[ruby-core:112901] [Ruby master Bug#19485] Unexpected behavior in squiggly heredocs

Issue #19485 has been updated by jemmai (Jemma Issroff).


sawa (Tsuyoshi Sawada) wrote in #note-3:

> For the purpose of measuring an indentation, a horizontal tab is regarded as a sequence of one to eight spaces such that the column position corresponding to its end is a multiple of eight. The amount to be removed is counted in terms of the number of spaces. If the boundary appears in the middle of a tab, that tab is not removed.

This documentation is very clear to me, and explains both cases I've mentioned in a way that is easy to understand.


----------------------------------------
Bug #19485: Unexpected behavior in squiggly heredocs
https://bugs.ruby-lang.org/issues/19485#change-102419

* Author: jemmai (Jemma Issroff)
* Status: Assigned
* Priority: Normal
* Assignee: core
* ruby -v: 3.2.1
* Backport: 2.7: UNKNOWN, 3.0: REQUIRED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
Based on [the squiggly heredoc documentation](https://ruby-doc.org/3.2.1/syntax/literals_rdoc.html), I found the following to be unexpected behavior. Explicitly, the documentation specifies, "The indentation of the least-indented line will be removed from each line of the content." 

After running:

```ruby
File.write("test.rb", "p <<~EOF\n\ta\n  b\nEOF\n")
```

and then `ruby test.rb`, I get the following output:

```
"\ta\nb\n"
```


The least-indented line above is `  b`, however, no leading whitespace is removed from the line containing `\ta`. 

For another example:

```ruby
File.write("test.rb", "p <<~EOF\n\tA\n  \tB\nEOF\n")
```

`ruby test.rb` gives:

```
"A\nB\n"
```

In this case, the `\t` was removed from the line containing `A`, but more whitespace than that (`  \t`) was removed from the line containing `B`.

After seeing the first example, I assumed that the documentation was out of date, and that I should fix it to read that `\t` would never be converted into space characters in order to remove leading whitespace. But after the second example, it seems like this is a bug in removing leading whitespace.

Can someone please explain what the rules should be on squiggly heredocs? I can implement a fix to adhere to the rules, or can update the documentation, I am just unsure of what the rules should be because the above two examples reflect unexpected behavior in two distinct ways.



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