Numeric literal expressions and literal suffixes#1177

mattheww · 2022-03-06T17:30:18Z

This documents integer and floating-point literal expressions, and improves the docs for integer and floating-point literal tokens.

Covers some of #939, for integer and floating-point literals.

Covers the RFC 0879 part of #298, and some of the RFC 0463 part (ie, for numeric literals but not string literals).

The details of floating-point conversion deserve a more throrough description, but maybe that needs looking at together with the standard library docs.

I had a false-positive error from linkchecker; the last commit is a workaround for that, but I think the right thing would be an addition to LINKCHECK_EXCEPTIONS in linkcheck/main.rs.

… literal-expr.md

…ther than tokens.md

…r.md rather than tokens.md

…rmined For now, refer to the stdlib docs for the actual interpretation.

…terals

A LINKCHECK_EXCEPTIONS entry in linkchecker/main.rs seems to be the right way to do this, but that's not in this repository.

ehuss

Thanks for putting this together, it looks like a good improvement and step in the right direction. I had a few questions and a few nit-picks.

src/expressions/literal-expr.md

src/tokens.md

ehuss · 2022-03-21T03:19:29Z

src/tokens.md

+> &nbsp;&nbsp; IDENTIFIER_OR_KEYWORD <sub>_not matching INTEGER_SUFFIX or FLOAT_SUFFIX_</sub>
+>
+> NUMBER_PSEUDOLITERAL_SUFFIX_NO_E :\
+> &nbsp;&nbsp; NUMBER_PSEUDOLITERAL_SUFFIX <sub>_not beginning with `e` or `E`_</sub>


This "beginning with e" is a bit surprising to me. So strange!

src/tokens.md

mattheww · 2022-03-21T21:14:04Z

@ehuss I'll put your rewordings in. Would you prefer me to make additional commits, or amend the original commits with a force-push?

ehuss · 2022-03-22T00:43:59Z

I think adding a single commit with the updates would be fine.

The previous phrasing missed raw identifiers, raw string literals, and byte literals. Writing in terms of characters rather than tokens matches the implementation more closely.

src/expressions/literal-expr.md

Havvy

First off, I want to personally thank you for working on this page; this is a good chunk of content and it reads nicely. I'm not going to be nitpicky (I don't have the energy to do so and @ehuss is already doing so), but I do notice one glaring thing:

We no longer have prose about boolean, character, and string literals. We should have something, even if it's just section for them and the statements An x literal statement consists of a single [X_LITERAL] token. & This section is incomplete..

…ented

mattheww · 2022-03-23T20:15:10Z

@Havvy I've added placeholder sections for the other types of literal expression. Some of them will be very easy to fill in, but I suppose that doesn't belong in this PR.

(Do you have an opinion on the choice in #1167? I'm leaning towards the second option.)

ehuss

Looks good, thanks!

ehuss · 2022-03-31T22:53:37Z

@Havvy Are you OK with the changes?

Havvy · 2022-04-01T00:08:55Z

Yes. Quite pleased actually.

