CDRIVER-4743 Define BSON_STATIC for bson_static build (#1453)

* remove `bson_obj`

Separate sources built by `bson_shared` and `bson_static`. This is intended to build `bson_static` sources with no `dllexport` and `bson_shared` with `dllexport`.

* define `BSON_STATIC` when building

To suppress `dllexport`. When `dllexport` is defined, it appears to export the symbols in a consumer.

* revise comments

BSON_STATIC and MONGOC_STATIC are defined for static builds.
Exporting functions in static build has an effect.

Author: kevinAlbs

src/libbson/CMakeLists.txt

@@ -171,84 +171,64 @@ file(GLOB_RECURSE all_sources CONFIGURE_DEPENDS
    "${mongo-c-driver_SOURCE_DIR}/src/common/*.c"
    )
 
-# The default object library for all libbson translation units:
-add_library(bson_obj OBJECT EXCLUDE_FROM_ALL ${all_sources})
-
-# The libbson object libraries that we will build
-set(bson_obj_libs bson_obj)
-
-if(ENABLE_PIC OR WIN32)
-   # User wants (or platform requires) static libs to use PIC code. Since we
-   # already need PIC for the dynamic library, we can consolidate things and
-   # use a single object library for both the static and the shared library.
-   # No duplicate compilations necessary!
-   set_property(TARGET bson_obj PROPERTY POSITION_INDEPENDENT_CODE TRUE)
-   # The bson_obj_pic is just an alias of the base library:
-   add_library(bson_obj_pic ALIAS bson_obj)
-else()
-   # User does not want PIC in the static library. In that case, we just need a second object
-   # library that has PIC enabled so it can be used in creating the dynamic library.
-   add_library(bson_obj_pic OBJECT EXCLUDE_FROM_ALL ${all_sources})
-   set_property(TARGET bson_obj_pic PROPERTY POSITION_INDEPENDENT_CODE TRUE)
-   list(APPEND bson_obj_libs bson_obj_pic)
-endif()
-
-# Set target properties for the object libraries.
-mongo_target_requirements(
-   ${bson_obj_libs}
-   LINK_LIBRARIES
-      PUBLIC
-         _libbson_build_interface
-   COMPILE_DEFINITIONS
-      PRIVATE
-         # Tell headers that they are part of compilation:
-         BSON_COMPILATION
-         # Enable NaN parsing in jsonsl
-         JSONSL_PARSE_NAN
-         # Set the name mangling scheme for the common libraries
-         MCOMMON_NAME_PREFIX=_bson_mcommon
-   COMPILE_OPTIONS
-      PRIVATE
-         # Macro constant INFINITY triggers constant arithmetic overflow warnings in
-         # VS 2013, but VS 2013 doesn't support inline warning suppression.
-         # Remove once support for VS 2013 is dropped.
-         $<$<AND:$<C_COMPILER_ID:MSVC>,$<VERSION_LESS:${MSVC_VERSION},1900>>:/wd4756>
-)
-
 # List of the primary BSON library targets that we are building
 set(bson_libs)
 
 if(ENABLE_STATIC)
-   add_library(bson_static STATIC)
-   target_link_libraries(bson_static PRIVATE $<BUILD_INTERFACE:bson_obj>)
+   add_library(bson_static STATIC ${all_sources})
    list(APPEND bson_libs bson_static)
+   # Define `BSON_STATIC` when building to suppress the annotation __declspec(dllexport).
+   # This prevents consumers of bson_static from exporting the symbols.
+   target_compile_definitions(bson_static PRIVATE BSON_STATIC)
    # When consumers link against bson_static, suppress the annotation __declspec(dllimport),
    # since those symbols will be available immediately at the link step:
    target_compile_definitions(bson_static INTERFACE BSON_STATIC)
+
+   if(ENABLE_PIC)
+      # User wants static libs to use PIC code.
+      set_property(TARGET bson_static PROPERTY POSITION_INDEPENDENT_CODE TRUE)
+   endif()
 endif()
 
