[google-cloud-cpp] Fix libcurl linkage (#5968)

* [google-cloud-cpp] Fix libcurl linkage

* [curl] Fix libcurl exported CMake target config (Windows)

1 files changed, 142 insertions, 0 deletions

diff --git a/ports/google-cloud-cpp/cmake-libcurl-find-config.patch b/ports/google-cloud-cpp/cmake-libcurl-find-config.patch
new file mode 100644
index 000000000..0c1d6dd6f
--- /dev/null
+++ b/ports/google-cloud-cpp/cmake-libcurl-find-config.patch
@@ -0,0 +1,142 @@
+diff --git a/cmake/IncludeCurl.cmake b/cmake/IncludeCurl.cmake
+index 6ea7ca3e6..3c2db6b28 100644
+--- a/cmake/IncludeCurl.cmake
++++ b/cmake/IncludeCurl.cmake
+@@ -34,49 +34,57 @@ set_property(CACHE GOOGLE_CLOUD_CPP_CURL_PROVIDER
+ if ("${GOOGLE_CLOUD_CPP_CURL_PROVIDER}" STREQUAL "external")
+     include(external/curl)
+ elseif("${GOOGLE_CLOUD_CPP_CURL_PROVIDER}" STREQUAL "package")
+-    # Search for libcurl, in CMake 3.5 this does not define a target, but it
+-    # will in 3.12 (see https://cmake.org/cmake/help/git-
+-    # stage/module/FindCURL.html for details).  Until then, define the target
+-    # ourselves if it is missing.
+-    find_package(CURL REQUIRED)
+-    if (NOT TARGET CURL::libcurl)
+-        add_library(CURL::libcurl UNKNOWN IMPORTED)
+-        set_property(TARGET CURL::libcurl
+-                     APPEND
+-                     PROPERTY INTERFACE_INCLUDE_DIRECTORIES
+-                              "${CURL_INCLUDE_DIR}")
+-        set_property(TARGET CURL::libcurl
+-                     APPEND
+-                     PROPERTY IMPORTED_LOCATION "${CURL_LIBRARY}")
+-    endif ()
+-    # If the library is static, we need to explicitly link its dependencies.
+-    # However, we should not do so for shared libraries, because the version of
+-    # OpenSSL (for example) found by find_package() may be newer than the
+-    # version linked against libcurl.
+-    if ("${CURL_LIBRARY}" MATCHES "${CMAKE_STATIC_LIBRARY_SUFFIX}$")
+-        find_package(OpenSSL REQUIRED)
+-        find_package(ZLIB REQUIRED)
+-        set_property(TARGET CURL::libcurl
+-                     APPEND
+-                     PROPERTY INTERFACE_LINK_LIBRARIES
+-                              OpenSSL::SSL
+-                              OpenSSL::Crypto
+-                              ZLIB::ZLIB)
+-        message(STATUS "CURL linkage will be static")
+-        if (WIN32)
++    # Search for libcurl, first using CONFIG mode, and retrying
++    # using MODULE mode if that fails
++    find_package(CURL CONFIG QUIET) # Deliberately quiet, so we can handle the result
++    if(CURL_FOUND)
++        message(STATUS "CURL library found via CONFIG mode")
++    else()
++        # CONFIG mode failed - fallback to MODULE mode
++        # In CMake 3.5 this does not define a target, but it
++        # will in 3.12 (see https://cmake.org/cmake/help/git-
++        # stage/module/FindCURL.html for details).  Until then, define the target
++        # ourselves if it is missing.
++        find_package(CURL MODULE REQUIRED) # Use REQUIRED the second time to fail out
++        if (NOT TARGET CURL::libcurl)
++            add_library(CURL::libcurl UNKNOWN IMPORTED)
+             set_property(TARGET CURL::libcurl
+                          APPEND
+-                         PROPERTY INTERFACE_LINK_LIBRARIES
+-                                  crypt32
+-                                  wsock32
+-                                  ws2_32)
++                         PROPERTY INTERFACE_INCLUDE_DIRECTORIES
++                                  "${CURL_INCLUDE_DIR}")
