command invocation at the bytecode level
+is only captured with this setting on.
+.TP
 \fBinterp\fR \fBdelete \fR?\fIpath ...?\fR
 .
 Deletes zero or more interpreters given by the optional \fIpath\fR
--- tcl86.orig/doc/tclvars.n	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/doc/tclvars.n	2010-10-05 13:35:41.000000000 -0700
@@ -101,6 +101,11 @@
 .QW /
 as the path separator, regardless of platform.
 This variable is only used when initializing the \fBauto_path\fR variable.
+.TP
+\fBenv(TCL_INTERP_DEBUG_FRAME)\fR
+.
+If existing, it has the same effect as running \fBinterp debug {} -frame 1\fR
+as the very first command of each new Tcl interpreter.
 .RE
 .TP
 \fBerrorCode\fR
--- tcl86.orig/generic/tclBasic.c	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/generic/tclBasic.c	2010-10-05 13:27:24.000000000 -0700
@@ -592,6 +592,15 @@
     iPtr->resultSpace[0] = 0;
     iPtr->threadId = Tcl_GetCurrentThread();
 
+    /* TIP #378 */
+#ifdef TCL_INTERP_DEBUG_FRAME
+    iPtr->flags |= INTERP_DEBUG_FRAME;
+#else
+    if (getenv("TCL_INTERP_DEBUG_FRAME") != NULL) {
+        iPtr->flags |= INTERP_DEBUG_FRAME;
+    }
+#endif
+
     /*
      * Initialise the tables for variable traces and searches *before*
      * creating the global ns - so that the trace on errorInfo can be
--- tcl86.orig/generic/tclExecute.c	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/generic/tclExecute.c	2010-10-04 15:50:19.000000000 -0700
@@ -2076,7 +2076,9 @@
 	NRE_ASSERT(iPtr->cmdFramePtr == bcFramePtr);
 	NRE_ASSERT(TOP_CB(interp)->procPtr == TEBCreturn);
 	iPtr->cmdFramePtr = bcFramePtr->nextPtr;
+	if (iPtr->flags & INTERP_DEBUG_FRAME) {
 	TclArgumentBCRelease((Tcl_Interp *) iPtr, bcFramePtr);
+	}
 	if (codePtr->flags & TCL_BYTECODE_RECOMPILE) {
 	    iPtr->flags |= ERR_ALREADY_LOGGED;
 	    codePtr->flags &= ~TCL_BYTECODE_RECOMPILE;
@@ -2753,8 +2755,10 @@
 	bcFramePtr->data.tebc.pc = (char *) pc;
 	iPtr->cmdFramePtr = bcFramePtr;
 
+	if (iPtr->flags & INTERP_DEBUG_FRAME) {
 	TclArgumentBCEnter((Tcl_Interp *) iPtr, objv, objc,
 		codePtr, bcFramePtr, pc - codePtr->codeStart);
+	}
 
 	DECACHE_STACK_INFO();
 
