PR c++/60228
* parser.c (cp_parser_omp_declare_reduction_exprs): If
processing_template_decl, wrap the combiner or initializer
into EXPR_STMT.
* decl.c (start_preparsed_function): Don't start a lambda scope
for DECL_OMP_DECLARE_REDUCTION_P functions.
(finish_function): Don't finish a lambda scope for
DECL_OMP_DECLARE_REDUCTION_P functions, nor cp_fold_function
them nor cp_genericize them.
* mangle.c (decl_mangling_context): Look through
DECL_OMP_DECLARE_REDUCTION_P functions.
* semantics.c (expand_or_defer_fn_1): For DECL_OMP_DECLARE_REDUCTION_P
functions, use tentative linkage, don't keep their bodies with
-fkeep-inline-functions and return false at the end.
* g++.dg/gomp/openmp-simd-2.C: Don't expect bodies for
DECL_OMP_DECLARE_REDUCTION_P functions.
* testsuite/libgomp.c++/udr-20.C: New test.
* testsuite/libgomp.c++/udr-21.C: New test.
From-SVN: r278831