++            set_property(TARGET CURL::libcurl
++                         APPEND
++                         PROPERTY IMPORTED_LOCATION "${CURL_LIBRARY}")
+         endif ()
+-        if (APPLE)
++        # If the library is static, we need to explicitly link its dependencies.
++        # However, we should not do so for shared libraries, because the version of
++        # OpenSSL (for example) found by find_package() may be newer than the
++        # version linked against libcurl.
++        if ("${CURL_LIBRARY}" MATCHES "${CMAKE_STATIC_LIBRARY_SUFFIX}$")
++            find_package(OpenSSL REQUIRED)
++            find_package(ZLIB REQUIRED)
+             set_property(TARGET CURL::libcurl
+                          APPEND
+-                         PROPERTY INTERFACE_LINK_LIBRARIES ldap)
++                         PROPERTY INTERFACE_LINK_LIBRARIES
++                                  OpenSSL::SSL
++                                  OpenSSL::Crypto
++                                  ZLIB::ZLIB)
++            message(STATUS "CURL linkage will be static")
++            if (WIN32)
++                set_property(TARGET CURL::libcurl
++                             APPEND
++                             PROPERTY INTERFACE_LINK_LIBRARIES
++                                      crypt32
++                                      wsock32
++                                      ws2_32)
++            endif ()
++            if (APPLE)
++                set_property(TARGET CURL::libcurl
++                             APPEND
++                             PROPERTY INTERFACE_LINK_LIBRARIES ldap)
++            endif ()
++        else()
++            message(STATUS "CURL linkage will be non-static")
+         endif ()
+-    else()
+-        message(STATUS "CURL linkage will be non-static")
+     endif ()
+ endif ()
+diff --git a/google/cloud/storage/config.cmake.in b/google/cloud/storage/config.cmake.in
+index a4d261815..640089e09 100644
+--- a/google/cloud/storage/config.cmake.in
++++ b/google/cloud/storage/config.cmake.in
+@@ -13,21 +13,25 @@
+ # limitations under the License.
+ 
+ include(CMakeFindDependencyMacro)
+-find_dependency(CURL)
++# Search for libcurl, first using CONFIG mode, and retrying
++# using MODULE mode if that fails
++find_package(CURL CONFIG QUIET) # find_package so we can explicitly specify QUIET
++if(NOT CURL_FOUND)
++    find_dependency(CURL MODULE)
++    # Some versions of FindCURL do not define CURL::libcurl, so we define it ourselves.
++    if (NOT TARGET CURL::libcurl)
++        add_library(CURL::libcurl UNKNOWN IMPORTED)
++        set_property(TARGET CURL::libcurl
++                     APPEND
++                     PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${CURL_INCLUDE_DIR}")
++        set_property(TARGET CURL::libcurl
++                     APPEND
++                     PROPERTY IMPORTED_LOCATION "${CURL_LIBRARY}")
++    endif ()
++endif()
+ find_dependency(Crc32c)
+ find_dependency(google_cloud_cpp_common)
+ find_dependency(OpenSSL)
+ find_dependency(ZLIB)
+ 
+-# Some versions of FindCURL do not define CURL::libcurl, so we define it ourselves.
+-if (NOT TARGET CURL::libcurl)
+-    add_library(CURL::libcurl UNKNOWN IMPORTED)
+-    set_property(TARGET CURL::libcurl
+-                 APPEND
+-                 PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${CURL_INCLUDE_DIR}")
+-    set_property(TARGET CURL::libcurl
+-                 APPEND
+-                 PROPERTY IMPORTED_LOCATION "${CURL_LIBRARY}")
+-endif ()
+-
+ include("${CMAKE_CURRENT_LIST_DIR}/storage-targets.cmake")