impl TryFrom<{integer}> for NonZero{integer}#68825

jyn514 · 2020-02-04T14:48:24Z

I expected this to already exist and was surprised when it wasn't.

n.b. I don't think the UI tests are quite right, I can mess with them later today.

rust-highfive · 2020-02-04T14:48:35Z

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rust-highfive · 2020-02-04T15:52:41Z

The job x86_64-gnu-llvm-7 of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

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2020-02-04T14:48:57.9515384Z ========================== Starting Command Output ===========================
2020-02-04T14:48:57.9516521Z [command]/bin/bash --noprofile --norc /home/vsts/work/_temp/49b44902-07e5-4696-807e-330a350d6ba9.sh
2020-02-04T14:48:57.9516549Z 
2020-02-04T14:48:57.9518646Z ##[section]Finishing: Disable git automatic line ending conversion
2020-02-04T14:48:57.9523450Z ##[section]Starting: Checkout rust-lang/rust@refs/pull/68825/merge to s
2020-02-04T14:48:57.9524952Z Task         : Get sources
2020-02-04T14:48:57.9524980Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.
2020-02-04T14:48:57.9525022Z Version      : 1.0.0
2020-02-04T14:48:57.9525049Z Author       : Microsoft
---
2020-02-04T14:48:59.7636292Z ##[command]git remote add origin https://github.com/rust-lang/rust
2020-02-04T14:48:59.7646859Z ##[command]git config gc.auto 0
2020-02-04T14:48:59.7648699Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2020-02-04T14:48:59.7650091Z ##[command]git config --get-all http.proxy
2020-02-04T14:48:59.7655044Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/68825/merge:refs/remotes/pull/68825/merge
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---
2020-02-04T15:52:34.8245151Z 
2020-02-04T15:52:34.8245554Z error[E0689]: can't call method `try_into` on ambiguous numeric type `{integer}`
2020-02-04T15:52:34.8245906Z   --> $DIR/numeric-cast-3.rs:5:38
2020-02-04T15:52:34.8246086Z    |
2020-02-04T15:52:34.8246227Z LL |     #[should_panic] let b: usize = 0.try_into().unwrap();
2020-02-04T15:52:34.8246661Z    |
2020-02-04T15:52:34.8247053Z help: you must specify a concrete type for this numeric value, like `i32`
2020-02-04T15:52:34.8247123Z    |
2020-02-04T15:52:34.8247123Z    |
2020-02-04T15:52:34.8247169Z LL |     #[should_panic] let b: usize = 0_i32.try_into().unwrap();
2020-02-04T15:52:34.8247268Z 
2020-02-04T15:52:34.8247309Z error: aborting due to 2 previous errors
2020-02-04T15:52:34.8247336Z 
2020-02-04T15:52:34.8247856Z For more information about this error, try `rustc --explain E0689`.
2020-02-04T15:52:34.8247856Z For more information about this error, try `rustc --explain E0689`.
2020-02-04T15:52:34.8247891Z 
2020-02-04T15:52:34.8247914Z 
2020-02-04T15:52:34.8247936Z 
2020-02-04T15:52:34.8247993Z The actual stderr differed from the expected stderr.
2020-02-04T15:52:34.8248282Z Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/numeric/numeric-cast-3/numeric-cast-3.stderr
2020-02-04T15:52:34.8248510Z To update references, rerun the tests and pass the `--bless` flag
2020-02-04T15:52:34.8248773Z To only update this specific test, also pass `--test-args numeric/numeric-cast-3.rs`
2020-02-04T15:52:34.8248855Z error: 1 errors occurred comparing output.
2020-02-04T15:52:34.8248895Z status: exit code: 1
2020-02-04T15:52:34.8248895Z status: exit code: 1
2020-02-04T15:52:34.8249641Z command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/numeric/numeric-cast-3.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/numeric/numeric-cast-3" "-Crpath" "-O" "-Cdebuginfo=0" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/numeric/numeric-cast-3/auxiliary" "-A" "unused"
