For III: See attached!

On Wed, 10 Nov 2021 09:00:26 -0700, Idris Samawi Hamid ادريس سماوي حامد  
<Idris.Hamid@colostate.edu> wrote:

> Dear Hans and gang,
>
> Consider the following MWE:
>
> ==============
> \definefont[ARABICFONT][file:Adobe_Naskh.ttf*arabic at 28pt]
> % \definefont[ARABICFONT][file:Amiri-Regular_0.ttf*arabic at 28pt]
> % \definefont[ARABICFONT][file:Scheherazade-Regular.ttf*arabic at 28pt]
> % \definefont[ARABICFONT][file:UthmanTN1_Ver10.otf*arabic at 28pt]
> % \definefont[ARABICFONT][file:almfixed.otf*arabic at 28pt]
>
> \disabledirectives[filters.utf.reorder]
> \noheaderandfooterlines
>
> \setupwhitespace[big]
> % \setupinterlinespace[line=4.2ex]
>
> \starttext
> % \startTEXpage[offset=1ex]
> \setupdirections[bidi=global,method=one]
> \righttoleft
> \ARABICFONT
>
> خَ‍ % a
>
> خَل
>
> % \stopTEXpage
> \stoptext
> ==============
>
> Three bugs:
>
> I. If we use start|stoptex and comment start|stopTeXpage, then both  
> lines 19 and 21 give an error:
>
> =======
> tex error       > tex error on line 20 in file ./test.tex:
>
> lua error:
>
> 	callback error: [string  
> "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2058: attempt to  
> index a number value (local 'chainstep')
> stack traceback:
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2058: in  
> upvalue 'chainrun'
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2941: in  
> function <[string  
> "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2514>
> 	(...tail calls...)
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2065: in  
> upvalue 'chainrun'
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2941: in  
> local 'handler'
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:3999: in  
> field '?'
> 	...eXt/tex/texmf-context/tex/context/base/mkxl/node-fnt.lmt:459: in  
> upvalue 'nodes_handlers_characters'
> 	[string "local tonut  = nodes.tonut..."]:23: in function <[string  
> "local tonut  = nodes.tonut..."]:12>
> 	(...tail calls...)	
>
> 10     \setupwhitespace[big]
> 11     % \setupinterlinespace[line=4.2ex]
> 12
> 13     \starttext
> 14     % \startTEXpage[offset=1ex]
> 15     \setupdirections[bidi=global,method=one]
> 16     \righttoleft
> 17     \ARABICFONT
> 18
> 19     خَ‍
> 20 >>
> 21     خَل
> 22
> 23     % \stopTEXpage
> 24     \stoptext
> =======
>
> Comment line 19 and yu will get virtually the same error.
>
> II. Using start|stopTeXpage, only line 21 gives the error:
>
> =======
> tex error       > tex error on line 22 in file ./test.tex:
>
> lua error:
>
> 	callback error: [string  
> "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2058: attempt to  
> index a number value (local 'chainstep')
> stack traceback:
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2058: in  
> upvalue 'chainrun'
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2941: in  
> function <[string  
> "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2514>
> 	(...tail calls...)
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2065: in  
> upvalue 'chainrun'
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:2941: in  
> local 'handler'
> 	[string "C:/ConTeXt/tex/texmf-context/tex/context/base..."]:3999: in  
> field '?'
> 	...eXt/tex/texmf-context/tex/context/base/mkxl/node-fnt.lmt:459: in  
> upvalue 'nodes_handlers_characters'
> 	[string "local tonut  = nodes.tonut..."]:23: in function <[string  
> "local tonut  = nodes.tonut..."]:12>
> 	(...tail calls...)	
>
> 12
> 13     % \starttext
> 14     \startTEXpage[offset=1ex]
> 15     \setupdirections[bidi=global,method=one]
> 16     \righttoleft
> 17     \ARABICFONT
> 18
> 19     خَ‍ % a
> 20
> 21     خَل
> 22 >>
> 23     \stopTEXpage
> 24     % \stoptext
> =======
>
> III Let us switch to almfixed:
>
> If you comment line 21 and use only line 19, then there is no tex error,  
> but the result is rendered incorrectly - see test-broken.pdf.
>
> For the correct result, see test-correct.pdf (add a space and any letter  
> - uncomment the end of line 19).
>
> Adobe Naskh is not publicly available. The four commented fonts are  
> publicly available and generate no tex errors.
>
> Best wishes
> Idris


-- 
Idris Samawi Hamid, Professor
Department of Philosophy
Colorado State University
Fort Collins, CO 80512