Tk Source Code

Revised [text]: assertion failed in tkTextDisp.c:7191

Happens in TkTextUpdateLineMetrics():

    assert(lineNum <= endLine);

Breakpointing at this place just before the assertion, one gets the following call stack:

>	tk87tg.dll!TkTextUpdateLineMetrics(TkText * textPtr=0x03498e40, unsigned int lineNum=106, unsigned int endLine=106) 

 Line 7192	C
 	tk87tg.dll!UpdateLineMetrics(TkText * textPtr=0x03498e40, unsigned int startLine=106, unsigned int endLine=106)  

Line 1253 + 0x11 bytes	C
 	tk87tg.dll!TextWidgetObjCmd(void * clientData=0x03498e40, Tcl_Interp * interp=0x006e2270, int objc=6, Tcl_Obj * 

const * objv=0x006e6728)  Line 1873 + 0x17 bytes	C
 	tcl87tg.dll!Dispatch(void * * data=0x03bf62cc, Tcl_Interp * interp=0x006e2270, int result=0)  Line 4376 + 0x15 

bytes	C
 	tcl87tg.dll!TclNRRunCallbacks(Tcl_Interp * interp=0x006e2270, int result=0, NRE_callback * rootPtr=0x00000000)  

Line 4409 + 0x14 bytes	C
 	tcl87tg.dll!Tcl_EvalObjv(Tcl_Interp * interp=0x006e2270, int objc=3, Tcl_Obj * const * objv=0x006e64d0, int 

flags=2097168)  Line 4139 + 0x11 bytes	C
 	tcl87tg.dll!TclEvalEx(Tcl_Interp * interp=0x006e2270, const char * script=0x034e3a40, int numBytes=109, int 

flags=131072, int line=1, int * clNextOuter=0x00000000, const char * outerScript=0x034e3a40)  Line 5279 + 0x16 bytes	C
 	tcl87tg.dll!Tcl_EvalEx(Tcl_Interp * interp=0x006e2270, const char * script=0x034e3a40, int numBytes=109, int 

flags=131072)  Line 4943 + 0x1d bytes	C
 	tk87tg.dll!Tk_BindEvent(Tk_BindingTable_ * bindPtr=0x00730378, _XEvent * eventPtr=0x032e8858, Tk_Window_ * 

tkwin=0x0337a5a0, int numObjects=0, void * * objectPtr=0x002bfb84)  Line 1505 + 0x27 bytes	C
 	tk87tg.dll!TkBindEventProc(TkWindow * winPtr=0x0337a5a0, _XEvent * eventPtr=0x032e8858)  Line 317 + 0x1f bytes	C
 	tk87tg.dll!Tk_HandleEvent(_XEvent * eventPtr=0x032e8858)  Line 1374 + 0xd bytes	C
 	tk87tg.dll!WindowEventProc(Tcl_Event * evPtr=0x032e8850, int flags=-3)  Line 1764 + 0xc bytes	C
 	tcl87tg.dll!Tcl_ServiceEvent(int flags=-3)  Line 670 + 0xd bytes	C
 	tcl87tg.dll!Tcl_DoOneEvent(int flags=-3)  Line 967 + 0x9 bytes	C
 	tk87tg.dll!Tk_MainLoop()  Line 2148 + 0x11 bytes	C
 	tk87tg.dll!Tk_MainExW(int argc=-1, unsigned short * * argv=0x003b32d8, int (Tcl_Interp *)* appInitProc=0x004010e0, 

Tcl_Interp * interp=0x006e2270)  Line 391	C
 	wish87tg.exe!wWinMain(HINSTANCE__ * hInstance=0x00400000, HINSTANCE__ * hPrevInstance=0x00000000, unsigned short * 

lpszCmdLine=0x006a16b6, int nCmdShow=10)  Line 150 + 0x39 bytes	C
 	wish87tg.exe!__tmainCRTStartup()  Line 574 + 0x35 bytes	C
 	wish87tg.exe!wWinMainCRTStartup()  Line 399	C
 	kernel32.dll!7642f964() 	
 	[Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll]	
 	ntdll.dll!7703e369() 	
 	ntdll.dll!7703e57b() 	

This shows that the command currently executed was ".text count -update -ypixels", with the "indexFrom" and "indexTo" being identical, which triggers the assertion.

The call to:

    UpdateLineMetrics(textPtr, from, to);

Perhaps adding this test would be enough to fix the issue.

This is fully repeatable in my application. I can try to produce a short demo script if needed.

Thanks for the information, I did an upgrade to Fossil 12.3.

I've committed [c694fc877a] with an additional fix, UpdateLineMetrics() should be called with from < to.

I saw this also during the past week. I didn't try to investigate the root cause and Google did not spot relevant matches. I noticed that I was using an old fossil version  (1.2 IIRC, that is available from the Debian stable repo) and upgraded it to he latest 2.3
Problem vanished then.

Yes, your fix is okay, but I see there is another bug at this place, it must be ensured that from < to, thus I've made a different fix.

But currently I have a big problem, I cannot commit, Fossil gives the following output:

Autosync:  http://[email protected]/tk
Round-trips: 1   Artifacts sent: 0  received: 0
unknown command: [igot]

I'm using a different network as before, is this a problem for Fossil?

The following patch prevents the assertion from triggering in the situation I can otherwise make it trigger repeatably in my application:

Index: generic/tkText.c
==================================================================
--- generic/tkText.c
+++ generic/tkText.c
@@ -1865,11 +1865,11 @@
                break;
            case 'y':
                if (strncmp("-ypixels", option, length) == 0) {
                    int from, to;

-                   if (update) {
+                   if (update && (TkTextIndexCompare(&indexFrom, &indexTo) != 0)) {
                        from = TkTextIndexGetLineNumber(&indexFrom, textPtr);
                        to = TkTextIndexGetLineNumber(&indexTo, textPtr);
                        UpdateLineMetrics(textPtr, from, to);
                    }
                    from = TkTextIndexYPixels(textPtr, &indexFrom);

Is this correct, or is there a better fix?