Arbitrary inner type in named impl key #6859

Job	Run time
WebAssembly	30s
pre_ci / pre_ci	2s
Outdated	0s
Bazel on ${{ matrix.os == 'ubuntu' && 'Linux' \|\| matrix.os == 'macos' && 'macOS' \|\| matrix.os == 'windows' && 'Windows' \|\| '???' }}	0s
ESLint	0s
Reindeer	0s
Clang Tidy	0s
Clippy	0s
Emscripten	2m 15s
Documentation	36s
Minimal versions	27s
Rust beta	1m 0s
Clang (no exceptions)	37s
Rust stable	1m 11s
Clang	1m 22s
C++14 on macOS	1m 14s
Cargo on Windows (msvc)	2m 7s
C++14 on Linux	1m 16s
Rust nightly	1m 13s
Rust 1.82.0	57s
C++17 on Linux	1m 13s
C++20 on macOS	1m 26s
Cargo on macOS	1m 19s
C++17 on macOS	53s
Pedantic	1m 8s
C++14 on Windows	2m 10s
C++20 on Windows	2m 48s
C++17 on Windows	1m 58s
C++20 on Linux	1m 9s
	28m 51s

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