When compiling without a specified `--edition`, emit a note by estebank · Pull Request #158102 · rust-lang/rust

estebank · 2026-06-18T20:28:57Z

No description provided.

estebank · 2026-06-18T20:39:23Z

I'll try to write an MCP later (unless someone does it for me). This change was motivated after seeing https://internals.rust-lang.org/t/code-compiles-on-playground-but-fails-when-passed-via-stdin-to-rustc/24393 where the different defaults between cargo, playground and rustc caused people to get confused.

rustbot · 2026-07-21T02:25:26Z

Some changes occurred in src/tools/compiletest

cc @jieyouxu

rustbot · 2026-07-21T02:25:29Z

r? @jieyouxu

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jieyouxu

Thanks
@bors r+ rollup

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jieyouxu · 2026-08-04T01:02:33Z


 fn main() {
-    rustc().input("foo-prev.rs").run();
+    rustc().edition("2015").input("foo-prev.rs").run();


Remark: we could consider default setting edition but allow overriding, but explicit is fine

rust-bors · 2026-08-04T01:05:18Z

📌 Commit a1d6de2 has been approved by jieyouxu

It is now in the queue for this repository.

…ieyouxu When compiling without a specified `--edition`, emit a note

jhpratt · 2026-08-04T04:39:49Z

@bors r- #160481 (comment)

---- messages::deduplicate_errors stdout ----
running `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/cargo test -j1`

thread 'messages::deduplicate_errors' (114996) panicked at src/tools/cargo/tests/testsuite/messages.rs:163:10:

--- Expected
++++ actual:   stderr
   1    1 | [COMPILING] foo v0.0.1 ([ROOT]/foo)
   2      - [NOTE] `--edition` is unspecified, defaulting to `2015` while the latest is `2024`; it must be one of: <2015|2018|2021|2024|future>
   3      - 
   4    2 | [ERROR] expected one of `!` or `::`, found `should`
   5    3 |  --> src/lib.rs:2:22
   6    4 |   |
   7    5 | 2 |                 this should not compile
   8    6 |   |                      ^^^^^^ expected one of `!` or `::`
   9    7 | 
  10    8 | [ERROR] could not compile `foo` (lib) due to 1 previous error



---- messages::deduplicate_errors stdout end ----
---- messages::deduplicate_messages_basic stdout ----
running `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/cargo test --no-run -j1`

thread 'messages::deduplicate_messages_basic' (115030) panicked at src/tools/cargo/tests/testsuite/messages.rs:87:10:

--- Expected
++++ actual:   stderr
   1    1 | [COMPILING] foo v0.0.1 ([ROOT]/foo)
   2      - [NOTE] `--edition` is unspecified, defaulting to `2015` while the latest is `2024`; it must be one of: <2015|2018|2021|2024|future>
   3      - 
   4    2 | [WARNING] unused variable: `x`
   5    3 |  --> src/lib.rs:3:25
   6    4 |   |
   7    5 | 3 |                     let x = 1;
   8    6 |   |                         ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
   9    7 |   |
  10    8 |   = [NOTE] `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
  11    9 | 
  12      - [WARNING] `foo` (lib) generated 1 warning[..]
       10 + [WARNING] `foo` (lib) generated 1 warning (run `cargo fix --lib -p foo` to apply 1 suggestion)
  13   11 | [WARNING] `foo` (lib test) generated 1 warning (1 duplicate)
  14   12 | [FINISHED] `test` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
  15      - [EXECUTABLE] unittests src/lib.rs (target/debug/deps/foo-[HASH][EXE])
       13 + [EXECUTABLE] unittests src/lib.rs (target/debug/deps/foo-[HASH])



---- messages::deduplicate_messages_basic stdout end ----

rust-bors · 2026-08-04T04:39:57Z

This pull request was unapproved.

This PR was contained in a rollup (#160481), which was unapproved.

