Add parameter to corrosion_import_crate to return list of added targe…

…ts (#312)

* Allow retrieving list of imported crates
* Write about retrieving imported crates list in docs

(cherry picked from commit 44749a9)

README.md

@@ -196,6 +196,8 @@ corrosion_import_crate(MANIFEST_PATH <path/to/cargo.toml>
         [NO_LINKER_OVERRIDE]
         # Specify  cargo build profile (e.g. release or a custom profile)
         [PROFILE <cargo-profile>]
+        # Retrieve the list of imported crates in the current scope
+        [IMPORTED_CRATES <variable-name>]
         # Build only the specified crate types (Ignored with CMake < 3.19)
         [CRATE_TYPES <crate_type1> ... <crate_typeN>]
         # Only import the specified crates from a workspace

cmake/Corrosion.cmake

@@ -1070,7 +1070,7 @@ endfunction()
 
 function(corrosion_import_crate)
     set(OPTIONS ALL_FEATURES NO_DEFAULT_FEATURES NO_STD NO_LINKER_OVERRIDE)
-    set(ONE_VALUE_KEYWORDS MANIFEST_PATH PROFILE)
+    set(ONE_VALUE_KEYWORDS MANIFEST_PATH PROFILE IMPORTED_CRATES)
     set(MULTI_VALUE_KEYWORDS CRATE_TYPES CRATES FEATURES FLAGS)
     cmake_parse_arguments(COR "${OPTIONS}" "${ONE_VALUE_KEYWORDS}" "${MULTI_VALUE_KEYWORDS}" ${ARGN})
 
@@ -1154,6 +1154,10 @@ function(corrosion_import_crate)
             PROFILE
                 "${COR_PROFILE}"
         )
+
+        if (DEFINED COR_IMPORTED_CRATES)
+            set(${COR_IMPORTED_CRATES} ${imported_crates} PARENT_SCOPE)
+        endif()
     endif()
 endfunction(corrosion_import_crate)
 

cmake/CorrosionGenerator.cmake

@@ -217,6 +217,8 @@ function(_generator_add_cargo_targets no_linker_override)
         message(DEBUG "Corrosion created the following CMake targets: ${created_targets}")
     endif()
 
+    set(imported_crates ${created_targets} PARENT_SCOPE)
+
     foreach(target_name ${created_targets})
         foreach(output_var RUNTIME_OUTPUT_DIRECTORY ARCHIVE_OUTPUT_DIRECTORY LIBRARY_OUTPUT_DIRECTORY PDB_OUTPUT_DIRECTORY)
             get_target_property(output_dir ${target_name} "${output_var}")