Clarify that 0 is a valid multiple of a type's alignment #1260
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The reference currently states that "[t]he size of a value is always a multiple of its alignment." This might be taken to imply that a type's size is greater than or equal to its alignment. This commit clarifies that 0 is a valid multiple; zero-sized types have 0 size and nonzero alignment.
ehuss
approved these changes
Sep 10, 2022
There was a problem hiding this comment.
Thanks! Yea, it does seem like 0 is considered a factor. I've always felt this paragraph is a bit awkward in how it uses array layout to define size.
I'm going to go ahead and merge even though I'm not 100% confident in the wording here. If someone wants to rework it to be clearer, feel free to follow up.
matthiaskrgr
added a commit
to matthiaskrgr/rust
that referenced
this pull request
Sep 21, 2022
Update books ## nomicon 1 commits in d880e6ac2acf133dce640da24b9fb692844f02d4..f53bfa056929217870a5d2df1366d2e7ba35096d 2022-08-24 12:42:34 -0700 to 2022-09-05 07:19:02 -0700 - Small typo (rust-lang/nomicon#379) ## reference 9 commits in f62e93c28323ed9637d0a205a0c256498674a509..a7cdac33ca7356ad49d5c2b5e2c5010889b33eee 2022-08-28 10:01:28 -0700 to 2022-09-19 17:39:58 -0700 - Clarify wording for references. (rust-lang/reference#1223) - Update Unicode reference to match rustc implementation (rust-lang/reference#1271) - Add documentation for raw-dylib and link_ordinal (rust-lang/reference#1244) - Specify guarantees for repr(rust) structs (rust-lang/reference#1152) - Classify AsyncBlockExpression as ExpressionWithoutBlock (rust-lang/reference#1268) - Update closure-expr.md (rust-lang/reference#1269) - Clarify that 0 is a valid multiple of a type's alignment (rust-lang/reference#1260) - Remove `ne` from derive example (rust-lang/reference#1264) - Clarify reference on async blocks (rust-lang/reference#1262) ## book 6 commits in 0a5421ceb238357b3634fb75234eba4d1dad643c..f1e5ad844d0c61738006cdef26227beeb136948e 2022-08-28 19:51:04 -0400 to 2022-09-19 09:48:21 -0400 - Fix punctuation in ch05-02 - Ownership move chapter link fix - Wrong listing number - Reword text around box - `Box<T>` instead of "box" - Update Clippy output in Appendix D ## rust-by-example 2 commits in 03301f8ae55fa6f20f7ea152a517598e6db2cdb7..767a6bd9727a596d7cfdbaeee475e65b2670ea3a 2022-08-14 08:51:44 -0300 to 2022-09-14 09:17:18 -0300 - struct_visibility.md: Remove unneeded '#[allow(dead_code)]' (rust-lang/rust-by-example#1609) - Fix assorted typos (rust-lang/rust-by-example#1601) ## rustc-dev-guide 15 commits in 04892c1..f587d6e 2022-08-29 20:07:51 +0200 to 2022-09-20 07:43:59 +0900 - Update stability guide to use CURRENT_RUSTC_VERSION (rust-lang/rustc-dev-guide#1468) - Add a note about building `rust-analyzer-proc-macro-srv` (rust-lang/rustc-dev-guide#1467) - Link from "implementing to new features" to mcp.md (rust-lang/rustc-dev-guide#1465) - remove stray ** - Explain the new valtree system for type level constants. (rust-lang/rustc-dev-guide#1097) - fix typos and formatting - Say "bootstrap" instead of "rustbuild"; the latter is not explained anywhere and is not much more clear. - Rewrite the section on passing flags to subcommands - Remove the diagram of all outputs generated by x.py - "symbol names" => ABI - Add symbol-addition to the how-to for new features (rust-lang/rustc-dev-guide#1457) - Fix typo (rust-lang/rustc-dev-guide#1459) - Document multipart_suggestion derive on SessionSubdiagnostic - Add reference for updating Windows PATH and fix typo - Update for removal of RLS (rust-lang/rustc-dev-guide#1450) ## embedded-book 1 commits in befe6840874311635c417cf731377f07234ee373..4ce51cb7441a6f02b5bf9b07b2eb755c21ab7954 2022-07-25 07:51:14 +0000 to 2022-09-15 08:53:09 +0000 - Create CITATION.bib (as per rust-embedded/book#327) (rust-embedded/book#329)
