fix: Update proc-macro2 usage for latest nightly

[cryptopapi997]

As of nightly-2025-04-16, SourceFile and the methods around it don't exist anymore, so anyone updating rust or installing rust won't be able to compile the idl anymore. proc-macro2 already updated, this PR updates anchor accordingly. Note that this will require users to update to the latest nightly (and will break users with an older nightly). Idk if this counts as a breaking change since it only affects nightly...

Fixes #3662

[tobaccorico]

as far as I can tell it also affects stable, not only nightly (at least on my local build)

[kingmanas]

Replace the respective error line with

📁 File:

defined.rs

📝 Line 499:

let source_path = proc_macro2::Span::call_site().file();

[Rayato159]

I'm facing this problem too even though I use stable version of rustc.

[RealAyyo]

same. Not only nightly

[acheroncrypto]

Thanks for the quick fix.

We're also planning to make the IDL generation use the stable compiler by default and make code that required nightly optional via a CLI flag to avoid issues like this one. It sounds like these methods will be stabilized (as mentioned in rust-lang/rust#139671), so we might be able to avoid nightly completely when that happens.

Related: There is an open issue (rust-lang/rust#139903) regarding the naming of local_file.

[hryer]

Is anything that I can help maybe?, I need this fix ASAP. Also, I want to tell the CI failed

no method named `source_file` found for struct `proc_macro2::Span` in the current scope
   --> /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/anchor-syn-0.31.0/src/idl/defined.rs:499:66
    |
499 |                 let source_path = proc_macro2::Span::call_site().source_file().path();
    |                                                                  ^^^^^^^^^^^ method not found in `Span`

[jacobcreech]

@hryer we're waiting on the update and I'll check into the CI

[andreisilviudragnea]

Hello. Is this going to be released as a hotfix for Anchor v0.31.0?

[quanghuynguyen1902]

Please fix it ASAP.

[moribus-single]

having the same issue
even in the new empty anchor project

[tobaccorico]

having the same issue even in the new empty anchor project

this is the temporary fix that worked best for me:
https://solana.stackexchange.com/a/21560/39751

[conceitodigital]

Facing the same issue.

[romeoscript]

source_path

i can't find this file , where would i locate it ?

[iamramtin]

Using anchor build --no-idl works as a temporary workaround (tested on Anchor v0.30.1)

[romeoscript]

Using anchor build --no-idl works as a temporary workaround (tested on Anchor v0.30.1)

so how do i generate IDL for frontend use ?

[acheroncrypto]

We're most likely going to make a patch release for this issue. Thanks for the fix and also responsiveness!

[adama789]

Hi, how to pull these changes? Will it be released in anchor 0.31.1?

[Vinayapr23]

How will these changes be reflected? In anchor 0.31.1 ?
So what to do with current 0.31.0 in the meantime

[stevensanborn]

anchor-cli 0.31.0
rustc 1.88.0-nightly (191df20fc 2025-04-18)
adding to cargo toml worked for me :
proc-macro2 = { version = "1.0.95"}

[h0lme3]

Is it fixed?

[0xJamesBong]

So what's the solution?

[Vinayapr23]

So what's the solution?

Update to anchor 0.31.1 which was released today

[h0lme3]

So what's the solution?

Update to anchor 0.31.1 which was released today

please check the issue, I figured out the issue yesterday but today I am facing a new issue
#3676 (comment)

[0xm4ud]

@hryer this line: let source_path = proc_macro2::Span::call_site().source_file().path();
into this: let source_path = proc_macro2::Span::call_site().file().to_string();

[cryptopapi997]

For anyone still runing into this issue:

Make sure you're using

• anchor v0.31.1
• latest rust nightly
• proc_macro2 v0.1.95 in your cargo.lock

[rotcan]