--- tcl86.orig/generic/tclInterp.c	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/generic/tclInterp.c	2010-10-05 13:28:22.000000000 -0700
@@ -210,6 +210,9 @@
 			    Tcl_Obj *const objv[]);
 static Tcl_Interp *	SlaveCreate(Tcl_Interp *interp, Tcl_Obj *pathPtr,
 			    int safe);
+static int		SlaveDebugCmd(Tcl_Interp *interp,
+			    Tcl_Interp *slaveInterp,
+			    int objc, Tcl_Obj *const objv[]);
 static int		SlaveEval(Tcl_Interp *interp, Tcl_Interp *slaveInterp,
 			    int objc, Tcl_Obj *const objv[]);
 static int		SlaveExpose(Tcl_Interp *interp,
@@ -561,16 +564,18 @@
     int index;
     static const char *const options[] = {
 	"alias",	"aliases",	"bgerror",	"cancel",
-	"create",	"delete",	"eval",		"exists",
-	"expose",	"hide",		"hidden",	"issafe",
+	"create",	"debug",	"delete",
+	"eval",		"exists",	"expose",
+	"hide",		"hidden",	"issafe",
 	"invokehidden",	"limit",	"marktrusted",	"recursionlimit",
 	"slaves",	"share",	"target",	"transfer",
 	NULL
     };
     enum option {
 	OPT_ALIAS,	OPT_ALIASES,	OPT_BGERROR,	OPT_CANCEL,
-	OPT_CREATE,	OPT_DELETE,	OPT_EVAL,	OPT_EXISTS,
-	OPT_EXPOSE,	OPT_HIDE,	OPT_HIDDEN,	OPT_ISSAFE,
+	OPT_CREATE,	OPT_DEBUG,	OPT_DELETE,
+	OPT_EVAL,	OPT_EXISTS,	OPT_EXPOSE,
+	OPT_HIDE,	OPT_HIDDEN,	OPT_ISSAFE,
 	OPT_INVOKEHID,	OPT_LIMIT,	OPT_MARKTRUSTED,OPT_RECLIMIT,
 	OPT_SLAVES,	OPT_SHARE,	OPT_TARGET,	OPT_TRANSFER
     };
@@ -784,6 +789,23 @@
 	Tcl_SetObjResult(interp, slavePtr);
 	return TCL_OK;
     }
+    case OPT_DEBUG: {
+	/* TIP #378 */
+	Tcl_Interp *slaveInterp;
+
+	/*
+	 * Currently only -frame supported, otherwise ?-option ?value??
+	 */
+	if (objc < 3 || objc > 5) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "path ?-frame ?bool??");
+	    return TCL_ERROR;
+	}
+	slaveInterp = GetInterp(interp, objv[2]);
+	if (slaveInterp == NULL) {
+	    return TCL_ERROR;
+	}
+	return SlaveDebugCmd(interp, slaveInterp, objc - 3, objv + 3);
+    }
     case OPT_DELETE: {
 	int i;
 	InterpInfo *iiPtr;
@@ -2376,14 +2398,16 @@
     Tcl_Interp *slaveInterp = clientData;
     int index;
     static const char *const options[] = {
-	"alias",	"aliases",	"bgerror",	"eval",
-	"expose",	"hide",		"hidden",	"issafe",
-	"invokehidden",	"limit",	"marktrusted",	"recursionlimit", NULL
+	"alias",	"aliases",	"bgerror",	"debug",
+	"eval",		"expose",	"hide",		"hidden",
+	"issafe",	"invokehidden",	"limit",	"marktrusted",
+	"recursionlimit", NULL
     };
     enum options {
-	OPT_ALIAS,	OPT_ALIASES,	OPT_BGERROR,	OPT_EVAL,
-	OPT_EXPOSE,	OPT_HIDE,	OPT_HIDDEN,	OPT_ISSAFE,
-	OPT_INVOKEHIDDEN, OPT_LIMIT,	OPT_MARKTRUSTED, OPT_RECLIMIT
+	OPT_ALIAS,	OPT_ALIASES,	OPT_BGERROR,	OPT_DEBUG,
+	OPT_EVAL,	OPT_EXPOSE,	OPT_HIDE,	OPT_HIDDEN,
+	OPT_ISSAFE,	OPT_INVOKEHIDDEN, OPT_LIMIT,	OPT_MARKTRUSTED,
+	OPT_RECLIMIT
     };
 
     if (slaveInterp == NULL) {
@@ -2428,6 +2452,16 @@
 	    return TCL_ERROR;
 	}
 	return SlaveBgerror(interp, slaveInterp, objc - 2, objv + 2);
+    case OPT_DEBUG:
+	/*
+	 * TIP #378
+	 * Currently only -frame supported, otherwise ?-option ?value? ...?
+	 */
+	if (objc > 4) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "?-frame ?bool??");
+	    return TCL_ERROR;
+	}
+	return SlaveDebugCmd(interp, slaveInterp, objc - 2, objv + 2);
     case OPT_EVAL:
 	if (objc < 3) {
 	    Tcl_WrongNumArgs(interp, 2, objv, "arg ?arg ...?");
@@ -2591,6 +2625,75 @@
 /*
  *----------------------------------------------------------------------
  *
+ * SlaveDebugCmd -- TIP #378
+ *
+ *	Helper function to handle 'debug' command in a slave interpreter.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	May modify INTERP_DEBUG_FRAME flag in the slave.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+SlaveDebugCmd(
+    Tcl_Interp *interp,		/* Interp for error return. */
+    Tcl_Interp *slaveInterp,	/* The slave interpreter in which command
+				 * will be evaluated. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    static const char *const debugTypes[] = {
+	"-frame", NULL
+    };
+    enum DebugTypes {
+	DEBUG_TYPE_FRAME
+    };
+    int debugType;
+    Interp *iPtr;
+    Tcl_Obj *resultPtr;
+
+    iPtr = (Interp *) slaveInterp;
+    if (objc == 0) {
+	resultPtr = Tcl_NewObj();
+	Tcl_ListObjAppendElement(NULL, resultPtr,
+		Tcl_NewStringObj("-frame", -1));
+	Tcl_ListObjAppendElement(NULL, resultPtr,
+		Tcl_NewBooleanObj(iPtr->flags & INTERP_DEBUG_FRAME));
+	Tcl_SetObjResult(interp, resultPtr);
+    } else {
+	if (Tcl_GetIndexFromObj(interp, objv[0], debugTypes,
+			"debug option", 0, &debugType) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (debugType == DEBUG_TYPE_FRAME) {
+	    if (objc == 2) { /* set */
+		if (Tcl_GetBooleanFromObj(interp, objv[1], &debugType)
+			!= TCL_OK) {
+		    return TCL_ERROR;
+		}
+		/*
+		 * Quietly ignore attempts to disable interp debugging.
+		 * This is a one-way switch as frame debug info is maintained
+		 * in a stack that must be consistent once turned on.
+		 */
+		if (debugType) {
+		    iPtr->flags |= INTERP_DEBUG_FRAME;
+		}
+	    }
+	    Tcl_SetObjResult(interp,
+		    Tcl_NewBooleanObj(iPtr->flags & INTERP_DEBUG_FRAME));
+	}
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * SlaveEval --
  *
  *	Helper function to evaluate a command in a slave interpreter.
--- tcl86.orig/generic/tclInt.h	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/generic/tclInt.h	2010-10-04 15:50:19.000000000 -0700
@@ -2251,6 +2251,9 @@
  * SAFE_INTERP:		Non zero means that the current interp is a safe
  *			interp (i.e. it has only the safe commands installed,
  *			less priviledge than a regular interp).
+ * INTERP_DEBUG_FRAME:	Used for switching on various extra interpreter
+ *			debug/info mechanisms (e.g. info frame eval/uplevel
+ *			tracing) which are performance intensive.
  * INTERP_TRACE_IN_PROGRESS: Non-zero means that an interp trace is currently
  *			active; so no further trace callbacks should be
  *			invoked.
@@ -2276,6 +2279,7 @@
 
