Description
Bug Report
Some tracing macros can use the fields provided more than once causing confusing and non-local error messages.
Version
Discovered on 0.1.29, from a code read also looks to be present on master.
Crates
tracing
Description
#[derive(Debug)]
struct Foo;
#[derive(Debug)]
struct Bar(Foo);
pub fn foo(foo: Foo) {
tracing::error!("{:?}", Bar(foo))
}when the above code is compiled with the log feature enabled, you get the following compiler error:
error[E0382]: use of moved value: `foo`
--> src/lib.rs:8:33
|
7 | pub fn foo(foo: Foo) {
| --- move occurs because `foo` has type `Foo`, which does not implement the `Copy` trait
8 | tracing::error!("{:?}", Bar(foo))
| ^^^
| |
| value moved here
| value used here after move
For more information about this error, try `rustc --explain E0382`.
(You can also extend this to weird and wonderful effects, such as a counter that depends on the feature flags and log level.)
This error is confusing by itself, but is made worse by the fact that it can be triggered indirectly; this (A) compiles fine without the log feature enabled, but if a crate (B) depends on A and (even indirectly) enables the log feature then A will fail to compile as part of B, but will compile fine by itself.
From a quick code read I think there may be other macros affected by this, but I haven't investigated any further.