Avoid panic when matching function call

[F001]

Fix #55718

This bug is introduced by #53751. The original code checked Def::AssociatedConst(..) | Def::Method(..) before pat_ty.no_bound_vars().expect("expected fn type"). But somehow I exchanged the sequence carelessly. Sorry about that.

r? @petrochenkov

[rust-highfive]

The job x86_64-gnu-llvm-5.0 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.

travis_time:end:0825434e:start=1541584237071019649,finish=1541584238040638110,duration=969618461
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#Pull-Requests-and-Security-Restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
Setting environment variables from .travis.yml
$ export IMAGE=x86_64-gnu-llvm-5.0
---
[00:50:11] diff of stderr:
[00:50:11] 
[00:50:11] 5    |         ^^^^^^^^^^^^^^^^ not a tuple variant or struct
[00:50:11] 6 
[00:50:11] 7 error[E0164]: expected tuple struct/variant, found method `<Path>::new`
[00:50:11] -   --> $DIR/match-fn-call.rs:7:9
[00:50:11] +   --> $DIR/match-fn-call.rs:8:9
[00:50:11] 9    |
[00:50:11] 10 LL |         Path::new("bar"ch foo {\n        Foo::B(i) => i, // error E0164\n    }\n}\n```\n\nTry using `{}` instead:\n\n```\nenum Foo { B { i: u32 } }\n\nfn bar(foo: Foo) -> u32 {\n    match foo {\n        Foo::B{i} => i,\n    }\n}\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/match/match-fn-call.rs","byte_start":92,"byte_end":108,"line_start":6,"line_end":6,"column_start":9,"column_end":25,"is_primary":true,"text":[{"text":"        Path::new(\"foo\") => println!(\"foo\"),","highlight_start":9,"highlight_end":25}],"label":"not a tuple variant or struct","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0164]: expected tuple struct/variant, found method `<Path>::new`\n  --> /checkout/src/test/ui/match/match-fn-call.rs:6:9\n   |\nLL |         Path::new(\"foo\") => println!(\"foo\"),\n   |         ^^^^^^^^^^^^^^^^ not a tuple variant or struct\n\n"}
[00:50:11] {"message":"expected tuple struct/variant, found method `<Path>::new`","code":{"code":"E0164","explanation":"\nThis error means that an attempt was made to match a struct type enum\nvariant as a non-struct type:\n\n```compile_fail,E0164\nenum Foo { B { i: u32 } }\n\nfn bar(foo: Foo) -> u32 {\n    match foo {\n        Foo::B(i) => i, // error E0164\n    }\n}\n```\n\nTry using `{}` instead:\n\n```\nenum Foo { B { i: u32 } }\n\nfn bar(foo: Foo) -> u32 {\n    match foo {\n        Foo::B{i} => i,\n    }\n}\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/match/match-fn-call.rs","byte_start":186,"byte_end":202,"line_start":8,"line_end":8,"column_start":9,"column_end":25,"is_primary":true,"text":[{"text":"        Path::new(\"bar\") => println!(\"bar\"),","highlight_start":9,"highlight_end":25}],"label":"not a tuple variant or struct","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0164]: expected tuple struct/variant, found method `<Path>::new`\n  --> /checkout/src/test/ui/match/match-fn-call.rs:8:9\n   |\nLL |         Path::new(\"bar\") => println!(\"bar\"),\n   |         ^^^^^^^^^^^^^^^^ not a tuple variant or struct\n\n"}
[00:50:11] {"message":"aborting due to 2 previous errors","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 2 previous errors\n\n"}
[00:50:11] {"message":"For more information about this error, try `rustc --explain E0164`.","code":null,"level":"","spans":[],"children":[],"rendered":"For more information about this error, try `rustc --explain E0164`.\n"}
[00:50:11] ------------------------------------------
[00:50:11] 
[00:50:11] thread '[ui] ui/match/match-fn-call.rs' panicked at 'explicit panic', tools/compiletest/src/runtest.rs:3284:9
[00:50:11] note: Run with `RUST_BACKTRACE=1` for a backtrace.
---
[00:50:11] 
[00:50:11] thread 'main' panicked at 'Some tests failed', tools/compiletest/src/main.rs:503:22
[00:50:11] 
[00:50:11] 
[00:50:11] 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" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-5.0/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Zunstable-options " "--target-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-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" "5.0.0\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[00:50:11] 
[00:50:11] 
[00:50:11] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[00:50:11] Build completed unsuccessfully in 0:03:36
[00:50:11] Build completed unsuccessfully in 0:03:36
[00:50:11] Makefile:58: recipe for target 'check' failed
[00:50:11] make: *** [check] Error 1

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:0ae85410
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date4193592 .
---
travis_time:end:1e838182:start=1541587260227360118,finish=1541587260232668775,duration=5308657
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:213653b4
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:2740f640
travis_time:start:2740f640
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:1cad264c
$ dmesg | grep -i kill

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)

[petrochenkov]

@bors r+
Thanks!

[bors]

📌 Commit f63c2f8 has been approved by petrochenkov

[Mark-Simulacrum]

@bors rollup

[nikomatsakis]

Approving for beta because (a) small patch and (b) tight timeline for beta.

cc @rust-lang/community

[pietroalbini]

Did you mean to cc @rust-lang/compiler?