impl Trait diagnostic/test cleanups

[oli-obk]

No description provided.

[rust-highfive]

r? @estebank

(rust_highfive has picked a reviewer for you, use r? to override)

[rust-highfive]

The job x86_64-gnu-llvm-3.9 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:43:24] ....................................................................................................
[00:43:27] ....................................................................................................
[00:43:31] ....................................................................................................
[00:43:34] ....................................................................................................
[00:43:39] ...............................................F....................................................
[00:43:48] ....................................................................................................
[00:43:53] ......................................................................i.............................
[00:43:58] ...............................................i....................................................
[00:44:02] ...................................................................ii...............................
---
[00:44:16] thread 'main' panicked at 'Some tests failed', tools/compiletest/src/main.rs:498:22
[00:44:16] ---- [ui] ui/impl-trait/impl-generic-mismatch.rs stdout ----
[00:44:16] diff of stderr:
[00:44:16] 
[00:44:16] 34 LL |     fn hash(&self, hasher: &mut impl Hasher) {}
[00:44:16] 35    |                                 ^^^^^^^^^^^ expected generic parameter, found `impl Trait`
[00:44:16] 36    | 
[00:44:16] -   ::: /home/oliver/Projects/rust/rust3/src/libcore/hash/mod.rs:185:13
[00:44:16] +   ::: /checkout/src/libcore/hash/mod.rs:185:13
[00:44:16] 38    |
[00:44:16] 39 LL |     fn hash<H: Hasher>(&self, state: &mut H);
[00:44:16] 40    |             - declaration in trait here
[00:44:16] 
[00:44:16] The actual stderr differed from the expected stderr.
[00:44:16] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/impl-generic-mismatch/impl-generic-mismatch.stderr
[00:44:16] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/impl-generic-mismatch/impl-generic-mismatch.stderr
[00:44:16] To update references, rerun the tests and pass the `--bless` flag
[00:44:16] To only update this specific test, also pass `--test-args impl-trait/impl-generic-mismatch.rs`
[00:44:16] error: 1 errors occurred comparing output.
[00:44:16] status: exit code: 101
[00:44:16] status: exit code: 101
[00:44:16] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/impl-generic-mismatch/a" "-Crpath" "-O" "-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/impl-trait/impl-generic-mismatch/auxiliary" "-A" "unused"
[00:44:16] ------------------------------------------
[00:44:16] 
[00:44:16] ------------------------------------------
[00:44:16] stderr:
[00:44:16] stderr:
[00:44:16] ------------------------------------------
[00:44:16] {"message":"method `foo` has incompatible signature for trait","code":{"code":"E0643","explanation":"\nThis error indicates that there is a mismatch between generic parameters and\nimpl Trait parameters in a trait declaration versus its impl.\n\n```compile_fail,E0643\ntrait Foo {\n    fn foo(&self, _: &impl Iterator);\n}\nimpl Foo for () {\n    fn foo<U: Iterator>(&self, _: &U) { } // error method `foo` has incompatible\n                                          // signature for trait\n}\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":523,"byte_end":533,"line_start":14,"line_end":14,"column_start":23,"column_end":33,"is_primary":false,"text":[{"text":"    fn foo(&self, _: &impl Debug);","highlight_start":23,"highlight_end":33}],"label":"declaration in trait here","suggested_replacement":null,"expansion":null},{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":568,"byte_end":569,"line_start":18,"line_end":18,"column_start":12,"column_end":13,"is_primary":true,"text":[{"text":"    fn foo<U: Debug>(&self, _: &U) { }","highlight_start":12,"highlight_end":13}],"label":"expected `impl Trait`, found generic parameter","suggested_replacement":null,"expansion":null}],"children":[{"message":"try removing the generic parameter and using `impl Trait` instead","code":null,"level":"help","spans":[{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":567,"byte_end":577,"line_start":18,"line_end":18,"column_start":11,"column_end":21,"is_primary":true,"text":[{"text":"    fn foo<U: Debug>(&self, _: &U) { }","highlight_start":11,"highlight_end":21}],"label":null,"suggested_replacement":"","expansion":null},{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":589,"byte_end":590,"line_start":18,"line_end":18,"column_start":33,"column_end":34,"is_primary":true,"text":[{"text":"    fn foo<U: Debug>(&self, _: &U) { }","highlight_start":33,"highlight_end":34}],"label":null,"suggested_replacement":"impl Debug","expansion":null}],"children":[],"rendered":null}],"rendered":"error[E0643]: method `foo` has incompatible signature for trait\n  --> /checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs:18:12\n   |\nLL |     fn foo(&self, _: &impl Debug);\n   |                       ---------- declaration in trait here\n...\nLL |     fn foo<U: Debug>(&self, _: &U) { }\n   |            ^ expected `impl Trait`, found generic parameter\nhelp: try removing the generic parameter and using `impl Trait` instead\n   |\nLL |     fn foo(&self, _: &impl Debug) { }\n   |\n\n"}
