Add _value API for number literals in proc-macro

[GuillaumeGomez]

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Part of #136652.

This PR adds the *_value for numbers (integers and floats). However, f16 and f128 are voluntarily left out as they're still unstable. Adding support for them is just a matter of uncommenting two lines, so should be fine.

Setting same reviewer as last time.

r? @Urgau

[GuillaumeGomez]

My favourite kind of failure: works locally but not in CI. T_T

Updated the value in the tests to see which one exactly is failing.

[GuillaumeGomez]

Bug comes from an issue with GCC proc-macro ABI. Ignoring this test on GCC backend for now.

[GuillaumeGomez]

CI fixed. :)

[Urgau]

A libs (or maybe even libs-api) reviewer seems more appropriate to review this PR.

r? Amanieu (since you reviewed #136355)

[Urgau]

I missed it already has an accepted ACP. The PR can be reviewed by libs reviewer.

r? libs

[Mark-Simulacrum]

Is this exactly in sync with what the rustc parser permits?

I guess that would be a mix of https://doc.rust-lang.org/nightly/reference/tokens.html#grammar-INTEGER_LITERAL and whatever we then tokenize from it?

Perhaps this should go over the bridge and ask rustc to parse the string for us?

[GuillaumeGomez]

There is no code in rustc currently which would allow this conversion without including a lot of other things. My code is a simplified version of integer_lit (from rustc_ast/src/util/literal.rs) which parses both the number, its base and its suffix (which we already have) and returns a LitKind, which is also unnecessary here since we already know the end type.

[Mark-Simulacrum]

I think my question is not about specific code in rustc but rather whether the implementation here parses exactly the same literals that rustc would from the given token(s). Is that the case? Essentially, can we document these functions as being bug-for-bug compatible with what rustc would do, or do we need a separate grammar for this?

[GuillaumeGomez]

At this point, the compiler already ran on the literal so all errors have been checked already. The remaining potential errors mostly come from trying to convert a int/float not fitting the expected output.

[GuillaumeGomez]

Added the method for f16, renamed the function only_digits into strip_underscores and improve the code of parse_number a bit to remove allocations.

[GuillaumeGomez]

Forgot to change the status.

@rustbot ready

cc @Mark-Simulacrum

[Mark-Simulacrum]

Can you reply to my comment here? #154608 (comment)

@rustbot author

[GuillaumeGomez]

Forgot to do so. Answered it.

@rustbot ready

[GuillaumeGomez]

@bors try jobs=x86_64-mingw-1

[rust-bors]

💔 Test for f7e180c failed: CI. Failed job:

• try - x86_64-mingw-1 (web logs, enhanced plaintext logs)

[rust-log-analyzer]

The job x86_64-mingw-1 failed! Check out the build log: (web)(plain enhanced)(plain)

Click to see the possible cause of the failure (guessed by this bot)

