[PATCH] PR libstdc++/85749 constrain seed sequences for random number engines

[Jonathan Wakely]

Constrain constructors and member functions of random number engines so
that functions taking seed sequences can only be called with types that
meet the seed sequence requirements.

	PR libstdc++/85749
	* include/bits/random.h (__detail::__is_seed_seq): New SFINAE helper.
	(linear_congruential_engine, mersenne_twister_engine)
	(subtract_with_carry_engine, discard_block_engine)
	(independent_bits_engine, shuffle_order_engine): Use __is_seed_seq to
	constrain function templates taking seed sequences.
	* include/bits/random.tcc (linear_congruential_engine::seed(_Sseq&))
	(mersenne_twister_engine::seed(_Sseq&))
	(subtract_with_carry_engine::seed(_Sseq&)): Change return types to
	match declarations.
	* include/ext/random (simd_fast_mersenne_twister_engine): Use
	__is_seed_seq to constrain function templates taking seed sequences.
	* include/ext/random.tcc (simd_fast_mersenne_twister_engine::seed):
	Change return type to match declaration.
	* testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc:
	New.
	* testsuite/26_numerics/random/independent_bits_engine/cons/
	seed_seq2.cc: New.
	* testsuite/26_numerics/random/linear_congruential_engine/cons/
	seed_seq2.cc: New.
	* testsuite/26_numerics/random/mersenne_twister_engine/cons/
	seed_seq2.cc: New.
	* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error lineno.
	* testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc:
	New.
	* testsuite/26_numerics/random/subtract_with_carry_engine/cons/
	seed_seq2.cc: New.
	* testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/
	seed_seq2.cc: New.

Tested powerpc64le-linux, committed to trunk.


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