compiler: Hint at multiple crate versions if trait impl is for wrong ADT #146874

Enselic · 2025-09-22T06:03:14Z

If a user does e.g.

impl From<Bar> for foo::Foo

and get a compilation error about that From<Bar> is not implemented for Foo, check if multiple versions of the crate with Foo is present in the dependency graph. If so, give a hint about it.

Note that a test is added as a separate commit so it is easy to see what effect the fix has on the emitted error message.

This can be seen as a continuation of #124944.

I think this closes RUST-71693 but I haven't checked since it lacks a minimal reproducer. If this gets merged I'll ask that reporter if this fix works for them.

Real world example

I encountered this case in the wild and didn't realize I had multiple versions of a crate in my dependency graph. So I was a bit confused at first. For reference, here is what that looked like.

Click to expand

Before fix

error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied
   --> src/main.rs:73:5
    |
73  |     lambda_http::run(service_fn(handle_event)).await
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic`
    |
    = help: the following other types implement trait `From<T>`:
              `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>`
    = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>`
note: required by a bound in `lambda_http::run`
   --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26
    |
194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error>
    |              --- required by a bound in this function
...
199 |     E: std::fmt::Debug + Into<Diagnostic>,
    |                          ^^^^^^^^^^^^^^^^ required by this bound in `run`

error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied
   --> src/main.rs:73:48
    |
73  |     lambda_http::run(service_fn(handle_event)).await
    |                                                ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic`
    |
    = help: the following other types implement trait `From<T>`:
              `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>`
    = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>`
note: required by a bound in `lambda_http::run`
   --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26
    |
194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error>
    |              --- required by a bound in this function
...
199 |     E: std::fmt::Debug + Into<Diagnostic>,
    |                          ^^^^^^^^^^^^^^^^ required by this bound in `run`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors

After fix

   Compiling auto-merge-dependabot-pull-requests-webhook v0.1.0 (/home/martin/src/auto-merge-dependabot-prs/rust-webhook)
error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied
   --> src/main.rs:73:5
    |
 73 |     lambda_http::run(service_fn(handle_event)).await
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic`
    |
help: item with same name found
   --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1
    |
 43 | pub struct Diagnostic {
    | ^^^^^^^^^^^^^^^^^^^^^
    = note: perhaps two different versions of crate `lambda_runtime` are being used?
    = help: the following other types implement trait `From<T>`:
              `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>`
    = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>`
note: required by a bound in `lambda_http::run`
   --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26
    |
194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error>
    |              --- required by a bound in this function
...
199 |     E: std::fmt::Debug + Into<Diagnostic>,
    |                          ^^^^^^^^^^^^^^^^ required by this bound in `run`

error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied
   --> src/main.rs:73:48
    |
 73 |     lambda_http::run(service_fn(handle_event)).await
    |                                                ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic`
    |
help: item with same name found
   --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1
    |
 43 | pub struct Diagnostic {
    | ^^^^^^^^^^^^^^^^^^^^^
    = note: perhaps two different versions of crate `lambda_runtime` are being used?
    = help: the following other types implement trait `From<T>`:
              `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>`
              `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>`
    = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>`
note: required by a bound in `lambda_http::run`
   --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26
    |
194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error>
    |              --- required by a bound in this function
...
199 |     E: std::fmt::Debug + Into<Diagnostic>,
    |                          ^^^^^^^^^^^^^^^^ required by this bound in `run`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors

try-job: dist-various-1

rustbot · 2025-09-22T06:03:20Z

r? @jieyouxu

rustbot has assigned @jieyouxu.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

fmease · 2025-09-22T06:24:23Z

I haven't compared the two PRs but CC open PR #144674 which also touches this function.

Enselic · 2025-09-22T14:24:19Z

I haven't compared the two PRs but CC open PR #144674 which also touches this function.

