(#9044) grpc: fix cross-build + provide all CMake executable imported…

… targets + add shared option + modernize

* modernize

* provide all CMake executables targets

* fix cross-build & patch in build() instead of source()

* fix test package

link of targets was broken. It was working only due to global injection of many stuff through conan_basic_setup()

* simplify test package

* add shared option

* do not test shared if cross-building

this a limitation of current conan model. Could be enabled again with CMakeToolchain + VirtualBuildEnv.

* fix cross-build to iOS

* handle codegen option in package_info()

* secure option doesn't affect package_id

this option doesn't exist upstream. It's a hack to hide unsecure components in global target generated by conan.

* drop shared with libstdc++/libstdc++11 for the moment

* test package: help gprc_cpp_plugin to find grpc_plugin_support if shared at build time

* handle cross-build in test package

* typo

* gRPC shared buils fine with clang on Linux

* fix install of plugins if cross-building

this bug exists in all versions of the range [1.39.0;1.42.0[

* with gcc allow grpc shared if abseil shared

it allows folks to create grpc shared, but we should find a way to compile with gcc grpc shared against abseil static

* really use @relative_path@

recipes/grpc/all/CMakeLists.txt

@@ -2,6 +2,6 @@ cmake_minimum_required(VERSION 2.8.12)
 project(cmake_wrapper)
 
 include(conanbuildinfo.cmake)
-conan_basic_setup()
+conan_basic_setup(KEEP_RPATHS)
 
 add_subdirectory("source_subfolder")

recipes/grpc/all/cmake/grpc_plugin_template.cmake.in

@@ -0,0 +1,31 @@
+if(NOT TARGET @target_name@)
+    if(CMAKE_CROSSCOMPILING)
+        find_program(@find_program_variable@
+            NAMES @executable_name@
+            PATHS ENV PATH
+            NO_DEFAULT_PATH
+        )
+    else()
+        find_program(@find_program_variable@
+            NAMES @executable_name@
+            PATHS "${CMAKE_CURRENT_LIST_DIR}/@relative_path@bin/"
+            NO_DEFAULT_PATH
+        )
+    endif()
+    # TODO: In conan v2 with CMakeToolchain, can be replaced by:
+    # find_program(@find_program_variable@ NAMES @executable_name@))
+    # # Nice enough to handle grpc not in build_requires for native build
+    # if(NOT @find_program_variable@ AND NOT CMAKE_CROSSCOMPILING)
+    #     find_program(@find_program_variable@
+    #         NAMES @executable_name@
+    #         PATHS "${CMAKE_CURRENT_LIST_DIR}/@relative_path@bin/"
+    #         NO_DEFAULT_PATH
+    #     )
+    # endif()
+
+    if(@find_program_variable@)
+        get_filename_component(@find_program_variable@ "${@find_program_variable@}" ABSOLUTE)
+        add_executable(@target_name@ IMPORTED)
+        set_property(TARGET @target_name@ PROPERTY IMPORTED_LOCATION ${@find_program_variable@})
+    endif()
+endif()