if version=latest, use the last tagged version in repository

cmake/CPM.cmake

@@ -178,6 +178,26 @@ if(NOT CPM_DONT_CREATE_PACKAGE_LOCK)
   )
 endif()
 
+# look for string in TAG like "latest" or "master"
+function(cpm_fetch_git_tag_from_version_description URI RESULT)
+    find_package(Git REQUIRED)
+    if(NOT GIT_EXECUTABLE)
+        return()
+    endif()
+
+    # TODO: if not tag exists in rep, revert to last checkin
+    # TODO: make it work for case of multuple URI
+    # TODO: replace tail and sed with string functions so we don't have to call bash
+    set(CMD "${GIT_EXECUTABLE} ls-remote --refs --heads --tags --sort=v:refname ${URI} | tail -1 | sed 's:.*refs/tags/::' " )
+    execute_process(
+        COMMAND bash "-c" ${CMD}
+        OUTPUT_VARIABLE OUT
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
+    message("found latest tag: ${OUT} from ${URI}")
+    set(${RESULT} ${OUT} PARENT_SCOPE)
+endfunction()
+
 include(FetchContent)
 
 # Try to infer package name from git repository uri (path or url)
@@ -543,11 +563,6 @@ function(CPMAddPackage)
 
   # Set default values for arguments
 
-  if(NOT DEFINED CPM_ARGS_VERSION)
-    if(DEFINED CPM_ARGS_GIT_TAG)
-      cpm_get_version_from_git_tag("${CPM_ARGS_GIT_TAG}" CPM_ARGS_VERSION)
-    endif()
-  endif()
 
   if(CPM_ARGS_DOWNLOAD_ONLY)
     set(DOWNLOAD_ONLY ${CPM_ARGS_DOWNLOAD_ONLY})
@@ -577,6 +592,19 @@ function(CPMAddPackage)
 
   set(CPM_SKIP_FETCH FALSE)
 
+  # if "latest" version is specified, look at repository for last tagged version
+  if(DEFINED CPM_ARGS_GIT_REPOSITORY AND DEFINED CPM_ARGS_VERSION)
+    if(${CPM_ARGS_VERSION} MATCHES "^latest$")
+        cpm_fetch_git_tag_from_version_description(${CPM_ARGS_GIT_REPOSITORY} CPM_ARGS_GIT_TAG)
+    endif()
+  endif()
+
+  if(NOT DEFINED CPM_ARGS_VERSION)
+    if(DEFINED CPM_ARGS_GIT_TAG)
+      cpm_get_version_from_git_tag("${CPM_ARGS_GIT_TAG}" CPM_ARGS_VERSION)
+    endif()
+  endif()
+
   if(DEFINED CPM_ARGS_GIT_TAG)
     list(APPEND CPM_ARGS_UNPARSED_ARGUMENTS GIT_TAG ${CPM_ARGS_GIT_TAG})
     # If GIT_SHALLOW is explicitly specified, honor the value.

test/unit/tag_when_version_is_latest.cmake

@@ -0,0 +1,38 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+include(${CPM_PATH}/testing.cmake)
+include(CMakePackageConfigHelpers)
+
+set(CPM_SOURCE_CACHE_DIR "${CMAKE_CURRENT_BINARY_DIR}/CPM")
+set(TEST_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR}/version_latest)
+
+function(clear_cache)
+  message(STATUS "clearing CPM cache")
+  file(REMOVE_RECURSE ${CPM_SOURCE_CACHE_DIR})
+  assert_not_exists("${CPM_SOURCE_CACHE_DIR}")
+endfunction()
+
+function(update_cmake_lists)
+  configure_package_config_file(
+    "${CMAKE_CURRENT_LIST_DIR}/version_latest/CMakeLists.txt.in"
+    "${CMAKE_CURRENT_LIST_DIR}/version_latest/CMakeLists.txt"
+    INSTALL_DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/junk
+  )
+endfunction()
+
+function(reset_test)
+  clear_cache()
+  file(REMOVE_RECURSE ${TEST_BUILD_DIR})
+  update_cmake_lists()
+endfunction()
+
+# Read CPM_SOURCE_CACHE from arguments
+
+reset_test()
+
+execute_process(
+  COMMAND ${CMAKE_COMMAND} "-S${CMAKE_CURRENT_LIST_DIR}/version_latest"
+          "-B${TEST_BUILD_DIR}" "-DCPM_SOURCE_CACHE=${CPM_SOURCE_CACHE_DIR}" RESULT_VARIABLE ret
+)
+
+assert_equal(${ret} "0")

test/unit/version_latest/.gitignore

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

test/unit/version_latest/CMakeLists.txt.in

@@ -0,0 +1,33 @@
+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 fibonacci
+  GIT_REPOSITORY https://github.com/cpm-cmake/testpack-fibonacci.git
+  VERSION latest
+)
+
+
+# ---- Create binary ----
+
+add_executable(CPMExampleCatch2 main.cpp)
+target_link_libraries(CPMExampleCatch2 fibonacci)
+set_target_properties(CPMExampleCatch2 PROPERTIES CXX_STANDARD 17 COMPILE_FLAGS "-Wall -pedantic -Wextra -Werror")
+
+# ---- Check parameters ----
+
+include(@CPM_PATH@/testing.cmake)
+
+ASSERT_TRUTHY(fibonacci_ADDED)
+ASSERT_DEFINED(fibonacci_SOURCE_DIR)
+ASSERT_DEFINED(fibonacci_BINARY_DIR)
+ASSERT_EQUAL("${CPM_LAST_PACKAGE_NAME}" "fibonacci")

test/unit/version_latest/main.cpp

@@ -0,0 +1,10 @@
+#define CATCH_CONFIG_MAIN
+
+#include <fibonacci.h>
+
+#include <iostream>
+
+int main() {
+  std::cout << "fib(10) = " << fastFibonacci(10) << std::endl;
+  return 0;
+}