Getting below error while using

• anchor v0.31.1
• rust nightly-2025-04-21
• proc_macro2 v0.1.95

Error

no method named file found for reference &proc_macro::Span in the current scope
|
465 | Span::Compiler(s) => s.file(),
| ^^^^ method not found in &Span

error[E0599]: no method named local_file found for reference &proc_macro::Span in the current scope
|
473 | Span::Compiler(s) => s.local_file(),
| ^^^^^^^^^^ method not found in &Span

[0xm4ud]

@rotcan

Getting below error while using

• anchor v0.31.1
• rust nightly-2025-04-21
• proc_macro2 v0.1.95

Error

no method named file found for reference &proc_macro::Span in the current scope | 465 | Span::Compiler(s) => s.file(), | ^^^^ method not found in &Span

error[E0599]: no method named local_file found for reference &proc_macro::Span in the current scope | 473 | Span::Compiler(s) => s.local_file(), | ^^^^^^^^^^ method not found in &Span

have you tried reverting proc_macro2 v0.1.95 to proc_macro2 v0.1.94?

[rotcan]

Hi @0xm4ud ,

@rotcan

Getting below error while using

• anchor v0.31.1
• rust nightly-2025-04-21
• proc_macro2 v0.1.95

Error
no method named file found for reference &proc_macro::Span in the current scope | 465 | Span::Compiler(s) => s.file(), | ^^^^ method not found in &Span
error[E0599]: no method named local_file found for reference &proc_macro::Span in the current scope | 473 | Span::Compiler(s) => s.local_file(), | ^^^^^^^^^^ method not found in &Span

have you tried reverting proc_macro2 v0.1.95 to proc_macro2 v0.1.94?

With below configuration

• anchor v0.31.1
• rust nightly - 2025-04-21
• proc_macro2 v0.1.94
• solana - 2.1.4

I am getting this error

no method named file found for struct proc_macro2::Span in the current scope
--> /.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/anchor-syn-0.31.1/src/idl/defined.rs:501:22
|
500 | let source_path = proc_macro2::Span::call_site()
| ______________-
501 | | .file()
| | -^^^^ method not found in Span
| ||
|

[0xm4ud]

@rotcan I saw that error this morning. What I did was: cargo update -p proc-macro2, rustup override set 1.81, which solved it for me.
btw I'm not running nightly.

[rotcan]

@0xm4ud , still getting same error with below setting :(

• anchor 0.31.1
• rust- 1.81
• proc_macro2 v0.1.94
• solana - 2.1.4

no method named file found for struct proc_macro2::Span in the current scope
--> /.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/anchor-syn-0.31.1/src/idl/defined.rs:501:22
|
500 | let source_path = proc_macro2::Span::call_site()
| ______________-
501 | | .file()
| | -^^^^ method not found in Span
| ||

[0xm4ud]

@rotcan hmm.. cargo update -p proc-macro2 should've changed/updated your proc-macro2 version, but by your post I see still is 1.94, try removing the lib /proc-macro2-1.0.94/directory and running cargo update -p proc-macro2 again.
Clean the project as well, and cargo clean before building it again.
Updating proc-macro2 v1.0.94 -> v1.0.95

[rotcan]

@0xm4ud Got it working thanks. I deleted proc-macro2-1.0.94 & 95 directory and anchor-syn-0.31.1 directory in cargo registry. Then ran rustup update.
Following config worked
rustup - 2025-04-21 nightly
anchor - 0.31.1
solana - 2.14.0
proc-macro2 - 1.0.95

[jgur-psyops]

Was confused by people saying you need nightly rust.

You don't need to be using nightly in your workspace, but you DO need to update your nightly because anchor idl generation uses it. Make sure you have run rustup update and your rustc 1.88.0-nightly in the resulting list is up to date. Your toolchain can be 1.81.0 or 1.79 stable without issue.

[el-tumero]

this works for me:

• anchor - 0.31.1
• solana - 2.1.0
• proc-macro2 - 1.0.95
• rust - 1.81.0