 #define DELETED				     1
 #define ERR_ALREADY_LOGGED		     4
+#define INTERP_DEBUG_FRAME		  0x10
 #define DONT_COMPILE_CMDS_INLINE	  0x20
 #define RAND_SEED_INITIALIZED		  0x40
 #define SAFE_INTERP			  0x80
--- tcl86.orig/tests/info.test	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/tests/info.test	2010-10-05 09:57:43.000000000 -0700
@@ -690,14 +690,12 @@
 ##
 # ### ### ### ######### ######### #########
 ## info frame
-
 ## Helper
 # For the more complex results we cut the file name down to remove path
 # dependencies, and we use only part of the first line of the reported
 # command. The latter is required because otherwise the whole test case may
 # appear in some results, but the result is part of the testcase. An infinite
 # string would be required to describe that. The cutting-down breaks this.
-
 proc reduce {frame} {
     set  pos [lsearch -exact $frame cmd]
     incr pos
@@ -714,7 +712,9 @@
     }
     set frame
 }
-
+proc subinterp {} { interp create sub ; interp debug sub -frame 1;
+    interp eval sub [list proc reduce [info args reduce] [info body reduce]]
+}
 ## Helper
 # Generate a stacktrace from the current location to top.  This code
 # not only depends on the exact location of things, but also on the
@@ -1363,14 +1363,14 @@
 * {type eval line 3 cmd etrace proc ::tcltest::RunTest}
 * {type source line 1361 file info.test cmd {uplevel \\#0 $script} proc ::tcltest::RunTest}} -cleanup {unset script y}
 
-test info-38.2 {location information for uplevel, dl, direct-literal} -match glob -body {
-    join [lrange [uplevel \#0 {
-	set y DL.
-	etrace
-    }] 0 2] \n
-} -result {* {type source line 728 file info.test cmd {info frame $level} proc ::etrace level 0}
-* {type source line 1369 file info.test cmd etrace proc ::tcltest::RunTest}
-* {type source line 1367 file info.test cmd uplevel\\ \\\\ proc ::tcltest::RunTest}} -cleanup {unset y}
+# 38.2 moved to bottom to not disturb other tests with the necessary changes to this one.
+
+
+
+
+
+
+
 
 test info-38.3 {location information for uplevel, dpv, direct-proc-var} -match glob -body {
     set script {
@@ -1383,15 +1383,15 @@
 * {type source line 1338 file info.test cmd {uplevel 1 $script} proc ::control}
 * {type source line 1380 file info.test cmd {control y $script} proc ::tcltest::RunTest}} -cleanup {unset script y}
 