2020-02-04T15:52:34.8249941Z ------------------------------------------
2020-02-04T15:52:34.8249971Z 
2020-02-04T15:52:34.8250172Z ------------------------------------------
2020-02-04T15:52:34.8250234Z stderr:
---
2020-02-04T15:52:34.8251357Z 
2020-02-04T15:52:34.8251603Z error[E0689]: can't call method `try_into` on ambiguous numeric type `{integer}`
2020-02-04T15:52:34.8251819Z   --> /checkout/src/test/ui/numeric/numeric-cast-3.rs:5:38
2020-02-04T15:52:34.8251871Z    |
2020-02-04T15:52:34.8251927Z LL |     #[should_panic] let b: usize = 0.try_into().unwrap();
2020-02-04T15:52:34.8252012Z    |
2020-02-04T15:52:34.8252072Z help: you must specify a concrete type for this numeric value, like `i32`
2020-02-04T15:52:34.8252112Z    |
2020-02-04T15:52:34.8252112Z    |
2020-02-04T15:52:34.8252309Z LL |     #[should_panic] let b: usize = 0_i32.try_into().unwrap();
2020-02-04T15:52:34.8252411Z 
2020-02-04T15:52:34.8252450Z error: aborting due to 2 previous errors
2020-02-04T15:52:34.8252476Z 
2020-02-04T15:52:34.8252753Z For more information about this error, try `rustc --explain E0689`.
---
2020-02-04T15:52:34.8266445Z thread 'main' panicked at 'Some tests failed', src/tools/compiletest/src/main.rs:348:22
2020-02-04T15:52:34.8266674Z note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
2020-02-04T15:52:34.8276089Z 
2020-02-04T15:52:34.8276337Z 
2020-02-04T15:52:34.8278245Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-7/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "7.0.0\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
2020-02-04T15:52:34.8278726Z 
2020-02-04T15:52:34.8278870Z 
2020-02-04T15:52:34.8285079Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
2020-02-04T15:52:34.8285284Z Build completed unsuccessfully in 0:58:17
2020-02-04T15:52:34.8285284Z Build completed unsuccessfully in 0:58:17
2020-02-04T15:52:34.8336744Z == clock drift check ==
2020-02-04T15:52:34.8355624Z   local time: Tue Feb  4 15:52:34 UTC 2020
2020-02-04T15:52:35.1052097Z   network time: Tue, 04 Feb 2020 15:52:35 GMT
2020-02-04T15:52:35.1058557Z == end clock drift check ==
2020-02-04T15:52:35.4820732Z 
2020-02-04T15:52:35.4890432Z ##[error]Bash exited with code '1'.
2020-02-04T15:52:35.4906232Z ##[section]Finishing: Run build
2020-02-04T15:52:35.4937044Z ##[section]Starting: Checkout rust-lang/rust@refs/pull/68825/merge to s
2020-02-04T15:52:35.4939422Z Task         : Get sources
2020-02-04T15:52:35.4939472Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.
2020-02-04T15:52:35.4939539Z Version      : 1.0.0
2020-02-04T15:52:35.4939759Z Author       : Microsoft
2020-02-04T15:52:35.4939759Z Author       : Microsoft
2020-02-04T15:52:35.4939805Z Help         : [More Information](https://go.microsoft.com/fwlink/?LinkId=798199)
2020-02-04T15:52:35.4939914Z ==============================================================================
2020-02-04T15:52:35.9170054Z Cleaning any cached credential from repository: rust-lang/rust (GitHub)
2020-02-04T15:52:35.9208048Z ##[section]Finishing: Checkout rust-lang/rust@refs/pull/68825/merge to s
2020-02-04T15:52:35.9310002Z Cleaning up task key
2020-02-04T15:52:35.9310631Z Start cleaning up orphan processes.
2020-02-04T15:52:35.9420486Z Terminate orphan process: pid (3745) (python)
2020-02-04T15:52:35.9667736Z ##[section]Finishing: Finalize Job

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)

jyn514 · 2020-02-04T16:45:34Z

This doesn't work, but I'm not sure how to fix it ...

