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spec: should octal escape sequences in string literals accept an "o" prefix? #30225

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josharian opened this issue Feb 14, 2019 · 4 comments
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spec: should octal escape sequences in string literals accept an "o" prefix? #30225

josharian opened this issue Feb 14, 2019 · 4 comments
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FrozenDueToAge NeedsDecision Feedback is required from experts, contributors, and/or the community before a change can be made. v2 A language change or incompatible library change
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Go1.13

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@josharian
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This is a minor follow-up to #19308; I've started a new issue since that one is long, and this is a corner case.

In the String literals section, the spec says:

The three-digit octal (\nnn) and two-digit hexadecimal (\xnn) escapes represent individual bytes of the resulting string [...] inside a string literal \377 and \xFF represent a single byte of value 0xFF=255

Given that we are moving towards using 0o for octal integers, and given that hexadecimal escaping in string literals begins \x, should string literals also accept a \o prefix for octal bytes?

I suspect that so few people use octal byte escape sequences in string literals that it's not worth changing for consistency, but I thought it worth making an explicit decision about.

cc @griesemer @rsc @ianlancetaylor
@josharian josharian added v2 A language change or incompatible library change NeedsDecision Feedback is required from experts, contributors, and/or the community before a change can be made. labels Feb 14, 2019
@josharian josharian added this to the Go1.13 milestone Feb 14, 2019
@robpike
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robpike commented Feb 14, 2019 •
edited

I can't remember even seeing an octal string escape in the wild. Everyone uses \x or \u. I don't think it's worthwhile. String literals are complicated enough already.

@griesemer
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Agreed. I don't think we should touch string and rune escapes.

@josharian
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Great. I'll call this decided; thanks.

@ianlancetaylor
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To the best of my knowledge and research ability the only languages that support a string literal octal escape of the form "\oDDD" are Perl (in the form \o{DDD}) and Haskell. Languages like Rust and Swift don't even support the form \DDD that we copied from C, and only support hex (Rust) and Unicode (Rust and Swift) escapes. So I don't see much reason to add "\oDDD" to Go.

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FrozenDueToAge NeedsDecision Feedback is required from experts, contributors, and/or the community before a change can be made. v2 A language change or incompatible library change
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