-test info-38.4 {location information for uplevel, dpv, direct-proc-literal} -match glob -body {
-    join [lrange [control y {
-	set y DPL
-	etrace
-    }] 0 3] \n
-} -result {* {type source line 728 file info.test cmd {info frame $level} proc ::etrace level 0}
-* {type source line 1389 file info.test cmd etrace proc ::control}
-* {type source line 1338 file info.test cmd {uplevel 1 $script} proc ::control}
-* {type source line 1387 file info.test cmd control proc ::tcltest::RunTest}} -cleanup {unset y}
+# 38.4 moved to bottom to not disturb other tests with the necessary changes to this one.
+
+
+
+
+
+
+
+
 
 test info-38.5 {location information for uplevel, ppv, proc-proc-var} -match glob -body {
     join [lrange [datav] 0 4] \n
@@ -1401,13 +1401,13 @@
 * {type source line 1353 file info.test cmd {control y $script} proc ::datav level 1}
 * {type source line 1397 file info.test cmd datav proc ::tcltest::RunTest}}
 
-test info-38.6 {location information for uplevel, ppl, proc-proc-literal} -match glob -body {
-    join [lrange [datal] 0 4] \n
-} -result {* {type source line 728 file info.test cmd {info frame $level} proc ::etrace level 0}
-* {type source line 1344 file info.test cmd etrace proc ::control}
-* {type source line 1338 file info.test cmd {uplevel 1 $script} proc ::control}
-* {type source line 1342 file info.test cmd control proc ::datal level 1}
-* {type source line 1405 file info.test cmd datal proc ::tcltest::RunTest}}
+# 38.6 moved to bottom to not disturb other tests with the necessary changes to this one.
+
+
+
+
+
+
 
 testConstraint testevalex [llength [info commands testevalex]]
 test info-38.7 {location information for arg substitution} -constraints testevalex -match glob -body {
@@ -1543,18 +1543,18 @@
 } -cleanup {unset res x} -result {   type source line 1541 file info.test cmd {info frame 0} proc ::tcltest::RunTest}
 
 test info-30.13 {bs+nl in literal words, uplevel script, with nested words} -body {
-    uplevel #0 {
+    subinterp ; set res [interp eval sub { uplevel #0 {
 	if {1} \
 	    {
 		set ::res \
 		    [reduce [info frame 0]];# line 1550
 	    }
     }
-    return $res
-} -cleanup {unset res} -result {type source line 1550 file info.test cmd {info frame 0} proc ::tcltest::RunTest}
+    set res }] ; interp delete sub ; set res
+} -cleanup {unset res} -result {type source line 1550 file info.test cmd {info frame 0} level 0}
 
 test info-30.14 {bs+nl, literal word, uplevel through proc} {
-    proc abra {script} {
+    subinterp ; set res [interp eval sub { proc abra {script} {
 	uplevel 1 $script
     }
     set res [abra {
@@ -1562,7 +1562,7 @@
 [reduce [info frame 0]]";# line 1562
     }]
     rename abra {}
-    set res
+    set res }] ; interp delete sub ; set res
 } { type source line 1562 file info.test cmd {info frame 0} proc ::abra}
 
 test info-30.15 {bs+nl in literal words, nested proc body, compiled} {
@@ -1879,6 +1879,83 @@
 type source line 1859 file info.test cmd print_one proc ::test_info_frame level 1}
 
 # -------------------------------------------------------------------------
+# Tests moved to the end to not disturb other tests and their locations.
+
+test info-38.6 {location information for uplevel, ppl, proc-proc-literal} -match glob -setup {subinterp} -body {
+    interp eval sub {
+	proc etrace {} {
+	    set res {}
+	    set level [info frame]
+	    while {$level} {
+		lappend res [list $level [reduce [info frame $level]]]
+		incr level -1
+	    }
+	    return $res
+	}
+	proc control {vv script} {
+	    upvar 1 $vv var
+	    return [uplevel 1 $script]
+	}
+	proc datal {} {
+	    control y {
+		set y PPL
+		etrace
+	    }
+	}
+	join [lrange [datal] 0 4] \n
+    }
+} -result {* {type source line 1890 file info.test cmd {info frame $level} proc ::etrace level 0}
+* {type source line 1902 file info.test cmd etrace proc ::control}
+* {type source line 1897 file info.test cmd {uplevel 1 $script} proc ::control}
+* {type source line 1900 file info.test cmd control proc ::datal level 1}
+* {type source line 1905 file info.test cmd datal level 2}} -cleanup {interp delete sub}
+
+test info-38.4 {location information for uplevel, dpv, direct-proc-literal} -match glob -setup {subinterp} -body {
+    interp eval sub {
+	proc etrace {} {
+	    set res {}
+	    set level [info frame]
+	    while {$level} {
+		lappend res [list $level [reduce [info frame $level]]]
+		incr level -1
+	    }
+	    return $res
+	}
+	proc control {vv script} {
+	    upvar 1 $vv var
+	    return [uplevel 1 $script]
+	}
+	join [lrange [control y {
+	    set y DPL
+	    etrace
+	}] 0 3] \n
+    }
+} -result {* {type source line 1919 file info.test cmd {info frame $level} proc ::etrace level 0}
+* {type source line 1930 file info.test cmd etrace proc ::control}
+* {type source line 1926 file info.test cmd {uplevel 1 $script} proc ::control}
+* {type source line 1928 file info.test cmd control level 1}} -cleanup {interp delete sub}
+
+test info-38.2 {location information for uplevel, dl, direct-literal} -match glob -setup {subinterp} -body {
+    interp eval sub {
+	proc etrace {} {
+	    set res {}
+	    set level [info frame]
+	    while {$level} {
+		lappend res [list $level [reduce [info frame $level]]]
+		incr level -1
+	    }
+	    return $res
+	}
+	join [lrange [uplevel \#0 {
+	    set y DL.
+	    etrace
+	}] 0 2] \n
+    }
+} -result {* {type source line 1944 file info.test cmd {info frame $level} proc ::etrace level 0}
+* {type source line 1951 file info.test cmd etrace level 1}
+* {type source line 1949 file info.test cmd uplevel\\ \\\\ level 1}} -cleanup {interp delete sub}
+
+# -------------------------------------------------------------------------
 unset -nocomplain res
 