 if(ENABLE_SHARED)
-   add_library(bson_shared SHARED)
+   add_library(bson_shared SHARED  ${all_sources})
    if(WIN32)
       # Add resource-definition script for Windows shared library (.dll).
       configure_file(libbson.rc.in libbson.rc)
       target_sources(bson_shared PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/libbson.rc)
    endif()
-   target_link_libraries(bson_shared PRIVATE $<BUILD_INTERFACE:bson_obj_pic>)
    list(APPEND bson_libs bson_shared)
 endif()
 
 if(NOT bson_libs)
    message(FATAL_ERROR "Neither bson_shared nor bson_static is going to be built. Did you mean to enable at least one of them?")
 endif()
 
+# Set target properties for the libraries.
 mongo_target_requirements(
-   ${bson_libs} LINK_LIBRARIES PUBLIC
-   # Build-local requirements:
-   $<BUILD_INTERFACE:_libbson_build_interface>
-   # Include in the install interface explicitly:
-   mongo::detail::c_platform
+   ${bson_libs}
+   LINK_LIBRARIES
+      PUBLIC
+         # Build-local requirements:
+         $<BUILD_INTERFACE:_libbson_build_interface>
+         # Include in the install interface explicitly:
+         mongo::detail::c_platform
+   COMPILE_DEFINITIONS
+      PRIVATE
+         # Tell headers that they are part of compilation:
+         BSON_COMPILATION
+         # Enable NaN parsing in jsonsl
+         JSONSL_PARSE_NAN
+         # Set the name mangling scheme for the common libraries
+         MCOMMON_NAME_PREFIX=_bson_mcommon
+   COMPILE_OPTIONS
+      PRIVATE
+         # Macro constant INFINITY triggers constant arithmetic overflow warnings in
+         # VS 2013, but VS 2013 doesn't support inline warning suppression.
+         # Remove once support for VS 2013 is dropped.
+         $<$<AND:$<C_COMPILER_ID:MSVC>,$<VERSION_LESS:${MSVC_VERSION},1900>>:/wd4756>
 )
+
 set_target_properties(${bson_libs} PROPERTIES
    VERSION "0.0.0"
    SOVERSION "0"

src/libbson/src/bson/bson-macros.h

@@ -66,11 +66,10 @@
 
 
 /* Decorate public functions:
- * - if BSON_STATIC, we're compiling a program that uses libbson as a static
- *   library, don't decorate functions
- * - else if BSON_COMPILATION, we're compiling a static or shared libbson, mark
- *   public functions for export from the shared lib (which has no effect on
- *   the static lib)
+ * - if BSON_STATIC, we're compiling a static libbson or a program
+ *   that uses libbson as a static library. Don't decorate functions.
+ * - else if BSON_COMPILATION, we're compiling a shared libbson, mark
+ *   public functions for export from the shared lib
  * - else, we're compiling a program that uses libbson as a shared library,
  *   mark public functions as DLL imports for Microsoft Visual C
  */

src/libmongoc/src/mongoc/mongoc-macros.h

@@ -20,11 +20,10 @@
 #define MONGOC_MACROS_H
 
 /* Decorate public functions:
- * - if MONGOC_STATIC, we're compiling a program that uses libmongoc as
- *   a static library, don't decorate functions
- * - else if MONGOC_COMPILATION, we're compiling a static or shared libmongoc,
- *   mark public functions for export from the shared lib (which has no effect
- *   on the static lib)
+ * - if MONGOC_STATIC, we're compiling a static libmongoc or a program
+ *   that uses libmongoc as a static library. Don't decorate functions
+ * - else if MONGOC_COMPILATION, we're compiling a shared libmongoc,
+ *   mark public functions for export from the shared lib.
  * - else, we're compiling a program that uses libmongoc as a shared library,
  *   mark public functions as DLL imports for Microsoft Visual C.
  */