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Name starting with non-ascii uppercase letter is not treated as constant #12791

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kolesar-andras opened this issue Nov 28, 2022 · 2 comments · May be fixed by #12792 or #15148
Open

Name starting with non-ascii uppercase letter is not treated as constant #12791

kolesar-andras opened this issue Nov 28, 2022 · 2 comments · May be fixed by #12792 or #15148
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kind:bug A bug in the code. Does not apply to documentation, specs, etc. topic:compiler:parser

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@kolesar-andras
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The following code does not compile:

class ÁrvíztűrőTükörfúrógép
end

Error: expecting token 'CONST', not 'ÁrvíztűrőTükörfúrógép'

Some corner cases to narrow the problem:

  • Á fails
  • A works
  • Aőű works
  • AőűŐű also works

When a name starts with non-ascii uppercase letter (for example Á) it is currently not treated as constant.

This bevaviour also causes a bug:

Á = 1
Á = 2 # no error (Á is treated as a variable, not constant)

A = 1
A = 2 # Error: already initialized constant A

Running on Ubuntu 21.10:

$ crystal -v
Crystal 1.6.2 [879691b2e] (2022-11-03)

LLVM: 13.0.1
Default target: x86_64-unknown-linux-gnu
@kolesar-andras kolesar-andras added the kind:bug A bug in the code. Does not apply to documentation, specs, etc. label Nov 28, 2022
kolesar-andras added a commit to kolesar-andras/crystal that referenced this issue Nov 28, 2022
@kolesar-andras
Fix constants starting with non-ascii uppercase letter
c5d3e6c 
treat names starting with any uppercase letter as constant
not only ascii uppercase letters (A-Z)
for example Á (Latin Capital Letter A with Acute)

Fixes crystal-lang#12791
@kolesar-andras kolesar-andras linked a pull request Nov 28, 2022 that will close this issue
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@straight-shoota
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straight-shoota commented Nov 28, 2022 •
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This might have been discussed somewhere before, but I'm not sure.

Uppercase first-character indicates a constant and it's a very relevant distinction from a lowercase variable. That means the two cases need to be easily discernible. There might be some trouble with that when following the Unicode character classes.

That being said, I think it's generally a good idea to allow using non-ASCII characters in identifiers the same way as ASCII characters.

The above example with class ÁrvíztűrőTükörfúrógép works in Ruby, btw.

@HertzDevil
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The same can also be said about titlecase characters, i.e. Chars that belong to the Unicode Lt (letter titlecase) general category: Dž Lj Nj Dz ᾈ ᾉ ᾊ ᾋ ᾌ ᾍ ᾎ ᾏ ᾘ ᾙ ᾚ ᾛ ᾜ ᾝ ᾞ ᾟ ᾨ ᾩ ᾪ ᾫ ᾬ ᾭ ᾮ ᾯ ᾼ ῌ ῼ

Ruby also treats identifiers starting with titlecase characters as constants rather than variables.

nanobowers added a commit to nanobowers/crystal that referenced this issue Nov 2, 2024
@nanobowers
Modified parser to allow constants to start with non-ascii uppercase …
3e7fcc7 
…and titlecase.

Fixes crystal-lang#12791
nanobowers added a commit to nanobowers/crystal that referenced this issue Nov 2, 2024
@nanobowers
Modified parser to allow constants to start with non-ascii uppercase …
81b6aed 
…and titlecase.

Fixes crystal-lang#12791
@nanobowers nanobowers linked a pull request Nov 2, 2024 that will close this issue
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