fix ItemKind::DefaultImpl doc comment

[durka]

Upgrade comment to doc comment.

...Is this actually used? If so, why does the Impl variant right below have a Defaultness?

[rust-highfive]

r? @pnkfelix

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[durka]

I realized DefaultImpl has nothing to do with default impl and is rather about auto traits.

[arielb1]

@bors r+ rollup

[bors]

📌 Commit fc5e8dc has been approved by arielb1

[bors]

⌛ Testing commit fc5e8dc with merge 0e6a277caf99eddd100a6cfd58fdf7d20dd6e309...

[bors]

💔 Test failed - status-appveyor

[kennytm]

@bors retry #43402

[01:18:08] ---- [run-make] run-make\issue-26092 stdout ----
[01:18:08] 	
[01:18:08] error: make failed
[01:18:08] status: exit code: 2
[01:18:08] command: "make"
[01:18:08] stdout:
[01:18:08] ------------------------------------------
[01:18:08] PATH="/c/projects/rust/build/x86_64-pc-windows-gnu/test/run-make/issue-26092.stage2-x86_64-pc-windows-gnu:C:\projects\rust\build\x86_64-pc-windows-gnu\stage2\bin:/c/projects/rust/build/x86_64-pc-windows-gnu/stage0-tools/x86_64-pc-windows-gnu/release/deps:/c/projects/rust/build/x86_64-pc-windows-gnu/stage0-sysroot/lib/rustlib/x86_64-pc-windows-gnu/lib:/c/Program Files (x86)/Inno Setup 5:/c/Python27:/c/projects/rust/mingw64/bin:/usr/bin:/c/Perl/site/bin:/c/Perl/bin:/c/Windows/system32:/c/Windows:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0:/c/Program Files/7-Zip:/c/Program Files/Microsoft/Web Platform Installer:/c/Tools/GitVersion:/c/Tools/PsTools:/c/Program Files/Git LFS:/c/Program Files (x86)/Subversion/bin:/c/Program Files/Microsoft SQL Server/120/Tools/Binn:/c/Program Files/Microsoft SQL Server/Client SDK/ODBC/110/Tools/Binn:/c/Program Files (x86)/Microsoft SQL Server/120/Tools/Binn:/c/Program Files/Microsoft SQL Server/120/DTS/Binn:/c/Program Files (x86)/Microsoft SQL Server/120/Tools/Binn/ManagementStudio:/c/Tools/WebDriver:/c/Program Files (x86)/Microsoft SDKs/TypeScript/1.4:/c/Program Files (x86)/Microsoft Visual Studio 12.0/Common7/IDE/PrivateAssemblies:/c/Program Files (x86)/Microsoft SDKs/Azure/CLI/wbin:/c/Ruby193/bin:/c/Tools/NUnit/bin:/c/Tools/xUnit:/c/Tools/MSpec:/c/Tools/Coverity/bin:/c/Program Files (x86)/CMake/bin:/c/go/bin:/c/Program Files/Java/jdk1.8.0/bin:/c/Python27:/c/Program Files/nodejs:/c/Program Files (x86)/iojs:/c/Program Files/iojs:/c/Users/appveyor/AppData/Roaming/npm:/c/Program Files/Microsoft SQL Server/130/Tools/Binn:/c/Program Files (x86)/MSBuild/14.0/Bin:/c/Tools/NuGet:/c/Program Files (x86)/Microsoft Visual Studio 14.0/Common7/IDE/CommonExtensions/Microsoft/TestWindow:/c/Program Files/Microsoft DNX/Dnvm:/c/Program Files/Microsoft SQL Server/Client SDK/ODBC/130/Tools/Binn:/c/Program Files (x86)/Microsoft SQL Server/130/Tools/Binn:/c/Program Files (x86)/Microsoft SQL Server/130/DTS/Binn:/c/Program Files/Microsoft SQL Server/130/DTS/Binn:/c/Program Files (x86)/Microsoft SQL Server/110/DTS/Binn:/c/Program Files (x86)/Microsoft SQL Server/120/DTS/Binn:/c/Program Files (x86)/Apache/Maven/bin:/c/Python27/Scripts:/c/Tools/NUnit3:/c/Program Files/Mercurial:/c/Program Files/LLVM/bin:/c/Program Files/dotnet:/c/Program Files/erl8.3/bin:/c/Tools/curl/bin:/c/Program Files/Amazon/AWSCLI:/c/Program Files (x86)/Microsoft SQL Server/140/DTS/Binn:/c/Program Files (x86)/Microsoft Visual Studio 14.0/Common7/IDE/Extensions/Microsoft/SQLDB/DAC/140:/c/Program Files (x86)/Yarn/bin:/c/Program Files/Git/cmd:/c/Program Files/Git/usr/bin:/c/ProgramData/chocolatey/bin:/c/Tools/vcpkg:/c/Program Files (x86)/nodejs:/c/Program Files/Microsoft Service Fabric/bin/Fabric/Fabric.Code:/c/Program Files/Microsoft SDKs/Service Fabric/Tools/ServiceFabricLocalClusterManager:/c/Users/appveyor/AppData/Local/Yarn/bin:/c/Users/appveyor/AppData/Roaming/npm:/c/Program Files/AppVeyor/BuildAgent:/c/projects/rust:/c/projects/rust/handle" 'C:\projects\rust\build\x86_64-pc-windows-gnu\stage2\bin\rustc.exe' --out-dir /c/projects/rust/build/x86_64-pc-windows-gnu/test/run-make/issue-26092.stage2-x86_64-pc-windows-gnu -L /c/projects/rust/build/x86_64-pc-windows-gnu/test/run-make/issue-26092.stage2-x86_64-pc-windows-gnu  -o "" blank.rs 2>&1 | \