[00:44:16] {"message":"method `bar` has incompatible signature for trait","code":{"code":"E0643","explanation":"\nThis error indicates that there is a mismatch between generic parameters and\nimpl Trait parameters in a trait declaration versus its impl.\n\n```compile_fail,E0643\ntrait Foo {\n    fn foo(&self, _: &impl Iterator);\n}\nimpl Foo for () {\n    fn foo<U: Iterator>(&self, _: &U) { } // error method `foo` has incompatible\n                                          // signature for trait\n}\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":687,"byte_end":688,"line_start":23,"line_end":23,"column_start":12,"column_end":13,"is_primary":false,"text":[{"text":"    fn bar<U: Debug>(&self, _: &U);","highlight_start":12,"highlight_end":13}],"label":"declaration in trait here","suggested_replacement":null,"expansion":null},{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":755,"byte_end":765,"line_start":27,"line_end":27,"column_start":23,"column_end":33,"is_primary":true,"text":[{"text":"    fn bar(&self, _: &impl Debug) { }","highlight_start":23,"highlight_end":33}],"label":"expected generic parameter, found `impl Trait`","suggested_replacement":null,"expansion":null}],"children":[{"message":"try changing the `impl Trait` argument to a generic parameter","code":null,"level":"help","spans":[{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":755,"byte_end":765,"line_start":27,"line_end":27,"column_start":23,"column_end":33,"is_primary":true,"text":[{"text":"    fn bar(&self, _: &impl Debug) { }","highlight_start":23,"highlight_end":33}],"label":null,"suggested_replacement":"U","expansion":null},{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":686,"byte_end":686,"line_start":23,"line_end":23,"column_start":11,"column_end":11,"is_primary":true,"text":[{"text":"    fn bar<U: Debug>(&self, _: &U);","highlight_start":11,"highlight_end":11}],"label":null,"suggested_replacement":"<U: Debug>","expansion":null}],"children":[],"rendered":null}],"rendered":"error[E0643]: method `bar` has incompatible signature for trait\n  --> /checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs:27:23\n   |\nLL |     fn bar<U: Debug>(&self, _: &U);\n   |            - declaration in trait here\n...\nLL |     fn bar(&self, _: &impl Debug) { }\n   |                       ^^^^^^^^^^ expected generic parameter, found `impl Trait`\nhelp: try changing the `impl Trait` argument to a generic parameter\n   |\nLL |     fn bar<U: Debug><U: Debug>(&self, _: &U);\nLL | }\nLL | \nLL | impl Bar for () {\nLL |     fn bar(&self, _: &U) { }\n   |\n\n"}
[00:44:16] {"message":"method `hash` has incompatible signature for trait","code":{"code":"E0643","explanation":"\nThis error indicates that there is a mismatch between generic parameters and\nimpl Trait parameters in a trait declaration versus its impl.\n\n```compile_fail,E0643\ntrait Foo {\n    fn foo(&self, _: &impl Iterator);\n}\nimpl Foo for () {\n    fn foo<U: Iterator>(&self, _: &U) { } // error method `foo` has incompatible\n                                          // signature for trait\n}\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/libcore/hash/mod.rs","byte_start":4730,"byte_end":4731,"line_start":185,"line_end":185,"column_start":13,"column_end":14,"is_primary":false,"text":[{"text":"    fn hash<H: Hasher>(&self, state: &mut H);","highlight_start":13,"highlight_end":14}],"label":"declaration in trait here","suggested_replacement":null,"expansion":null},{"file_name":"/checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs","byte_start":967,"byte_end":978,"line_start":38,"line_end":38,"column_start":33,"column_end":44,"is_primary":true,"text":[{"text":"    fn hash(&self, hasher: &mut impl Hasher) {}","highlight_start":33,"highlight_end":44}],"label":"expected generic parameter, found `impl Trait`","suggested_replacement":null,"expansion":null}],"children":[],"rendered":"error[E0643]: method `hash` has incompatible signature for trait\n  --> /checkout/src/test/ui/impl-trait/impl-generic-mismatch.rs:38:33\n   |\nLL |     fn hash(&self, hasher: &mut impl Hasher) {}\n   |                                 ^^^^^^^^^^^ expected generic parameter, found `impl Trait`\n   | \n  ::: /checkout/src/libcore/hash/mod.rs:185:13\n   |\nLL |     fn hash<H: Hasher>(&self, state: &mut H);\n   |             - declaration in trait here\n\n"}
[00:44:16] {"message":"aborting due to 3 previous errors","code":null,"level":"error","spans":[],"children":[],"rendere-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "3.9.1\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[00:44:16] 
[00:44:16] 
[00:44:16] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[00:44:16] Build completed unsuccessfully in 0:02:14
[00:44:16] Build completed unsuccessfully in 0:02:14
[00:44:16] make: *** [check] Error 1
[00:44:16] Makefile:58: recipe for target 'check' failed