👍 Here I and the author of that PR agreed that the PRs are orthogonal feature-wise and can be merged independently. Any merge conflicts are expected to be easy to resolve.

tests/run-make/crate-loading: Rename source files for clarity For rust-lang#146874 I originally tried to extend the existing test **tests/run-make/crate-loading**. That didn't work out since adding a re-export of the entire crate significantly changes the emitted error messsage. I did put some effort into making that test easier to understand however, by renaming its files. (Since I was confused myself at first.) Let's save some time for future devs by doing just the renames. Further cleanups are possible, but that will change the blessed output, so let's not do that right now. r? `@jieyouxu` since you have the context of rust-lang#146874

tests/run-make/crate-loading: Rename source files for clarity For rust-lang#146874 I originally tried to extend the existing test **tests/run-make/crate-loading**. That didn't work out since adding a re-export of the entire crate significantly changes the emitted error messsage. I did put some effort into making that test easier to understand however, by renaming its files. (Since I was confused myself at first.) Let's save some time for future devs by doing just the renames. Further cleanups are possible, but that will change the blessed output, so let's not do that right now. r? ``@jieyouxu`` since you have the context of rust-lang#146874

tests/run-make/crate-loading: Rename source files for clarity For rust-lang#146874 I originally tried to extend the existing test **tests/run-make/crate-loading**. That didn't work out since adding a re-export of the entire crate significantly changes the emitted error messsage. I did put some effort into making that test easier to understand however, by renaming its files. (Since I was confused myself at first.) Let's save some time for future devs by doing just the renames. Further cleanups are possible, but that will change the blessed output, so let's not do that right now. r? ```@jieyouxu``` since you have the context of rust-lang#146874

Rollup merge of #146875 - Enselic:better-file-names, r=jieyouxu tests/run-make/crate-loading: Rename source files for clarity For #146874 I originally tried to extend the existing test **tests/run-make/crate-loading**. That didn't work out since adding a re-export of the entire crate significantly changes the emitted error messsage. I did put some effort into making that test easier to understand however, by renaming its files. (Since I was confused myself at first.) Let's save some time for future devs by doing just the renames. Further cleanups are possible, but that will change the blessed output, so let's not do that right now. r? ```@jieyouxu``` since you have the context of #146874

tests/run-make/crate-loading: Rename source files for clarity For rust-lang#146874 I originally tried to extend the existing test **tests/run-make/crate-loading**. That didn't work out since adding a re-export of the entire crate significantly changes the emitted error messsage. I did put some effort into making that test easier to understand however, by renaming its files. (Since I was confused myself at first.) Let's save some time for future devs by doing just the renames. Further cleanups are possible, but that will change the blessed output, so let's not do that right now. r? ```@jieyouxu``` since you have the context of rust-lang#146874

jieyouxu

Thanks

View changes since this review

jieyouxu · 2025-10-04T07:55:52Z

@bors r+

bors · 2025-10-04T07:55:55Z

📌 Commit 141cada has been approved by jieyouxu

It is now in the queue for this repository.

…ieyouxu compiler: Hint at multiple crate versions if trait impl is for wrong ADT If a user does e.g. impl From<Bar> for foo::Foo and get a compilation error about that `From<Bar>` is not implemented for `Foo`, check if multiple versions of the crate with `Foo` is present in the dependency graph. If so, give a hint about it. Note that a test is added as a separate commit so it is easy to see what effect the fix has on the emitted error message. This can be seen as a continuation of rust-lang#124944. I think this closes RUST-71693 but I haven't checked since it lacks a minimal reproducer. If this gets merged I'll ask that reporter if this fix works for them. ## Real world example I encountered this case in the wild and didn't realize I had multiple versions of a crate in my dependency graph. So I was a bit confused at first. For reference, here is what that looked like. <details> <summary>Click to expand</summary> ### Before fix ``` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:5 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:48 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` For more information about this error, try `rustc --explain E0277`. error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors ``` ### After fix ``` Compiling auto-merge-dependabot-pull-requests-webhook v0.1.0 (/home/martin/src/auto-merge-dependabot-prs/rust-webhook) error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:5 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | help: item with same name found --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1 | 43 | pub struct Diagnostic { | ^^^^^^^^^^^^^^^^^^^^^ = note: perhaps two different versions of crate `lambda_runtime` are being used? = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:48 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | help: item with same name found --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1 | 43 | pub struct Diagnostic { | ^^^^^^^^^^^^^^^^^^^^^ = note: perhaps two different versions of crate `lambda_runtime` are being used? = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` For more information about this error, try `rustc --explain E0277`. error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors ``` </details>