 # cleanup
--- tcl86.orig/tests/interp.test	2010-10-04 15:49:22.000000000 -0700
+++ tcl86/tests/interp.test	2010-10-04 15:50:19.000000000 -0700
@@ -31,7 +31,7 @@
 } -result {wrong # args: should be "interp cmd ?arg ...?"}
 test interp-1.2 {options for interp command} -returnCodes error -body {
     interp frobox
-} -result {bad option "frobox": must be alias, aliases, bgerror, cancel, create, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
+} -result {bad option "frobox": must be alias, aliases, bgerror, cancel, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
 test interp-1.3 {options for interp command} {
     interp delete
 } ""
@@ -49,13 +49,13 @@
 } -result {wrong # args: should be "interp slaves ?path?"}
 test interp-1.7 {options for interp command} -returnCodes error -body {
     interp hello
-} -result {bad option "hello": must be alias, aliases, bgerror, cancel, create, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
+} -result {bad option "hello": must be alias, aliases, bgerror, cancel, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
 test interp-1.8 {options for interp command} -returnCodes error -body {
     interp -froboz
-} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, create, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
+} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
 test interp-1.9 {options for interp command} -returnCodes error -body {
     interp -froboz -safe
-} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, create, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer} 
+} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer} 
 test interp-1.10 {options for interp command} -returnCodes error -body {
     interp target
 } -result {wrong # args: should be "interp target path alias"}
@@ -3597,6 +3597,50 @@
     interp delete a
 } -result {26 26}
 
+test interp-38.1 {interp debug one-way switch} -setup {
+    catch {interp delete a}
+    interp create a
+    interp debug a -frame 1
+} -body {
+    # TIP #3xx interp debug frame is a one-way switch
+    interp debug a -frame 0
+} -cleanup {
+    interp delete a
+} -result {1}
+test interp-38.2 {interp debug env var} -setup {
+    catch {interp delete a}
+    set ::env(TCL_INTERP_DEBUG_FRAME) 1
+    interp create a
+} -body {
+    interp debug a
+} -cleanup {
+    unset ::env(TCL_INTERP_DEBUG_FRAME)
+    interp delete a
+} -result {-frame 1}
+test interp-38.3 {interp debug wrong args} -body {
+    interp debug
+} -returnCodes {
+    error
+} -result {wrong # args: should be "interp debug path ?-frame ?bool??"}
+test interp-38.4 {interp debug basic setup} -body {
+    interp debug {}
+} -result {-frame 0}
+test interp-38.5 {interp debug basic setup} -body {
+    interp debug {} -f
+} -result {0}
+test interp-38.6 {interp debug basic setup} -body {
+    interp debug -frames
+} -returnCodes error -result {could not find interpreter "-frames"}
+test interp-38.7 {interp debug basic setup} -body {
+    interp debug {} -frames
+} -returnCodes error -result {bad debug option "-frames": must be -frame}
+test interp-38.8 {interp debug basic setup} -body {
+    interp debug {} -frame 0 bogus
+} -returnCodes {
+    error
+} -result {wrong # args: should be "interp debug path ?-frame ?bool??"}
+
+
 # cleanup
 foreach i [interp slaves] {
     interp delete $i
