Correct code point format in Base/Char/show function

[srutzky]

Two minor changes (both on line 307) to conform to the Unicode Standard.

Unicode code points currently display with:

1. Lowercase letters, a - f, when present
2. A leading 0 for 5-digit code point values (i.e. 10000 - 9ffff)

However, the Unicode Standard specifies that when using the "U+" notation, you should use:

1. Uppercase letters
2. Leading zeros only when the code point would have fewer than four digits (i.e. 0000 - 0FFF)

For reference, the Unicode Standard (two versions to show consistency over time)

• (Version 12.1, 2019) Appendix A: Notational Conventions ⇒ Code Points
• (Version 4.0.0, 2003) Preface: Notational Conventions ⇒ Code Points

states:

In running text, an individual Unicode code point is expressed as U+n, where n is four to six hexadecimal digits, using the digits 0–9 and uppercase letters A–F (for 10 through 15, respectively). Leading zeros are omitted, unless the code point would have fewer than four
hexadecimal digits—for example, U+0001, U+0012, U+0123, U+1234, U+12345, U+102345.

[stevengj]

Looks good to me, but could use a test.

[srutzky]

Hi @stevengj . Fair enough, though I am not sure how formal of a test you are requesting. I do not currently have the ability to compile Julia. However, I did verify the syntax using the Julia command-line (i.e. julia.exe) as shown below. Does this suffice for a trivial change such as this one?

Old Syntax

julia> u=0x1b3
0x01b3

julia> string(u, base = 16, pad = u ≤ 0xffff ? 4 : 6)
"01b3"

julia> u=0x1b3d
0x1b3d

julia> string(u, base = 16, pad = u ≤ 0xffff ? 4 : 6)
"1b3d"

julia> u=0x1b3d5
0x0001b3d5

julia> string(u, base = 16, pad = u ≤ 0xffff ? 4 : 6)
"01b3d5"

julia> u=0x1b3d5f
0x001b3d5f

julia> string(u, base = 16, pad = u ≤ 0xffff ? 4 : 6)
"1b3d5f"

New Syntax

julia> u=0x1b3
0x01b3

julia> uppercase(string(u, base = 16, pad = 4))
"01B3"

julia> u=0x1b3d
0x1b3d

julia> uppercase(string(u, base = 16, pad = 4))
"1B3D"

julia> u=0x1b3d5
0x0001b3d5

julia> uppercase(string(u, base = 16, pad = 4))
"1B3D5"

julia> u=0x1b3d5f
0x001b3d5f

julia> uppercase(string(u, base = 16, pad = 4))
"1B3D5F"

[stevengj]

Basically we would want something like

@test repr("text/plain", 'α') == "'α': Unicode U+03B1 (category Ll: Letter, lowercase)"
@test repr("text/plain", '🐨') == "'🐨': Unicode U+1F428 (category So: Symbol, other)"

in test/char.jl.

You can just edit test/char.jl to add these tests to the PR, and then the CI scripts will run them automatically — no need to compile Julia locally.

[srutzky]

Hi @stevengj . Test file has been updated and added to this PR as requested. Please let me know if there is anything I need to change regarding the tests. I just added a new testset to the end of that file.

[stevengj]

Windows failure is #33311. Linux failure is #33312. Both seem unrelated.

[StefanKarpinski]

This could use a NEWS entry since it's an observable behavior change.

[stevengj]

Fixed in 64d8ca4