d: Fix internal compiler error: in layout_aggregate_type, at d/types.cc:574

d: Fix internal compiler error: in layout_aggregate_type, at d/types.cc:574

This ICE is specific to the D front-end language version in GDC 12.

	PR d/110959

gcc/d/ChangeLog:

	* dmd/canthrow.d (Dsymbol_canThrow): Use foreachVar.
	* dmd/declaration.d (TupleDeclaration::needThis): Likewise.
	(TupleDeclaration::foreachVar): New function.
	(VarDeclaration::setFieldOffset): Use foreachVar.
	* dmd/dinterpret.d (Interpreter::visit (DeclarationExp)): Likewise.
	* dmd/dsymbolsem.d (DsymbolSemanticVisitor::visit (VarDeclaration)):
	Don't push tuple field members to the scope symbol table.
	(determineFields): Handle pushing tuple field members here instead.
	* dmd/dtoh.d (ToCppBuffer::visit (VarDeclaration)): Visit all tuple
	fields.
	(ToCppBuffer::visit (TupleDeclaration)): New function.
	* dmd/expression.d (expandAliasThisTuples): Use foreachVar.
	* dmd/foreachvar.d (VarWalker::visit (DeclarationExp)): Likewise.
	* dmd/ob.d (genKill): Likewise.
	(checkObErrors): Likewise.
	* dmd/semantic2.d (Semantic2Visitor::visit (TupleDeclaration)): Visit
	all tuple fields.

gcc/testsuite/ChangeLog:

	* gdc.dg/pr110959.d: New test.
	* gdc.test/runnable/test23010.d: New test.