Not compiling with clang19

Summary:

Models do not compile with clang19. @SteveBronder or @WardBrian do you know what this means?

Description:

From https://www.stats.ox.ac.uk/pub/bdr/clang19/AovBay.log , which like rstanarm depends on rstan, StanHeaders, etc.

In file included from stanExports_onewaymodel.cc:5:
In file included from ./stanExports_onewaymodel.h:25:
In file included from /data/gannet/ripley/R/test-clang/StanHeaders/include/src/stan/model/model_header.hpp:11:
/data/gannet/ripley/R/test-clang/StanHeaders/include/src/stan/model/model_base_crtp.hpp:140:50: error: a template argument list is expected after a name prefixed by the template keyword [-Wmissing-template-arg-list-after-template-kw]
  140 |     return static_cast<const M*>(this)->template write_array(
      |                                                  ^
/data/gannet/ripley/R/test-clang/StanHeaders/include/src/stan/model/model_base_crtp.hpp:209:50: error: a template argument list is expected after a name prefixed by the template keyword [-Wmissing-template-arg-list-after-template-kw]
  209 |     return static_cast<const M*>(this)->template write_array(
      |                                                  ^

Reproducible Steps:

Try to compile a model with clang19

Current Output:

None

Expected Output:

A compiled stanmodel object

RStan Version:

2.31.x

R Version:

4.4.x

Operating System:

Linux

Reproduce the clang19 model compilation using the linked AovBay.log and inspect StanHeaders/include/src/stan/model/model_base_crtp.hpp at the reported write_array calls. Trace the includes from stanExports_onewaymodel.cc through stanExports_onewaymodel.h, then verify that an RStan 2.31.x model produces a compiled stanmodel object without the reported errors.