Add float conversions to and from bytes #58756

tbu- · 2019-02-26T15:49:48Z

Use the same API as for integers.

Fixes #57492.

rust-highfive · 2019-02-26T15:49:54Z

r? @aidanhs

(rust_highfive has picked a reviewer for you, use r? to override)

tbu- · 2019-02-26T15:50:07Z

Will add docs if the general approach is deemed to be okay.

rust-highfive · 2019-02-26T16:12:42Z

The job x86_64-gnu-llvm-6.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

travis_time:end:1570503c:start=1551196401450103822,finish=1551196405862117709,duration=4412013887
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
Setting environment variables from .travis.yml
$ export IMAGE=x86_64-gnu-llvm-6.0
---
[00:09:52]    Compiling rustc_lsan v0.0.0 (/checkout/src/librustc_lsan)
[00:09:55] error[E0308]: mismatched types
[00:09:55]    --> src/libcore/num/f64.rs:516:20
[00:09:55]     |
[00:09:55] 516 |         swap_if_le(Self::from_ne_bytes(bytes))
[00:09:55]     |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected array of 8 elements, found f64
[00:09:55]     |
[00:09:55]     = note: expected type `[u8; 8]`
[00:09:55]                found type `f64`
[00:09:55] error[E0308]: mismatched types
[00:09:55]    --> src/libcore/num/f64.rs:516:9
[00:09:55]     |
[00:09:55]     |
[00:09:55] 515 |     pub const fn from_be_bytes(bytes: [u8; 8]) -> Self {
[00:09:55]     |                                                   ---- expected `f64` because of return type
[00:09:55] 516 |         swap_if_le(Self::from_ne_bytes(bytes))
[00:09:55]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected f64, found array of 8 elements
[00:09:55]     = note: expected type `f64`
[00:09:55]     = note: expected type `f64`
[00:09:55]                found type `[u8; 8]`
[00:09:55] error[E0308]: mismatched types
[00:09:55]    --> src/libcore/num/f64.rs:523:20
[00:09:55]     |
[00:09:55]     |
[00:09:55] 523 |         swap_if_be(Self::from_ne_bytes(bytes))
[00:09:55]     |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected array of 8 elements, found f64
[00:09:55]     |
[00:09:55]     = note: expected type `[u8; 8]`
[00:09:55]                found type `f64`
[00:09:55] error[E0308]: mismatched types
[00:09:55]    --> src/libcore/num/f64.rs:523:9
[00:09:55]     |
[00:09:55]     |
[00:09:55] 522 |     pub const fn from_le_bytes(bytes: [u8; 8]) -> Self {
[00:09:55]     |                                                   ---- expected `f64` because of return type
[00:09:55] 523 |         swap_if_be(Self::from_ne_bytes(bytes))
[00:09:55]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected f64, found array of 8 elements
[00:09:55]     = note: expected type `f64`
[00:09:55]     = note: expected type `f64`
[00:09:55]                found type `[u8; 8]`
[00:10:01] error: aborting due to 4 previous errors
[00:10:01] 
[00:10:01] For more information about this error, try `rustc --explain E0308`.
[00:10:01] error: Could not compile `core`.
---
travis_time:end:046ffba8:start=1551197019631286950,finish=1551197019636406152,duration=5119202
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:00982b0c
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:0a3e86b8
travis_time:start:0a3e86b8
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:0e7167ce
$ dmesg | grep -i kill

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

src/libcore/num/f32.rs

Dylan-DPC-zz · 2019-03-18T10:32:27Z

ping from triage @tbu- waiting for your updates on the PR in reply to the review above

Use the same API as for integers. Fixes rust-lang#57492.

rust-highfive · 2019-03-18T11:59:32Z

The job x86_64-gnu-llvm-6.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

travis_time:end:140483b4:start=1552910074182578083,finish=1552910075151753730,duration=969175647
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
$ export GCP_CACHE_BUCKET=rust-lang-ci-cache
Setting environment variables from .travis.yml
---
[00:04:28]    Compiling rustc_asan v0.0.0 (/checkout/src/librustc_asan)
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f32.rs:536:5
[00:04:42]     |
[00:04:42] 536 |     pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
[00:04:42]     |
[00:04:42]     = note: `-D missing-docs` implied by `-D warnings`
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f32.rs:543:5
[00:04:42]     |
[00:04:42] 543 |     pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f32.rs:550:5
[00:04:42]     |
[00:04:42]     |
[00:04:42] 550 |     pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f64.rs:494:5
[00:04:42]     |
[00:04:42]     |
[00:04:42] 494 |     pub const fn to_be_bytes(self) -> [u8; 8] {
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f64.rs:501:5
[00:04:42]     |
[00:04:42]     |
[00:04:42] 501 |     pub const fn to_le_bytes(self) -> [u8; 8] {
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f64.rs:508:5
[00:04:42]     |
[00:04:42]     |
[00:04:42] 508 |     pub const fn to_ne_bytes(self) -> [u8; 8] {
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f64.rs:515:5
[00:04:42]     |
[00:04:42]     |
[00:04:42] 515 |     pub const fn from_be_bytes(bytes: [u8; 8]) -> Self {
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f64.rs:522:5
[00:04:42]     |
[00:04:42]     |
[00:04:42] 522 |     pub const fn from_le_bytes(bytes: [u8; 8]) -> Self {
[00:04:42] 
[00:04:42] error: missing documentation for a method
[00:04:42]    --> src/libcore/num/f64.rs:529:5
[00:04:42]     |
[00:04:42]     |
[00:04:42] 529 |     pub const fn from_ne_bytes(bytes: [u8; 8]) -> Self {
[00:04:42] 
[00:04:43] error: aborting due to 9 previous errors
[00:04:43] 
[00:04:43] error: Could not compile `core`.
---
travis_time:end:02a6fb47:start=1552910369789953950,finish=1552910369795876935,duration=5922985
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:285fb487
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:2abc0ac8
travis_time:start:2abc0ac8
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:26f79a02
$ dmesg | grep -i kill

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

tbu- · 2019-03-18T12:12:20Z

I'm not really sure what to put into the examples. Does that work?