[01:18:08] 		grep -i 'No such file or directory'
[01:18:08] 
[01:18:08] ------------------------------------------
[01:18:08] stderr:
[01:18:08] ------------------------------------------
[01:18:08] make: *** [Makefile:4: all] Error 1
[01:18:08] 
[01:18:08] ------------------------------------------
[01:18:08] 
[01:18:08] thread '[run-make] run-make\issue-26092' panicked at 'explicit panic', src\tools\compiletest\src\runtest.rs:2433:8
[01:18:08] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[01:18:08] 
[01:18:08] 
[01:18:08] failures:
[01:18:08]     [run-make] run-make\issue-26092
[01:18:08] 
[01:18:08] test result: FAILED. 160 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out
[01:18:08] 
[01:18:08] thread 'main' panicked at 'Some tests failed', src\tools\compiletest\src\main.rs:323:21
[01:18:08] 
[01:18:08] 
[01:18:08] command did not execute successfully: "C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\stage0-tools\\x86_64-pc-windows-gnu\\release\\compiletest.exe" "--compile-lib-path" "C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\stage2\\bin" "--run-lib-path" "C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\stage2\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "--rustc-path" "C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\stage2\\bin\\rustc.exe" "--rustdoc-path" "C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\stage2\\bin\\rustdoc.exe" "--src-base" "C:\\projects\\rust\\src/test\\run-make" "--build-base" "C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\test\\run-make" "--stage-id" "stage2-x86_64-pc-windows-gnu" "--mode" "run-make" "--target" "x86_64-pc-windows-gnu" "--host" "x86_64-pc-windows-gnu" "--llvm-filecheck" "C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\llvm\\build\\bin\\FileCheck.exe" "--nodejs" "C:\\Program Files (x86)\\nodejs\\node" "--host-rustcflags" "-Crpath -O" "--target-rustcflags" "-Crpath -O -Lnative=C:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\native\\rust-test-helpers" "--docck-python" "C:\\Python27\\python.exe" "--lldb-python" "C:\\Python27\\python.exe" "--gdb" "C:\\projects\\rust\\mingw64\\bin\\gdb" "--llvm-version" "4.0.1\n" "--cc" "gcc.exe" "--cxx" "g++.exe" "--cflags" "-ffunction-sections -fdata-sections -m64" "--llvm-components" "aarch64 aarch64asmparser aarch64asmprinter aarch64codegen aarch64desc aarch64disassembler aarch64info aarch64utils all all-targets analysis arm armasmparser armasmprinter armcodegen armdesc armdisassembler arminfo asmparser asmprinter bitreader bitwriter codegen core coroutines coverage debuginfocodeview debuginfodwarf debuginfomsf debuginfopdb demangle engine executionengine globalisel hexagon hexagonasmparser hexagoncodegen hexagondesc hexagondisassembler hexagoninfo instcombine instrumentation interpreter ipo irreader jsbackend jsbackendcodegen jsbackenddesc jsbackendinfo libdriver lineeditor linker lto mc mcdisassembler mcjit mcparser mips mipsasmparser mipsasmprinter mipscodegen mipsdesc mipsdisassembler mipsinfo mirparser msp430 msp430asmprinter msp430codegen msp430desc msp430info native nativecodegen nvptx nvptxasmprinter nvptxcodegen nvptxdesc nvptxinfo objcarcopts object objectyaml option orcjit passes pnacltransforms powerpc powerpcasmparser powerpcasmprinter powerpccodegen powerpcdesc powerpcdisassembler powerpcinfo profiledata runtimedyld scalaropts selectiondag sparc sparcasmparser sparcasmprinter sparccodegen sparcdesc sparcdisassembler sparcinfo support symbolize systemz systemzasmparser systemzasmprinter systemzcodegen systemzdesc systemzdisassembler systemzinfo tablegen target transformutils vectorize x86 x86asmparser x86asmprinter x86codegen x86desc x86disassembler x86info x86utils" "--llvm-cxxflags" "-IC:\\projects\\rust\\build\\x86_64-pc-windows-gnu\\llvm/include -ffunction-sections -fdata-sections -m64 -Wa,-mbig-obj -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wno-maybe-uninitialized -Wdelete-non-virtual-dtor -Wno-comment -Werror=date-time -std=gnu++11  -O2   -fno-exceptions -fno-rtti -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[01:18:08] expected success, got: exit code: 101