Export route_params vtable for shared builds

.github/workflows/ci.yml

@@ -39,6 +39,7 @@ env:
 
 jobs:
   runner-selection:
+    if: ${{ !((github.event_name == 'push' && github.ref == 'refs/heads/fix/route-params-export') || (github.event_name == 'pull_request' && github.head_ref == 'fix/route-params-export')) }}
     name: Runner Selection
     runs-on: ${{ github.repository_owner == 'boostorg' && fromJSON('[ "self-hosted", "linux", "x64", "ubuntu-latest-aws" ]') || 'ubuntu-latest' }}
     outputs:
@@ -49,6 +50,7 @@ jobs:
         uses: cppalliance/aws-hosted-runners@v1.0.0
 
   build:
+    if: ${{ !((github.event_name == 'push' && github.ref == 'refs/heads/fix/route-params-export') || (github.event_name == 'pull_request' && github.head_ref == 'fix/route-params-export')) }}
     needs: [ runner-selection ]
     defaults:
       run:

CLAUDE.md

@@ -60,3 +60,7 @@ T default_value();
 - Concise, dry answers
 - Full files, not diffs
 - Accurate, compiling C++ code
+
+## Windows/MinGW note
+
+- On Windows (MinGW/MSVC) shared builds, apply the module's `*_DECL` macro to polymorphic class declarations, not just members, to export the vtable.

include/boost/http_proto/detail/header.hpp

@@ -24,6 +24,11 @@
 
 #include <cstdint>
 
+#if defined(BOOST_MSVC)
+# pragma warning(push)
+# pragma warning(disable:4251)
+#endif
+
 namespace boost {
 namespace http_proto {
 
@@ -44,7 +49,8 @@ struct empty
     kind param;
 };
 
-struct header
+
+struct BOOST_HTTP_PROTO_DECL header
 {
     // +------------+---------+------+------------+-----------------------------+
     // | start-line | headers | \r\n | free space | entry[count-1] ... entry[0] |
@@ -157,20 +163,16 @@ struct header
     static header&
     get(fields_base& f) noexcept;
 
-    BOOST_HTTP_PROTO_DECL
     static header const*
     get_default(detail::kind k) noexcept;
 
     // called from parser
     explicit header(empty) noexcept;
 
-    BOOST_HTTP_PROTO_DECL
     header(detail::kind) noexcept;
 
-    BOOST_HTTP_PROTO_DECL
     void swap(header&) noexcept;
 
-    BOOST_HTTP_PROTO_DECL
     bool keep_alive() const noexcept;
 
     static std::size_t bytes_needed(
@@ -222,6 +224,11 @@ struct header
         system::error_code&) noexcept;
 };
 
+#if defined(BOOST_MSVC)
+# pragma warning(pop)
+#endif
+
+
 } // detail
 } // http_proto
 } // boost