View changes since this unapproval

As part of notifying users calling bare `rustc` without an explicit edition that they should likely be using the 2024 edition, update cargo tests to not trigger the new user facing note. This change will let rust-lang/rust#158102 to land.

rustbot · 2026-09-15T19:35:41Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

jieyouxu

Some nits
@rustbot author

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jieyouxu · 2026-09-16T14:15:09Z

@@ -0,0 +1,2 @@
+note: it is advisable to explicitly specify the `--edition` argument (the default implies `2015`); it must be one of: <2015|2018|2021|2024|future>


Non-blocking: I wonder if we want to filter out future, since you can't really use this successfully 🤔

jieyouxu · 2026-09-16T14:24:31Z

+        let TestProps { mut compile_flags, run_flags, .. } = props;
+        // We don't want to pass `--edition=2015` in, which is being set by default by
+        // `TestProps::from_file`.
+        compile_flags.remove(0);


~~Instead of adding then removing, can we stop presetting --edition=2015 in TestProps::from_file for rustdoc-gui test mode?~~ Actually I'll look at this later, this has some funky behavior in general.

rustbot · 2026-09-16T14:25:34Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

jieyouxu · 2026-09-16T14:39:35Z

+    rustc().edition("2015").input("main.rs").run().assert_stderr_not_contains("--edition");
+    let out = rustc().input("main.rs").run().assert_stderr_contains("--edition").stderr_utf8();
+    diff().expected_file("unspecified-edition.stderr").actual_text("(rustc)", &out).run();


Can we also exercise rustdoc's interface here?

Could we also add a case for just e.g. --help or sth that doesn't have inputs?

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jieyouxu · 2026-09-16T14:40:44Z

        }

-        let edition = config::parse_crate_edition(early_dcx, matches);
+        let edition = config::parse_crate_edition(early_dcx, matches, true);


I think this also fires for rustdoc unconditionally, even if it doesn't have inputs? 🤔 I want to say rustdoc has some fake inputs or something? There's something weird about this being unconditionally true.

View changes since the review

jieyouxu · 2026-09-16T14:42:00Z

+    /// We should not be emitting notes during compiles, with the *only* exception of missing
+    /// `--crate` when calling `rustc` directly.


Wait, this should say --edition not --crate, right?

View changes since the review

jieyouxu · 2026-09-16T15:01:08Z

Actually, now that I think about it, can we also add a run-make-cargo test for a cargo project that doesn't explicit set an edition? I don't remember if cargo explicitly sets an edition if Cargo.toml doesn't have it 🤔

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estebank force-pushed the note-default-edition branch from b923a75 to 2a486d3 Compare June 18, 2026 20:41

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estebank force-pushed the note-default-edition branch from 4241536 to d71c2fa Compare July 21, 2026 02:17

estebank mentioned this pull request Jul 21, 2026

Emit note when calling rustc without specifying an edition rust-lang/compiler-team#1019

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estebank added the S-blocked Status: Blocked on something else such as an RFC or other implementation work. label Jul 21, 2026

estebank marked this pull request as ready for review July 21, 2026 02:25

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jieyouxu removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 25, 2026

estebank force-pushed the note-default-edition branch from d71c2fa to a1d6de2 Compare July 27, 2026 06:56

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estebank added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-blocked Status: Blocked on something else such as an RFC or other implementation work. labels Aug 3, 2026

jieyouxu approved these changes Aug 4, 2026

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jhpratt added a commit to jhpratt/rust that referenced this pull request Aug 4, 2026

Rollup merge of rust-lang#158102 - estebank:note-default-edition, r=j…

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…ieyouxu When compiling without a specified `--edition`, emit a note

jhpratt mentioned this pull request Aug 4, 2026

Rollup of 29 pull requests #160481

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estebank force-pushed the note-default-edition branch from a1d6de2 to a25876f Compare September 13, 2026 23:31

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estebank mentioned this pull request Sep 13, 2026

Specify --edition in messages tests rust-lang/cargo#17470

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cubic-dev-ai Bot mentioned this pull request Sep 14, 2026

[pull] master from rust-lang:master coleleavitt/cargo#83

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estebank added 6 commits September 15, 2026 19:28

When compiling without a specified --edition, emit a note

9fd5396

Use same wording as cargo does when package.edition is unspecified

db0d1a6

Remove --edition=2015 from rustdoc-gui tests only

39b4e3c

fix run-make test

e5969e8

Re-add the hability to emit notes exclusively for missing --edition

bb3600a

Fix test

ed8f499

estebank force-pushed the note-default-edition branch from a25876f to ed8f499 Compare September 15, 2026 19:35

jieyouxu added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 16, 2026

jieyouxu reviewed Sep 16, 2026

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jieyouxu reviewed Sep 16, 2026

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		@@ -0,0 +1,2 @@
		note: it is advisable to explicitly specify the `--edition` argument (the default implies `2015`); it must be one of: <2015\|2018\|2021\|2024\|future>

		/// We should not be emitting notes during compiles, with the only exception of missing
		/// `--crate` when calling `rustc` directly.

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