failures:
---- [ui] tests\ui\proc-macro\test.rs stdout ----
error: auxiliary build of D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api/proc_macro_api_tests.rs failed to compile: status: exit code: 1
command: PATH="D:\a\rust\rust\build\x86_64-pc-windows-gnu\stage2\bin;D:\a\rust\rust\build\x86_64-pc-windows-gnu\bootstrap-tools\x86_64-pc-windows-gnu\release\deps;D:\a\rust\rust\ninja;D:\a\rust\rust\mingw64\bin;C:\msys64\usr\bin;D:\a\rust\rust\sccache;C:\Program Files\MongoDB\Server\7.0\bin;C:\vcpkg;C:\tools\zstd;C:\hostedtoolcache\windows\stack\3.9.3\x64;C:\cabal\bin;C:\ghcup\bin;C:\mingw64\bin;C:\Program Files\dotnet;C:\Program Files\MySQL\MySQL Server 8.0\bin;C:\Program Files\R\R-4.6.0\bin\x64;C:\SeleniumWebDrivers\GeckoDriver;C:\SeleniumWebDrivers\EdgeDriver;C:\SeleniumWebDrivers\ChromeDriver;C:\Program Files (x86)\sbt\bin;C:\Program Files (x86)\GitHub CLI;C:\Program Files\Git\bin;C:\Program Files (x86)\pipx_bin;C:\npm\prefix;C:\hostedtoolcache\windows\go\1.24.13\x64\bin;C:\hostedtoolcache\windows\Python\3.12.10\x64\Scripts;C:\hostedtoolcache\windows\Python\3.12.10\x64;C:\hostedtoolcache\windows\Ruby\3.3.11\x64\bin;C:\Program Files\OpenSSL\bin;C:\tools\kotlinc\bin;C:\hostedtoolcache\windows\Java_Temurin-Hotspot_jdk\17.0.19-10\x64\bin;C:\Program Files\ImageMagick-7.1.2-Q16-HDRI;C:\Program Files\Microsoft SDKs\Azure\CLI2\wbin;C:\ProgramData\kind;C:\ProgramData\Chocolatey\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0;C:\Windows\System32\OpenSSH;C:\Program Files\PowerShell\7;C:\Program Files\Microsoft\Web Platform Installer;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn;C:\Program Files\Microsoft SQL Server\150\Tools\Binn;C:\Program Files\dotnet;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit;C:\Program Files (x86)\WiX Toolset v3.14\bin;C:\Program Files\Microsoft SQL Server\130\DTS\Binn;C:\Program Files\Microsoft SQL Server\140\DTS\Binn;C:\Program Files\Microsoft SQL Server\150\DTS\Binn;C:\Program Files\Microsoft SQL Server\160\DTS\Binn;C:\Program Files\Microsoft SQL Server\170\DTS\Binn;C:\ProgramData\chocolatey\lib\pulumi\tools\Pulumi\bin;C:\Program Files\CMake\bin;C:\Strawberry\c\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\perl\bin;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.9.16\bin;C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code;C:\Program Files\Microsoft SDKs\Service Fabric\Tools\ServiceFabricLocalClusterManager;C:\Program Files\nodejs;C:\Program Files\Git\cmd;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\bin;C:\Program Files\GitHub CLI;C:\tools\php;C:\Program Files (x86)\sbt\bin;C:\Program Files\Amazon\AWSCLIV2;C:\Program Files\Amazon\SessionManagerPlugin\bin;C:\Program Files\Amazon\AWSSAMCLI\bin;C:\Program Files\Microsoft SQL Server\130\Tools\Binn;C:\Program Files\mongosh;C:\Program Files\LLVM\bin;C:\Program Files (x86)\LLVM\bin;C:\Users\runneradmin\.dotnet\tools;C:\Users\runneradmin\.cargo\bin;C:\Users\runneradmin\AppData\Local\Microsoft\WindowsApps" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\stage2\\bin\\rustc.exe" "D:\\a\\rust\\rust\\tests\\ui\\proc-macro\\auxiliary\\api/proc_macro_api_tests.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=C:\\Users\\runneradmin\\.cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=D:\\a\\rust\\rust\\vendor" "--sysroot" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\stage2" "--target=x86_64-pc-windows-gnu" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\test\\ui\\proc-macro\\test\\auxiliary" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=D:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\native\\rust-test-helpers" "--edition=2021" "--crate-type" "proc-macro" "--extern" "proc_macro" "-L" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\test\\ui\\proc-macro\\test\\auxiliary"
stdout: none
--- stderr -------------------------------
error[E0658]: `cfg(target_has_reliable_f16)` is experimental and subject to change
##[error] --> D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api\literal.rs:106:13
|
LL | if cfg!(target_has_reliable_f16) {
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= help: add `#![feature(cfg_target_has_reliable_f16_f128)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: `cfg(target_has_reliable_f16)` is experimental and subject to change
##[error] --> D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api\literal.rs:112:13
|
LL | if cfg!(target_has_reliable_f16) {
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= help: add `#![feature(cfg_target_has_reliable_f16_f128)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
warning: unexpected `cfg` condition name: `target_has_reliable_f16`
##[warning] --> D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api\literal.rs:106:13
|
LL | if cfg!(target_has_reliable_f16) {
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= help: expected names are: `FALSE` and `test` and 32 more
= help: to expect this configuration use `--check-cfg=cfg(target_has_reliable_f16)`
= note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
= note: `#[warn(unexpected_cfgs)]` on by default
warning: unexpected `cfg` condition name: `target_has_reliable_f16`
##[warning] --> D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api\literal.rs:112:13
|
LL | if cfg!(target_has_reliable_f16) {
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= help: to expect this configuration use `--check-cfg=cfg(target_has_reliable_f16)`
= note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
warning: the `#![feature]` attribute can only be used at the crate root
##[warning] --> D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api\literal.rs:3:1
|
LL | #![feature(f16)]
| ^^^^^^^^^^^^^^^^
|
= help: the crate root is at `D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api/proc_macro_api_tests.rs`
= note: `#[warn(unused_attributes)]` (part of `#[warn(unused)]`) on by default
warning: the `#![feature]` attribute can only be used at the crate root
##[warning] --> D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api\literal.rs:4:1
|
LL | #![feature(cfg_target_has_reliable_f16_f128)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: the crate root is at `D:\a\rust\rust\tests\ui\proc-macro\auxiliary\api/proc_macro_api_tests.rs`
error: aborting due to 2 previous errors; 4 warnings emitted
For more information about this error, try `rustc --explain E0658`.
------------------------------------------
---
Some tests failed in compiletest suite=ui mode=ui host=x86_64-pc-windows-gnu target=x86_64-pc-windows-gnu
Bootstrap failed while executing `test --stage 2 --skip=compiler --skip=src`
Build completed unsuccessfully in 1:51:31
make: *** [Makefile:126: ci-mingw-x] Error 1
local time: Sun Jun 7 21:21:33 CUT 2026
network time: Sun, 07 Jun 2026 21:21:33 GMT
##[error]Process completed with exit code 2.
##[group]Run echo "disk usage:"
echo "disk usage:"

[GuillaumeGomez]

@bors try jobs=x86_64-mingw-1

[rust-bors]

☀️ Try build successful (CI)
Build commit: ca0997c (ca0997c1d84db579967006af54f955603d699d43, parent: f20a92ec01483dc5c58e90e246f266bdad822d86)

[GuillaumeGomez]

@bors r=Mark-Simulacrum rollup

[rust-bors]

📌 Commit 48c52ae has been approved by Mark-Simulacrum

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened.

[panstromek]

@rust-timer build 35f7c69

[rust-timer]

Finished benchmarking commit (35f7c69): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -5.0%, secondary 6.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	6.4%	[6.4%, 6.4%]	1
Improvements ✅ (primary)	-5.0%	[-5.0%, -5.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-5.0%	[-5.0%, -5.0%]	1

Cycles

Results (secondary 3.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.1%	[3.1%, 3.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 1.6%, secondary 1.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.6%	[1.5%, 1.9%]	8
Regressions ❌ (secondary)	1.8%	[0.3%, 3.3%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.6%	[1.5%, 1.9%]	8

Bootstrap: 517.572s -> 516.06s (-0.29%)
Artifact size: 400.85 MiB -> 400.83 MiB (-0.00%)