add checkout step

* add VERSION_PREFIX argument

* add fmt example

* add VERSION_PREFIX note to readme

* rollback, add info about determining version from git tag

* rollback version

.github/workflows/publish.yaml

@@ -0,0 +1,21 @@
+name: Publish
+
+on:
+  push:
+    tags:
+      - '*'
+
+jobs:
+  build:
+    name: Publish CPM.cmake
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Upload CPM.cmake to release
+        uses: svenstaro/upload-release-action@v1-release
+        with:
+          repo_token: ${{ secrets.GITHUB_TOKEN }}
+          file: cmake/CPM.cmake
+          asset_name: CPM.cmake
+          tag: ${{ github.ref }}
+          overwrite: true

README.md

@@ -36,6 +36,7 @@ CPMAddPackage(
 
 The origin may be specified by a `GIT_REPOSITORY`, but other sources, such as direct URLs, are [also supported](https://cmake.org/cmake/help/v3.11/module/ExternalProject.html#external-project-definition).
 If `GIT_TAG` hasn't been explicitly specified it defaults to `v(VERSION)`, a common convention for git projects.
+On the other hand, if `VERSION` hasn't been explicitly specified, CPM can automatically identify the version from the git tag in some common cases. 
 `GIT_TAG` can also be set to a specific commit or a branch name such as `master` to always download the most recent version.
 The optional argument `FIND_PACKAGE_ARGUMENTS` can be specified to a string of parameters that will be passed to `find_package` if enabled (see below).
 

cmake/CPM.cmake

@@ -28,7 +28,7 @@
 
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
-set(CURRENT_CPM_VERSION 0.15.1)
+set(CURRENT_CPM_VERSION 0.17)
 
 if(CPM_DIRECTORY)
   if(NOT ${CPM_DIRECTORY} MATCHES ${CMAKE_CURRENT_LIST_DIR})
@@ -124,7 +124,7 @@ function(CPMAddPackage)
     OPTIONS
   )
 
-  cmake_parse_arguments(CPM_ARGS "" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+  cmake_parse_arguments(CPM_ARGS "" "${oneValueArgs}" "${multiValueArgs}" "${ARGN}")
 
   if(CPM_USE_LOCAL_PACKAGES OR CPM_LOCAL_PACKAGES_ONLY)
     cpm_find_package(${CPM_ARGS_NAME} "${CPM_ARGS_VERSION}" ${CPM_ARGS_FIND_PACKAGE_ARGUMENTS})
@@ -208,8 +208,9 @@ function(CPMAddPackage)
 
   if (DEFINED CPM_ARGS_DOWNLOAD_COMMAND)
     set(FETCH_CONTENT_DECLARE_EXTRA_OPTS DOWNLOAD_COMMAND ${CPM_ARGS_DOWNLOAD_COMMAND})
-  else()
-    if (CPM_SOURCE_CACHE AND NOT DEFINED CPM_ARGS_SOURCE_DIR)
+  elseif(DEFINED CPM_ARGS_SOURCE_DIR)
+    set(FETCH_CONTENT_DECLARE_EXTRA_OPTS SOURCE_DIR ${CPM_ARGS_SOURCE_DIR})
+  elseif (CPM_SOURCE_CACHE)
     string(TOLOWER ${CPM_ARGS_NAME} lower_case_name)
     set(origin_parameters ${CPM_ARGS_UNPARSED_ARGUMENTS})
     list(SORT origin_parameters)
@@ -225,7 +226,6 @@ function(CPMAddPackage)
       set(PACKAGE_INFO "${PACKAGE_INFO} -> ${download_directory}")
     endif()
   endif()
-  endif()
 
   cpm_declare_fetch(${CPM_ARGS_NAME} ${CPM_ARGS_VERSION} ${PACKAGE_INFO} "${CPM_ARGS_UNPARSED_ARGUMENTS}" ${FETCH_CONTENT_DECLARE_EXTRA_OPTS})
   cpm_fetch_package(${CPM_ARGS_NAME} ${DOWNLOAD_ONLY})
@@ -303,9 +303,15 @@ endfunction()
 # splits a package option
 function(cpm_parse_option OPTION)
   string(REGEX MATCH "^[^ ]+" OPTION_KEY ${OPTION})
+  string(LENGTH ${OPTION} OPTION_LENGTH)
   string(LENGTH ${OPTION_KEY} OPTION_KEY_LENGTH)
+  if (OPTION_KEY_LENGTH STREQUAL OPTION_LENGTH)
+    # no value for key provided, assume user wants to set option to "ON"
+    set(OPTION_VALUE "ON")
+  else()
     math(EXPR OPTION_KEY_LENGTH "${OPTION_KEY_LENGTH}+1")
     string(SUBSTRING ${OPTION} "${OPTION_KEY_LENGTH}" "-1" OPTION_VALUE)
+  endif()
   set(OPTION_KEY "${OPTION_KEY}" PARENT_SCOPE)
   set(OPTION_VALUE "${OPTION_VALUE}" PARENT_SCOPE)
 endfunction()

examples/fmt/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+project(CPMJSONExample)
+
+# ---- Dependencies ----
+
+include(../../cmake/CPM.cmake)
+
+CPMAddPackage(
+  NAME fmt
+  GIT_TAG 6.1.2
+  GITHUB_REPOSITORY fmtlib/fmt
+)
+
+# ---- Executable ----
+
+add_executable(CPMFmtExample "main.cpp")
+set_target_properties(CPMFmtExample PROPERTIES CXX_STANDARD 17)        
+target_link_libraries(CPMFmtExample fmt)

examples/fmt/main.cpp

@@ -0,0 +1,6 @@
+#include <fmt/format.h>
+
+int main(){
+  fmt::print("Hello, {}!\n", "world");
+  return 0;
+}

examples/gtest/CMakeLists.txt

@@ -23,7 +23,7 @@ CPMAddPackage(
   VERSION 1.8.1
   OPTIONS
       "INSTALL_GTEST OFF"
-      "gtest_force_shared_crt ON"
+      "gtest_force_shared_crt"
 )
 
 # ---- Create binary ----

test/unit/source_dir.cmake

@@ -0,0 +1,19 @@
+
+include(CMakePackageConfigHelpers)
+include(${CPM_PATH}/testing.cmake)
+
+set(TEST_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR}/source_dir)
+
+configure_package_config_file(
+  "${CMAKE_CURRENT_LIST_DIR}/source_dir/CMakeLists.txt.in"
+  "${CMAKE_CURRENT_LIST_DIR}/source_dir/CMakeLists.txt"
+  INSTALL_DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/junk
+)
+
+execute_process(
+  COMMAND 
+  ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/source_dir" "-B${TEST_BUILD_DIR}"
+  RESULT_VARIABLE ret
+)
+
+ASSERT_EQUAL(${ret} "0")

test/unit/source_dir/.gitignore

@@ -0,0 +1 @@
+/CMakeLists.txt

test/unit/source_dir/CMakeLists.txt.in

@@ -0,0 +1,20 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+project(CPMExampleCatch2)
+
+# ---- Options ----
+
+option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)
+
+# ---- Dependencies ----
+
+include(@CPM_PATH@/CPM.cmake)
+
+CPMAddPackage(
+  NAME Dependency
+  SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/dependency
+)
+
+# ---- Call dependency method to validate correct addition of directory ----
+
+dependency_function()

test/unit/source_dir/dependency/CMakeLists.txt

@@ -0,0 +1,4 @@
+
+function(dependency_function)
+  message("called external method")
+endfunction()