Rollup of 14 pull requests Successful merges: - #142670 (Document fully-qualified syntax in `as`' keyword doc) - #145685 (add CloneFromCell and Cell::get_cloned) - #146330 (Bump unicode_data and printables to version 17.0.0) - #146451 (Fix atan2 inaccuracy in documentation) - #146479 (add mem::conjure_zst) - #146874 (compiler: Hint at multiple crate versions if trait impl is for wrong ADT ) - #147117 (interpret `#[used]` as `#[used(compiler)]` on illumos) - #147190 (std: `sys::net` cleanups) - #147251 (Do not assert that a change in global cache only happens when concurrent) - #147280 (Return to needs-llvm-components being info-only) - #147288 (compiletest: Make `DirectiveLine` responsible for name/value splitting) - #147309 (Add documentation about unwinding to wasm targets) - #147315 (bless autodiff batching test) - #147323 (Fix top level ui tests check in tidy) r? `@ghost` `@rustbot` modify labels: rollup

matthiaskrgr · 2025-10-04T10:32:53Z

@bors r-
#147326 (comment)

tests/run-make/duplicate-dependency/rmake.rs

jieyouxu · 2025-10-04T10:40:50Z

@bors2 delegate=try

rust-bors · 2025-10-04T10:40:52Z

✌️ @Enselic, you can now perform try builds on this pull request!

You can now post @bors2 try to start a try build.

If a user does e.g. impl From<Bar> for foo::Foo and get a compilation error about that `From<Bar>` is not implemented for `Foo`, check if multiple versions of the crate with `Foo` is present in the dependency graph. If so, give a hint about it. I encountered this case in the wild and didn't realize I had multiple versions of a crate in my dependency graph. So I was a bit confused at first. This fix will make life easier for others.

Enselic · 2025-10-04T20:09:12Z

@bors2 try

compiler: Hint at multiple crate versions if trait impl is for wrong ADT try-job: dist-various-1

rust-bors · 2025-10-04T21:36:13Z

☀️ Try build successful (CI)
Build commit: 6138032 (61380325129b5bd86a9a3573f74ea63ac3f76f58, parent: 99ca0ae87ba5571acee116ea83d1f9e88a7bf8d8)

Enselic · 2025-10-04T22:19:39Z

@jieyouxu thanks, that seems to work. Diff from previous approve is this.

@rustbot ready

jieyouxu · 2025-10-05T06:01:56Z

@bors r+

bors · 2025-10-05T06:01:59Z

📌 Commit f6d5d3e has been approved by jieyouxu

It is now in the queue for this repository.

…ieyouxu compiler: Hint at multiple crate versions if trait impl is for wrong ADT If a user does e.g. impl From<Bar> for foo::Foo and get a compilation error about that `From<Bar>` is not implemented for `Foo`, check if multiple versions of the crate with `Foo` is present in the dependency graph. If so, give a hint about it. Note that a test is added as a separate commit so it is easy to see what effect the fix has on the emitted error message. This can be seen as a continuation of rust-lang#124944. I think this closes RUST-71693 but I haven't checked since it lacks a minimal reproducer. If this gets merged I'll ask that reporter if this fix works for them. ## Real world example I encountered this case in the wild and didn't realize I had multiple versions of a crate in my dependency graph. So I was a bit confused at first. For reference, here is what that looked like. <details> <summary>Click to expand</summary> ### Before fix ``` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:5 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:48 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` For more information about this error, try `rustc --explain E0277`. error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors ``` ### After fix ``` Compiling auto-merge-dependabot-pull-requests-webhook v0.1.0 (/home/martin/src/auto-merge-dependabot-prs/rust-webhook) error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:5 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | help: item with same name found --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1 | 43 | pub struct Diagnostic { | ^^^^^^^^^^^^^^^^^^^^^ = note: perhaps two different versions of crate `lambda_runtime` are being used? = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:48 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | help: item with same name found --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1 | 43 | pub struct Diagnostic { | ^^^^^^^^^^^^^^^^^^^^^ = note: perhaps two different versions of crate `lambda_runtime` are being used? = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` For more information about this error, try `rustc --explain E0277`. error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors ``` </details> try-job: dist-various-1