---- [ui] ui/numeric/numeric-cast-3.rs stdout ----

error: ui test compiled successfully!
status: exit code: 0
command: "/home/joshua/rustc/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/home/joshua/rustc/src/test/ui/numeric/numeric-cast-3.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/home/joshua/rustc/build/x86_64-unknown-linux-gnu/test/ui/numeric/numeric-cast-3" "-Crpath" "-O" "-Cdebuginfo=0" "-Zunstable-options" "-Lnative=/home/joshua/rustc/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/home/joshua/rustc/build/x86_64-unknown-linux-gnu/test/ui/numeric/numeric-cast-3/auxiliary" "-A" "unused"
stdout:
------------------------------------------

------------------------------------------
stderr:
------------------------------------------

------------------------------------------



failures:
    [ui] ui/numeric/numeric-cast-3.rs

test result: FAILED. 0 passed; 1 failed; 16 ignored; 0 measured; 9566 filtered out

JohnTitor · 2020-02-04T17:29:11Z

@jyn514 You should add check-pass flag to the test, like this:

// check-pass
use std::num::NonZeroUsize;
use std::convert::TryInto;
...

We're going {integer} -> NonZero{integer}, not the reverse

dtolnay

Could you give a real world example where this impl would be needed?

The test shows let a: NonZeroUsize = 1_usize.try_into().unwrap(); but this isn't actually a thing we would expect anyone to write, right?

jyn514 · 2020-02-08T02:41:34Z

That's code that I tried to write just now, it's why I made the PR.

 181             match usize::from_str_radix(s, 10) {
 182                 Ok(0) => Ok(None),
                     // this would be nicer as `Ok(i) => Ok(Some(i.try_into().unwrap()))`
 183                 Ok(i) => Ok(Some(NonZeroUsize::new(i).unwrap())),
 184                 Err(e) => Err(e),
 185             }

I could use unsafe here but I'd really rather not.

jyn514 · 2020-02-08T02:43:30Z

#22639 would also have fixed my problem.

dtolnay · 2020-02-08T03:13:01Z

I would recommend writing that snippet much more concisely as:

s.parse().map(NonZeroUsize::new)

Overall I'm not sure I buy the advantage of the genericism of TryFrom over the existing new constructors, so I'll go ahead and close this. Thanks anyway!

suggested in rust-lang/rust#68825 (comment)

jyn514 · 2020-02-08T03:36:53Z

That snippet is indeed a lot nicer, thank you!

suggested in rust-lang/rust#68825 (comment)

impl TryFrom<{integer}> for NonZero{integer}

680bec2

rust-highfive assigned dtolnay Feb 4, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Feb 4, 2020

jonas-schievink added relnotes Marks issues that should be documented in the release notes of the next release. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Feb 4, 2020

jonas-schievink added this to the 1.43 milestone Feb 4, 2020

make the tests compile

673caa4

jyn514 added 3 commits February 4, 2020 12:37

mark that the test should pass

7d703cb

don't build test unnecessarily

86cb122

fix doc comment

dec1f3c

We're going {integer} -> NonZero{integer}, not the reverse

dtolnay reviewed Feb 7, 2020

View reviewed changes

dtolnay closed this Feb 8, 2020

jyn514 added a commit to jyn514/saltwater that referenced this pull request Feb 8, 2020

make string parsing nicer

392f7f1

suggested in rust-lang/rust#68825 (comment)

jyn514 mentioned this pull request Feb 8, 2020

make string parsing nicer jyn514/saltwater#254

Merged

jyn514 added a commit to jyn514/saltwater that referenced this pull request Feb 8, 2020

make string parsing nicer

676630c

suggested in rust-lang/rust#68825 (comment)

Centril removed the relnotes Marks issues that should be documented in the release notes of the next release. label Mar 10, 2020

Centril removed this from the 1.43 milestone Mar 10, 2020

jyn514 mentioned this pull request Jun 16, 2020

Add TryFrom<{int}> for NonZero{int} #72717

Merged

jyn514 deleted the try-from-nonzero-usize branch September 12, 2020 03:30

jyn514 added a commit to jyn514/saltwater that referenced this pull request Feb 4, 2025

make string parsing nicer

f90b3e3

suggested in rust-lang/rust#68825 (comment)

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impl TryFrom<{integer}> for NonZero{integer}#68825