Improve unknown external crate error

[rylev]

This improves error messages when unknown items in the crate root are encountered.

Fixes#63799

r? @estebank

[rust-log-analyzer]

The job mingw-check failed! Check out the build log: (web)(plain)

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

configure: rust.channel := nightly
configure: rust.debug-assertions := True
configure: llvm.assertions := True
configure: dist.missing-tools := True
configure: build.configure-args := ['--enable-sccache', '--disable-manage-submodu ...
configure: writing `config.toml` in current directory
configure: configure: run `python /checkout/x.py --help`
configure: ---
skip untracked path src/llvm-project/ during rustfmt invocations
Diff in /checkout/compiler/rustc_resolve/src/lib.rs at line 2459:
}
} else {
let parent = path[i - 1].ident.name;
- let parent =
- if parent == kw::PathRoot { "crate root".to_owned() } else { format!("`{}`", parent) };
+ let parent = if parent == kw::PathRoot {
+ "crate root".to_owned()
+ } else {
+ format!("`{}`", parent)
let mut msg = format!("could not find `{}` in {}", ident, parent);
Running `"/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/rustfmt" "--config-path" "/checkout" "--edition" "2018" "--unstable-features" "--skip-children" "--check" "/checkout/compiler/rustc_resolve/src/lib.rs"` failed.
If you're running `tidy`, try again with `--bless`. Or, if you just want to format code, run `./x.py fmt` instead.
if ns == TypeNS || ns == ValueNS {
Build completed unsuccessfully in 0:00:15

[rust-log-analyzer]

The job x86_64-gnu-llvm-9 failed! Check out the build log: (web)(plain)

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

---- [ui] ui/issues/issue-71406.rs stdout ----
diff of stderr:
- error[E0433]: failed to resolve: expected type, found function `channel` in `mpsc`
+ error[E0433]: failed to resolve: expected type, found function `channel` in ``mpsc``
3 |
3 |
4 LL | let (tx, rx) = mpsc::channel::new(1);
- | ^^^^^^^ expected type, found function `channel` in `mpsc`
+ | ^^^^^^^ expected type, found function `channel` in ``mpsc``
7 error: aborting due to previous error
8 The actual stderr differed from the expected stderr.
Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/issues/issue-71406/issue-71406.stderr
To update references, rerun the tests and pass the `--bless` flag
To only update this specific test, also pass `--test-args issues/issue-71406.rs`
error: 1 errors occurred comparing output.
status: exit code: 1
status: exit code: 1
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/issues/issue-71406.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zemit-future-incompat-report" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/issues/issue-71406" "-A" "unused" "-Crpath" "-O" "-Cdebuginfo=0" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/issues/issue-71406/auxiliary"
------------------------------------------
------------------------------------------
stderr:
stderr:
------------------------------------------
error[E0433]: failed to resolve: expected type, found function `channel` in ``mpsc``
|
|
LL | let (tx, rx) = mpsc::channel::new(1);
| ^^^^^^^ expected type, found function `channel` in ``mpsc``
error: aborting due to previous error
For more information about this error, try `rustc --explain E0433`.
---
Some tests failed in compiletest suite=ui mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--suite" "ui" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-9/bin/FileCheck" "--nodejs" "/usr/bin/node" "--host-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python3" "--lldb-python" "/usr/bin/python3" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "9.0.0" "--llvm-components" "aarch64 aarch64asmparser aarch64codegen aarch64desc aarch64disassembler aarch64info aarch64utils aggressiveinstcombine all all-targets amdgpu amdgpuasmparser amdgpucodegen amdgpudesc amdgpudisassembler amdgpuinfo amdgpuutils analysis arm armasmparser armcodegen armdesc armdisassembler arminfo armutils asmparser asmprinter avr avrasmparser avrcodegen avrdesc avrdisassembler avrinfo binaryformat bitreader bitstreamreader bitwriter bpf bpfasmparser bpfcodegen bpfdesc bpfdisassembler bpfinfo codegen core coroutines coverage debuginfocodeview debuginfodwarf debuginfogsym debuginfomsf debuginfopdb demangle dlltooldriver engine executionengine fuzzmutate globalisel hexagon hexagonasmparser hexagoncodegen hexagondesc hexagondisassembler hexagoninfo instcombine instrumentation interpreter ipo irreader jitlink lanai lanaiasmparser lanaicodegen lanaidesc lanaidisassembler lanaiinfo libdriver lineeditor linker lto mc mca mcdisassembler mcjit mcparser mips mipsasmparser mipscodegen mipsdesc mipsdisassembler mipsinfo mirparser msp430 msp430asmparser msp430codegen msp430desc msp430disassembler msp430info native nativecodegen nvptx nvptxcodegen nvptxdesc nvptxinfo objcarcopts object objectyaml option orcjit passes perfjitevents powerpc powerpcasmparser powerpccodegen powerpcdesc powerpcdisassembler powerpcinfo profiledata remarks riscv riscvasmparser riscvcodegen riscvdesc riscvdisassembler riscvinfo riscvutils runtimedyld scalaropts selectiondag sparc sparcasmparser sparccodegen sparcdesc sparcdisassembler sparcinfo support symbolize systemz systemzasmparser systemzcodegen systemzdesc systemzdisassembler systemzinfo tablegen target textapi transformutils vectorize webassembly webassemblyasmparser webassemblycodegen webassemblydesc webassemblydisassembler webassemblyinfo windowsmanifest x86 x86asmparser x86codegen x86desc x86disassembler x86info x86utils xcore xcorecodegen xcoredesc xcoredisassembler xcoreinfo xray" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
failed to run: /checkout/obj/build/bootstrap/debug/bootstrap --stage 2 test --exclude src/tools/tidy
Build completed unsuccessfully in 0:17:48

[jyn514]

Rather than special casing this here, does it make sense to change in impl Display for Symbol instead? Then you don't have to worry about missing it somewhere (and everyone else using this benefits as well).

[rylev]

This is certainly a possibility. I didn't do this because I was unsure of the ramifications of renaming the symbol's string representation (particularly around json serialization/deserialization). The change I made seems to be the central place for diagnostics around path resolution (i.e., there are not UI tests that still reference {{root}}).

[estebank]

Should it be root crate instead?

[rylev]

Hmmm, the path root is normally referred to as the crate root as you can see here. root crate makes it sound like this refers to a crate itself but it does not, it's the root of the namespace hierarchy.

[estebank]

@bors r+ rollup

[bors]

📌 Commit 38b7742 has been approved by estebank