Rollup of 3 pull requests Successful merges: - #146874 (compiler: Hint at multiple crate versions if trait impl is for wrong ADT ) - #147262 (Make #[link="dl"] an FCW rather than an error) - #147364 (update autodiff testcases) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2025-10-05T10:43:13Z

⌛ Testing commit f6d5d3e with merge 0ec8b69...

compiler: Hint at multiple crate versions if trait impl is for wrong ADT If a user does e.g. impl From<Bar> for foo::Foo and get a compilation error about that `From<Bar>` is not implemented for `Foo`, check if multiple versions of the crate with `Foo` is present in the dependency graph. If so, give a hint about it. Note that a test is added as a separate commit so it is easy to see what effect the fix has on the emitted error message. This can be seen as a continuation of #124944. I think this closes RUST-71693 but I haven't checked since it lacks a minimal reproducer. If this gets merged I'll ask that reporter if this fix works for them. ## Real world example I encountered this case in the wild and didn't realize I had multiple versions of a crate in my dependency graph. So I was a bit confused at first. For reference, here is what that looked like. <details> <summary>Click to expand</summary> ### Before fix ``` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:5 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:48 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` For more information about this error, try `rustc --explain E0277`. error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors ``` ### After fix ``` Compiling auto-merge-dependabot-pull-requests-webhook v0.1.0 (/home/martin/src/auto-merge-dependabot-prs/rust-webhook) error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:5 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | help: item with same name found --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1 | 43 | pub struct Diagnostic { | ^^^^^^^^^^^^^^^^^^^^^ = note: perhaps two different versions of crate `lambda_runtime` are being used? = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` error[E0277]: the trait bound `lambda_http::lambda_runtime::Diagnostic: From<Error>` is not satisfied --> src/main.rs:73:48 | 73 | lambda_http::run(service_fn(handle_event)).await | ^^^^^ the trait `From<Error>` is not implemented for `lambda_http::lambda_runtime::Diagnostic` | help: item with same name found --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_runtime-0.13.0/src/diagnostic.rs:43:1 | 43 | pub struct Diagnostic { | ^^^^^^^^^^^^^^^^^^^^^ = note: perhaps two different versions of crate `lambda_runtime` are being used? = help: the following other types implement trait `From<T>`: `lambda_http::lambda_runtime::Diagnostic` implements `From<&str>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError + Send + Sync>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Box<dyn StdError>>` `lambda_http::lambda_runtime::Diagnostic` implements `From<Infallible>` `lambda_http::lambda_runtime::Diagnostic` implements `From<lambda_runtime::deserializer::DeserializeError>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::io::Error>` `lambda_http::lambda_runtime::Diagnostic` implements `From<std::string::String>` = note: required for `Error` to implement `Into<lambda_http::lambda_runtime::Diagnostic>` note: required by a bound in `lambda_http::run` --> /home/martin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/lambda_http-0.17.0/src/lib.rs:199:26 | 194 | pub async fn run<'a, R, S, E>(handler: S) -> Result<(), Error> | --- required by a bound in this function ... 199 | E: std::fmt::Debug + Into<Diagnostic>, | ^^^^^^^^^^^^^^^^ required by this bound in `run` For more information about this error, try `rustc --explain E0277`. error: could not compile `auto-merge-dependabot-pull-requests-webhook` (bin "auto-merge-dependabot-pull-requests-webhook") due to 2 previous errors ``` </details> try-job: dist-various-1

tests: Check error when struct from wrong crate version is used for impl

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rustbot assigned jieyouxu Sep 22, 2025

rustbot added A-run-make Area: port run-make Makefiles to rmake.rs S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 22, 2025

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tests/run-make/crate-loading: Rename source files for clarity #146875

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Rollup of 14 pull requests #147326

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Enselic force-pushed the multiple-adt-versions branch from 141cada to f6d5d3e Compare October 4, 2025 12:19

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rust-bors bot added a commit that referenced this pull request Oct 4, 2025

Auto merge of #146874 - Enselic:multiple-adt-versions, r=<try>

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compiler: Hint at multiple crate versions if trait impl is for wrong ADT try-job: dist-various-1

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Rollup of 3 pull requests #147366

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