Allow building Catch2 as dynamic library

Also have a check that warns users if they try to combined dynamic
library with hidden visibility, which we do not support.

Closes #2397
Closes #2398

Author: horenmar

src/CMakeLists.txt

@@ -285,9 +285,7 @@ set(REPORTER_SOURCES
 )
 set(REPORTER_FILES ${REPORTER_HEADERS} ${REPORTER_SOURCES})
 
-# Fixme: STATIC because for dynamic, we would need to handle visibility
-# and I don't want to do the annotations right now
-add_library(Catch2 STATIC
+add_library(Catch2
   ${REPORTER_FILES}
   ${INTERNAL_FILES}
   ${BENCHMARK_HEADERS}
@@ -340,7 +338,7 @@ target_include_directories(Catch2
 )
 
 
-add_library(Catch2WithMain STATIC
+add_library(Catch2WithMain
     ${SOURCES_DIR}/internal/catch_main.cpp
 )
 add_build_reproducibility_settings(Catch2WithMain)
@@ -431,3 +429,20 @@ endif()
 
 list(APPEND CATCH_WARNING_TARGETS Catch2 Catch2WithMain)
 set(CATCH_WARNING_TARGETS ${CATCH_WARNING_TARGETS} PARENT_SCOPE)
+
+
+# We still do not support building dynamic library with hidden visibility
+# so we want to check & warn users if they do this. However, we won't abort
+# the configuration step so that we don't have to also provide an override.
+if (BUILD_SHARED_LIBS)
+    get_target_property(_VisPreset Catch2 CXX_VISIBILITY_PRESET)
+    get_target_property(_ExportAll Catch2 WINDOWS_EXPORT_ALL_SYMBOLS)
+    if (MSVC AND NOT _ExportAll
+        OR _VisPreset STREQUAL "hidden")
+
+        message(WARNING
+          "Catch2 does not support being built as a dynamic library with hidden"
+          " visibility. You have to ensure that visibility is handled yourself."
+        )
+    endif()
+endif()