JohnTitor
added a commit
to JohnTitor/rust
that referenced
this pull request
Sep 22, 2022
Update books ## nomicon 1 commits in d880e6ac2acf133dce640da24b9fb692844f02d4..f53bfa056929217870a5d2df1366d2e7ba35096d 2022-08-24 12:42:34 -0700 to 2022-09-05 07:19:02 -0700 - Small typo (rust-lang/nomicon#379) ## reference 9 commits in f62e93c28323ed9637d0a205a0c256498674a509..a7cdac33ca7356ad49d5c2b5e2c5010889b33eee 2022-08-28 10:01:28 -0700 to 2022-09-19 17:39:58 -0700 - Clarify wording for references. (rust-lang/reference#1223) - Update Unicode reference to match rustc implementation (rust-lang/reference#1271) - Add documentation for raw-dylib and link_ordinal (rust-lang/reference#1244) - Specify guarantees for repr(rust) structs (rust-lang/reference#1152) - Classify AsyncBlockExpression as ExpressionWithoutBlock (rust-lang/reference#1268) - Update closure-expr.md (rust-lang/reference#1269) - Clarify that 0 is a valid multiple of a type's alignment (rust-lang/reference#1260) - Remove `ne` from derive example (rust-lang/reference#1264) - Clarify reference on async blocks (rust-lang/reference#1262) ## book 6 commits in 0a5421ceb238357b3634fb75234eba4d1dad643c..f1e5ad844d0c61738006cdef26227beeb136948e 2022-08-28 19:51:04 -0400 to 2022-09-19 09:48:21 -0400 - Fix punctuation in ch05-02 - Ownership move chapter link fix - Wrong listing number - Reword text around box - `Box<T>` instead of "box" - Update Clippy output in Appendix D ## rust-by-example 2 commits in 03301f8ae55fa6f20f7ea152a517598e6db2cdb7..767a6bd9727a596d7cfdbaeee475e65b2670ea3a 2022-08-14 08:51:44 -0300 to 2022-09-14 09:17:18 -0300 - struct_visibility.md: Remove unneeded '#[allow(dead_code)]' (rust-lang/rust-by-example#1609) - Fix assorted typos (rust-lang/rust-by-example#1601) ## rustc-dev-guide 15 commits in 04892c1..f587d6e 2022-08-29 20:07:51 +0200 to 2022-09-20 07:43:59 +0900 - Update stability guide to use CURRENT_RUSTC_VERSION (rust-lang/rustc-dev-guide#1468) - Add a note about building `rust-analyzer-proc-macro-srv` (rust-lang/rustc-dev-guide#1467) - Link from "implementing to new features" to mcp.md (rust-lang/rustc-dev-guide#1465) - remove stray ** - Explain the new valtree system for type level constants. (rust-lang/rustc-dev-guide#1097) - fix typos and formatting - Say "bootstrap" instead of "rustbuild"; the latter is not explained anywhere and is not much more clear. - Rewrite the section on passing flags to subcommands - Remove the diagram of all outputs generated by x.py - "symbol names" => ABI - Add symbol-addition to the how-to for new features (rust-lang/rustc-dev-guide#1457) - Fix typo (rust-lang/rustc-dev-guide#1459) - Document multipart_suggestion derive on SessionSubdiagnostic - Add reference for updating Windows PATH and fix typo - Update for removal of RLS (rust-lang/rustc-dev-guide#1450) ## embedded-book 1 commits in befe6840874311635c417cf731377f07234ee373..4ce51cb7441a6f02b5bf9b07b2eb755c21ab7954 2022-07-25 07:51:14 +0000 to 2022-09-15 08:53:09 +0000 - Create CITATION.bib (as per rust-embedded/book#327) (rust-embedded/book#329)
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The reference currently states that "[t]he size of a value is always a multiple of its alignment." This might be taken to imply that a type's size is greater than or equal to its alignment. This commit clarifies that 0 is a valid multiple; zero-sized types have 0 size and nonzero alignment.