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:0480a4ca
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[oli-obk]

O_o --bless seems to be exposing local paths?

[oli-obk]

Ah no. This is because it's a path into the libstd.

[oli-obk]

I adjusted compiletest to also normalize paths into the libstd/libcore

[estebank]

Love it!

[estebank]

Incorrect span for the suggestion. This should be in the bar for the impl Bar for ()

[estebank]

Use impl_span here instead and the output will be correct.

This is because generate_fn_name_span looks backwards until it finds fn in the span, instead of checking wether the span starts with fn<WS>. When using impl_m.span, this starts in the fn..., so it goes backwards until it finds the previous piece of code that contains fn, which in this case is the trait's method. Using impl_span will break if any part of the snippet contains fn (like a method called my_fn).

In order to avoid this there are two options: changing generate_fn_name_span to peek at the first three chars of the passed span's snippet to see if the first two are fn and the third is whitespace, and if so assign span to prev_span and use _impl_m_span here instead, or synthesize a new span derived from _impl_m_span moving forward long enough to leave the fn<WS> outside of the new span. Either way, it would have to account for the potential leading whitespace and visibility (pub(crate), etc) text.

We really need to add spans to all idents, IMO. We keep having to do this kind of brittle span wrangling way too often.

[estebank]

@bors r+

@oli-obk approving even though there's an incorrect suggestion. I can fix it as soon as it gets merged, but if you'll have the time to do it yourself, go ahead and stop bors from merging.

[bors]

📌 Commit 849c565 has been approved by estebank

[bors]

⌛ Testing commit 849c565 with merge b4463d7...

[oli-obk]

I was debugging this yesterday, but didn't get very far. I think the suggestion is correct, the issue is the renderer. We should probably make it a rustfix test so we can see the fixed output

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: estebank
Pushing b4463d7 to master...