demo of a github markdown rendering bug

badtabs.md

this is a demonstration of a bug in github's markdown rendering with tabs.. in code blocks nested under bullets, lines are rendered with an extra leading space character..

bullet list

• ❌ yukon

   alpha
   	alpha
   		alpha
   	alpha
   alpha
  

  • ❌ british columbia

     bravo
     	bravo
     		bravo
     	bravo
     bravo
    

number list

1. ✅ washington

   charlie
   	charlie
   		charlie
   	charlie
   charlie
   

   1. ✅ oregon

      delta
      	delta
      		delta
      	delta
      delta
      

hybrid number/bullet

1. ✅ baja california

   echo
   	echo
   		echo
   	echo
   echo
   

   • ❌ sonora

      foxtrot
      	foxtrot
      		foxtrot
      	foxtrot
      foxtrot
     

see this image of how my browser (firefox) is rendering this markdown:

i've highlighted (1) the good rendering of the numbered code block, vs (2) the bad rendering of the bulleted code block with the unwanted leading space

observe that this problem does not occur with the same raw text input at https://markdownlivepreview.com/

⚠️ important — this is not just merely an aesthetic problem — when you copy-paste the code, the leading spaces are actually injected into the resulting payload.

said differently, github is actually mangling the code, which will cause syntax errors in some languages.

the code blocks aren't just aesthetically wrong — they are functionally broken.

Great visual.

I don't get it

@iwoodroroo

i'll try to explain this more clearly:

if you are using tabs for indentation in a markdown github readme (which is nice because, with tabs, the indents are now displayed in accordance with the user's own preferences) — the problem is that there is a bug on github, where the text in some codeblocks is actually mangled — unwanted spacebar characters are inserted into the codeblock where none exist in the markdown source — this will cause confusing failures when somebody copy-and-pastes code snippets, because some programming languages require strictly correct indentation.

for more context, see this community discussion, and this one too.