Dylan-DPC-zz · 2019-03-25T13:37:56Z

ping from triage @tbu- @aidanhs any updates on this?

tbu- · 2019-03-25T22:54:13Z

I was wondering whether the examples are fine or what I should extend them with.

Centril · 2019-03-30T13:00:58Z

Ping from triage...

r? @scottmcm
cc @tbu-

scottmcm · 2019-04-02T04:24:53Z

The code here seems fine, but since it's a new API I think it should have someone from @rust-lang/libs take a look at the APIs and comment if they're interested before going in.

(Not a full FCP, since they're just unstable, but I'm not up-to-date on what they're looking for in new stuff.)

Also, @tbu-, you have travis failures: error: missing documentation for a method

SimonSapin · 2019-04-02T06:58:57Z

I personally feel that the need for these APIs is less pressing than the integer ones, because this operation can already be achieved without unsafe code. (Without transmute, in particular.)

But I’m not entirely opposed either. I could see the argument that this more discoverable, it might not be obvious that e.g. u32::from_be_bytes and f32::from_bits can be combined in this way.

Let’s see what other @rust-lang/libs members think.

alexcrichton · 2019-04-02T15:47:28Z

I'd personally be in favor of being consistent across all the primitive types, so I'd be ok merging and eventually stabilizing this. I don't feel too strongly though and agree @SimonSapin that the pressure isn't so high as there's already methods of doing this, but I'd just fall a little bit on the other side of the fence!

alexcrichton · 2019-05-01T17:53:33Z

@SimonSapin this was pinged back to the libs team recently, do you feel that this shouldn't land as unstable to start off with? It looks like there aren't a ton of other opinions about htese APIs.

SimonSapin · 2019-05-01T19:19:35Z

Alright, let’s land this. @tbu-, could you make a few changes?

Change the tracking issue number to Tracking issue for floats ↔ bytes conversions #60446
Remove rustc_const_unstable attributes as they’re redundant with unstable attributes. When doing FCP to stabilize we’ll do so as const fn, no need for a separate FCP just for constness.
Add some documentation to from_* methods and f64 methods.

Centril · 2019-05-01T19:41:06Z

When doing FCP to stabilize we’ll do so as const fn, no need for a separate FCP just for constness.

I would suggest keeping rustc_const_unstable as it is highly unlikely that you'll get to stabilize the constness concurrently with the usual stabilization. The function to_bits isn't const fn (and won't be soon) and moreover we do not generally allow floating point related logic in const fn because of differences in behavior between runtime and compile time function execution (if there provably cannot be differences in this instance then it may be workable but we need a larger discussion that should not block the initial stabilization).

jonas-schievink · 2019-06-10T12:41:25Z

Ping from triage @tbu-, this still needs a few changes before it can be merged.

jonas-schievink · 2019-06-10T12:43:02Z

if there provably cannot be differences in this instance then it may be workable

AFAIK, NaN payloads are generally processor-specific, and they can be observed and manipulated using these functions. Perhaps this should not be a const fn at all then?

Dylan-DPC-zz · 2019-06-24T16:05:02Z

ping from triage @tbu- any updates?

scottmcm · 2019-07-02T05:43:32Z

@tbu- I'm going to close this for now to keep the backlog clean. Please do re-open it if you get the chance to address the comments in #58756 (comment).

tesuji · 2019-07-04T09:52:46Z

I reworked this in #62366 .

@SimonSapin

Add float conversions to and from bytes Rework of #58756. Address #58756 (comment). Fixes #57492. r? @SimonSapin

rust-highfive assigned aidanhs Feb 26, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Feb 26, 2019

scottmcm reviewed Feb 27, 2019

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src/libcore/num/f32.rs Outdated Show resolved Hide resolved

scottmcm added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Feb 27, 2019

Dylan-DPC-zz added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 18, 2019

Add float conversions to and from bytes

f39230e

Use the same API as for integers. Fixes rust-lang#57492.

tbu- force-pushed the pr_floatfromtobytes branch from ac81d82 to f39230e Compare March 18, 2019 11:53

rust-highfive assigned scottmcm and unassigned aidanhs Mar 30, 2019

Dylan-DPC-zz added S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 29, 2019

SimonSapin mentioned this pull request May 1, 2019

Tracking issue for floats ↔ bytes conversions #60446

Closed

SimonSapin added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). labels May 1, 2019

jonas-schievink closed this Jul 2, 2019

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tesuji mentioned this pull request Jul 4, 2019

Add float conversions to and from bytes #62366

Merged

bors added a commit that referenced this pull request Jul 8, 2019

Auto merge of #62366 - lzutao:feature/float-from-to-bytes, r=SimonSapin

10840b8

Add float conversions to and from bytes Rework of #58756. Address #58756 (comment). Fixes #57492. r? @SimonSapin

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tbu- commented Feb 26, 2019

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Add float conversions to and from bytes #58756

Add float conversions to and from bytes #58756

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