Unify wording of resolve error

[estebank]

Remove "failed to resolve" from the main error message and use the same format we use in other resolution errors "cannot find name":

error[E0433]: cannot find `nonexistent` in `existent`
  --> $DIR/custom_attr_multisegment_error.rs:5:13
   |
LL | #[existent::nonexistent]
   |             ^^^^^^^^^^^ could not find `nonexistent` in `existent`

The intent behind this is to end up with all resolve errors eventually be on the form of

error[ECODE]: cannot find `{NAME}` in {SCOPE}
  --> $DIR/file.rs:5:13
   |
LL | #[existent::nonexistent]
   |             ^^^^^^^^^^^ {SPECIFIC LABEL}

A category of errors that is interest are those that involve keywords. For example:

error[E0433]: cannot find `Self` in this scope
  --> $DIR/issue-97194.rs:2:35
   |
LL |     fn bget(&self, index: [usize; Self::DIM]) -> bool {
   |                                   ^^^^ `Self` is only available in impls, traits, and type definitions

and

error[E0433]: cannot find `super` in this scope
  --> $DIR/keyword-super.rs:2:9
   |
LL |     let super: isize;
   |         ^^^^^ there are too many leading `super` keywords

For these the label provides the actual help, while the message is less informative beyond telling you "couldn't find name".

This is an off-shoot of #126810 and #128086, a subset of the intended changes there with review comments applied.

r? @petrochenkov

[rustbot]

This PR modifies tests/ui/issues/. If this PR is adding new tests to tests/ui/issues/,
please refrain from doing so, and instead add it to more descriptive subdirectories.

[estebank]

This is a diagnostic that needs improvement regardless: we need to explain that Foo is a type and that macros can't be in them. It would be particularly bad if Foo had an associated item bar as well.

[estebank]

Changed the output to be

error[E0433]: cannot find macro `bar` in enum `Foo`
  --> $DIR/extern-macro.rs:5:13
   |
LL |     let _ = Foo::bar!();
   |             ^^^^^^^^ a macro can't exist within an enum

Not perfect, but I feel it's more informative than we used to be.

[estebank]

Ah, I found I'd opened a separate PR already with some of these changes, and you had a comment about this change in particular

#128086 (comment)

I agree that this isn't an improvement, but the primary label does still mention the intended issue. I'll see over the weekend what I can do about this.

[estebank]

Let me know if there's a wording you'd prefer for the label. I want to communicate the impossibility of the macro being in ADTs and traits in the first place.

[rust-log-analyzer]

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

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

tests/fail/tree_borrows/reserved/int-protected-write.rs ... ok
tests/fail/weak_memory/weak_uninit.rs ... ok

FAILED TEST: tests/fail/rustc-error2.rs
command: MIRI_ENV_VAR_TEST="0" MIRI_TEMP="/tmp/miri-uitest-VoPGws" RUST_BACKTRACE="1" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/miri" "--error-format=json" "--sysroot=/checkout/obj/build/x86_64-unknown-linux-gnu/miri-sysroot" "-Dwarnings" "-Dunused" "-Ainternal_features" "-Zui-testing" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/tmp/miri_ui/0/tests/fail" "tests/fail/rustc-error2.rs" "--edition" "2021"

error: actual output differed from expected
Execute `./miri test --bless` to update `tests/fail/rustc-error2.stderr` to the actual output
--- tests/fail/rustc-error2.stderr
+++ <stderr output>
---
Location:
   /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ui_test-0.30.2/src/lib.rs:365

  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BACKTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   1: <color_eyre[5a00b443e1703d9a]::config::EyreHook>::into_eyre_hook::{closure#0}<unknown>
      at <unknown source file>:<unknown line>
   2: eyre[d9b0c1a323608d26]::private::format_err<unknown>
      at <unknown source file>:<unknown line>
   3: ui_test[ff0811f2fc4ba226]::run_tests_generic::<ui_test[ff0811f2fc4ba226]::default_file_filter, ui[ec7046a92c176db1]::run_tests::{closure#1}, alloc[3d295bdc4298664f]::boxed::Box<dyn ui_test[ff0811f2fc4ba226]::status_emitter::StatusEmitter>><unknown>
      at <unknown source file>:<unknown line>
   4: ui[ec7046a92c176db1]::ui<unknown>
      at <unknown source file>:<unknown line>
   5: ui[ec7046a92c176db1]::main<unknown>
      at <unknown source file>:<unknown line>
   6: std[b7b9f6e5c8de3bba]::sys::backtrace::__rust_begin_short_backtrace::<fn() -> core[69aab6a1f1fdf15a]::result::Result<(), eyre[d9b0c1a323608d26]::Report>, core[69aab6a1f1fdf15a]::result::Result<(), eyre[d9b0c1a323608d26]::Report>><unknown>
      at <unknown source file>:<unknown line>
   7: std[b7b9f6e5c8de3bba]::rt::lang_start::<core[69aab6a1f1fdf15a]::result::Result<(), eyre[d9b0c1a323608d26]::Report>>::{closure#0}<unknown>
      at <unknown source file>:<unknown line>
   8: std[b7b9f6e5c8de3bba]::rt::lang_start_internal<unknown>
      at <unknown source file>:<unknown line>
   9: main<unknown>
      at <unknown source file>:<unknown line>
  10: __libc_start_main<unknown>
      at <unknown source file>:<unknown line>
  11: _start<unknown>
      at <unknown source file>:<unknown line>

Run with COLORBT_SHOW_HIDDEN=1 environment variable to disable frame filtering.
Run with RUST_BACKTRACE=full to include source snippets.
error: test failed, to rerun pass `--test ui`

Caused by:
  process didn't exit successfully: `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/ui-de637b1a885c82e4` (exit status: 1)
Command `/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo test --target x86_64-unknown-linux-gnu -Zbinary-dep-depinfo -j 4 -Zroot-dir=/checkout --locked --color always --release --manifest-path /checkout/src/tools/miri/Cargo.toml -- [workdir=/checkout]` failed with exit code 1
Created at: src/bootstrap/src/core/builder/cargo.rs:423:33
Executed at: src/bootstrap/src/core/build_steps/test.rs:644:19

Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:39:59
  local time: Sat Aug 16 20:02:28 UTC 2025
  network time: Sat, 16 Aug 2025 20:02:28 GMT
##[error]Process completed with exit code 1.
Post job cleanup.