Update books ## nomicon 1 commits in 11f1165e8a2f5840467e748c8108dc53c948ee9a..c7d8467ca9158da58ef295ae65dbf00a308752d9 2022-03-19 16:02:00 -0400 to 2022-04-06 14:26:54 +0900 - Change "writers" to "readers" for Deref. (rust-lang/nomicon#346) ## reference 7 commits in c97d14fa6fed0baa9255432b8a93cb70614f80e3..b5f6c2362baf932db9440fbfcb509b309237ee85 2022-03-19 18:18:10 -0700 to 2022-04-10 19:19:51 -0700 - Fix typo: `?` should be inside `<sup>` tags (rust-lang/reference#1190) - Update aarch64 to use neon as fp (rust-lang/reference#1184) - Boolean literal expressions (rust-lang/reference#1189) - Document that unary negation of a signed integer literal cannot cause an overflow error (rust-lang/reference#1188) - Document compatibility between declarative and procedural macro tokens (rust-lang/reference#1169) - Document native library modifier syntax and the `whole-archive` modifier specifically (rust-lang/reference#1170) - Numeric literal expressions and literal suffixes (rust-lang/reference#1177) ## book 8 commits in ea90bbaf53ba64ef4e2da9ac2352b298aec6bec8..765318b844569a642ceef7bf1adab9639cbf6af3 2022-03-28 21:59:34 -0400 to 2022-04-12 21:14:47 -0400 - Propagate nostarch edits to src - Propagate updated test example code to nostarch snapshot - Edits to nostarch edits - edits from nostarch - Fix error message for the example code - update ch13-02 to reflect changes in rust-lang/book#2797 - Update to 1.59 - Edits to chapter 2 after tech review ## rust-by-example 4 commits in ec954f35eedf592cd173b21c05a7f80a65b61d8a..c2a98d9fc5d29c481d42052fbeccfde15ed03116 2022-03-22 11:09:06 -0300 to 2022-04-08 06:44:18 -0300 - Code highlight a variable (rust-lang/rust-by-example#1530) - Add a comment to note that warnings may not be shown in a browser in the Variable Bindings section (rust-lang/rust-by-example#1529) - Make all new types have UpperCamelCase names in code example in the Aliasing section (rust-lang/rust-by-example#1528) - Replace `C` with C/C++ (rust-lang/rust-by-example#1527) ## rustc-dev-guide 6 commits in 155126b..eeb5a83 2022-03-22 14:34:21 +0100 to 2022-04-11 23:29:48 +0900 - method-lookup.md improvements (rust-lang/rustc-dev-guide#1296) - Consolidate crates.io convention section (rust-lang/rustc-dev-guide#1326) - Update examples with 1.61.0-nightly (latest version) (rust-lang/rustc-dev-guide#1330) - r-a: Use `python3 x.py` instead of `./x.py` (rust-lang/rustc-dev-guide#1335) - Update miri.md: correct a minor typo (rust-lang/rustc-dev-guide#1334) - Add example how lints can be feature gated

mattheww added 17 commits March 5, 2022 22:29

tokens.md: move the link reference definitions to the end of the file

34e7e5f

Move the general description of literal expressions from tokens.md to…

e06fea0

… literal-expr.md

Describe the effect of integer literal suffixes in literal-expr.md ra…

9b32e40

…ther than tokens.md

Describe the effect of floating-point literal suffixes in literal-exp…

8fbbbda

…r.md rather than tokens.md

Document how the value of an integer literal expression is determined

d478e54

Say that integer literals out of the u128 range are a parse-time error

938011b

Literal expressions: add a Note describing the overflowing_literals lint

9495744

Document how the value of a floating-point literal expression is dete…

72a554a

…rmined For now, refer to the stdlib docs for the actual interpretation.

Literal expressions: add a Note on infinite and NaN floating-point li…

c8b9a20

…terals

Notes about negated literals

1913a4f

Say that out-of-range suffixed integer literals are valid lexer tokens

46d4a27

Make the FLOAT_LITERAL rule mention keywords as well as identifiers

5f81f6a

Add the 5f32 case to the text description of floating-point literals

71fd6e3

Add some examples of possibly confusing hexadecimal literals

e2015cc

Add a Lexer rules block for number literals with arbitrary suffixes

6a379ac

Document reserved forms similar to number literals

6e19792

tokens.md: add two zero-width spaces to placate linkchecker

e5ef69a

A LINKCHECK_EXCEPTIONS entry in linkchecker/main.rs seems to be the right way to do this, but that's not in this repository.

ehuss reviewed Mar 21, 2022

View reviewed changes

Cover two missing cases of number pseudoliterals

8aa8b9a

mattheww added 4 commits March 22, 2022 22:17

Make the FLOAT_LITERAL rule about final . more accurate

7baad0a

The previous phrasing missed raw identifiers, raw string literals, and byte literals. Writing in terms of characters rather than tokens matches the implementation more closely.

Literal expressions: text improvements from ehuss

9704aad

tokens.md: add missing superscript markup

56105c2

Number pseudoliterals and reserved forms: text improvements from ehuss

d1f3e7f

Havvy reviewed Mar 23, 2022

View reviewed changes

src/expressions/literal-expr.md Outdated Show resolved Hide resolved

Havvy suggested changes Mar 23, 2022

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mattheww added 2 commits March 23, 2022 19:55

Literal expressions: use a sublist when describing choice of radix

0c4554f

Literal expressions: add placeholder sections for types not yet docum…

2c78399

…ented

ehuss approved these changes Mar 31, 2022

View reviewed changes

Havvy approved these changes Apr 1, 2022

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ehuss merged commit b85bbf4 into rust-lang:master Apr 1, 2022

ehuss mentioned this pull request Apr 14, 2022

Update books rust-lang/rust#96032

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mattheww mentioned this pull request Apr 17, 2022

Minimum signed integer literal #779

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mattheww commented Mar 6, 2022

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