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:33d9e280:start=1541565257978533504,finish=1541565259031431238,duration=1052897734
$ 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
---
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[00:55:32] failures:
[00:55:32] 
[00:55:32] ---- [run-pass] run-pass/rfcs/rfc-2302-self-struct-ctor.rs stdout ----
[00:55:32] 
[00:55:32] error: test compilation failed although it shouldn't!
[00:55:32] status: exit code: 101
[00:55:32] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/run-pass/rfcs/rfc-2302-self-struct-ctor.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/run-pass/rfcs/rfc-2302-self-struct-ctor/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/run-pass/rfcs/rfc-2302-self-struct-ctor/auxiliary"
[00:55:32] ------------------------------------------
[00:55:32] 
[00:55:32] ------------------------------------------
[00:55:32] stderr:
[00:55:32] stderr:
[00:55:32] ------------------------------------------
[00:55:32] {"message":"librustc_typeck/check/_match.rs:820: unexpected pattern definition: SelfCtor(DefId(0/0:5 ~ rfc_2302_self_struct_ctor[317d]::{{impl}}[0]))","code":null,"level":"error: internal compiler error","spans":[],"children":[],"rendered":"error: internal compiler error: librustc_typeck/check/_match.rs:820: unexpected pattern definition: SelfCtor(DefId(0/0:5 ~ rfc_2302_self_struct_ctor[317d]::{{impl}}[0]))\n\n"}
[00:55:32] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[00:55:32] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[00:55:32] {"message":"aborting due to previous error","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to previous error\n\n"}
[00:55:32] note: the compiler unexpectedly panicked. this is a bug.
[00:55:32] 
[00:55:32] note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
[00:55:32] 
[00:55:32] 
[00:55:32] note: rustc 1.32.0-dev running on x86_64-unknown-linux-gnu
[00:55:32] 
[00:55:32] note: compiler flags: -Z ui-testing -Z unstable-options -C prefer-dynamic -C rpath
[00:55:32] 
[00:55:32] ------------------------------------------
[00:55:32] 
[00:55:32] thread '[run-pass] run-pass/rfcs/rfc-2302-self-struct-ctor.rs' panicked at 'explicit panic', tools/compiletest/src/runtest.rs:3284:9
---
[00:55:32] 
[00:55:32] thread 'main' panicked at 'Some tests failed', tools/compiletest/src/main.rs:503:22
[00:55:32] 
[00:55:32] 
[00:55:32] 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/run-pass" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "run-pass" "--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"
[00:55:32] 
[00:55:32] 
[00:55:32] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[00:55:32] Build completed unsuccessfully in 0:11:33
[00:55:32] Build completed unsuccessfully in 0:11:33
[00:55:32] make: *** [check] Error 1
[00:55:32] Makefile:58: recipe for target 'check' failed
2472692 ./obj
2459944 ./obj/build
1824164 ./obj/build/x86_64-unknown-linux-gnu
1069604 ./src
---
142868 ./obj/build/x86_64-unknown-linux-gnu/stage1-rustc
137084 ./obj/build/x86_64-unknown-linux-gnu/stage1-rustc/x86_64-unknown-linux-gnu
137080 ./obj/build/x86_64-unknown-linux-gnu/stage1-rustc/x86_64-unknown-linux-gnu/release
134668 ./obj/build/bootstrap/debug/incremental/bootstrap-zemjd6kcyh2u
134664 ./obj/build/bootstrap/debug/incremental/bootstrap-zemjd6kcyh2u/s-f6ftdb5ouf-1tnqsqn-22tmsi8iacpi9
130756 ./obj/build/x86_64-unknown-linux-gnu/stage0-bootstrap-tools/x86_64-unknown-linux-gnu
130752 ./obj/build/x86_64-unknown-linux-gnu/stage0-bootstrap-tools/x86_64-unknown-linux-gnu/release
123680 ./obj/build/x86_64-unknown-linux-gnu/stage0-bootstrap-tools/x86_64-unknown-linux-gnu/release/deps
111072 ./src/llvm/test/CodeGen
---
55856 ./obj/build/x86_64-unknown-linux-gnu/stage0-sysroot
55852 ./obj/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib
55848 ./obj/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib
55844 ./obj/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib/x86_64-unknown-linux-gnu
55840 ./obj/build/x86_64-unkno\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:019379a8
travis_time:start:019379a8
$ 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:08847b07
$ dmesg | grep -i kill

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[F001]

I used "force push" to update the merge request, see commit 2b41803. However, the Travis job seems not triggered.