build: gracefully handle error in git-version #19289

- only update git-version if both of these conditions are met:
    - `git` command succeeds
    - `versiondef_git.h` would change (SHA1-diff)
- else print a status/warning message

also move version generation out of Lua into cmake.

cmake/GenerateVersion.cmake

@@ -0,0 +1,47 @@
+# Handle generating version from Git.
+set(use_git_version 0)
+if(NVIM_VERSION_MEDIUM)
+  message(STATUS "USING NVIM_VERSION_MEDIUM: ${NVIM_VERSION_MEDIUM}")
+  return()
+endif()
+
+find_program(GIT_EXECUTABLE git)
+if(NOT GIT_EXECUTABLE)
+  message(AUTHOR_WARNING "Skipping version-string generation (cannot find git)")
+  return()
+endif()
+
+execute_process(
+  COMMAND git describe --first-parent --tags --always --dirty
+  OUTPUT_VARIABLE GIT_TAG
+  ERROR_VARIABLE ERR
+  RESULT_VARIABLE RES
+)
+
+if("${RES}" EQUAL 1)
+  if(EXISTS ${OUTPUT})
+    message(STATUS "Unable to extract version-string from git: keeping the last known version")
+  else()
+    # this will only be executed once since the file will get generated afterwards
+    message(AUTHOR_WARNING "Git tag extraction failed with: " "${ERR}")
+    file(WRITE "${OUTPUT}" "")
+  endif()
+  return()
+endif()
+
+string(STRIP "${GIT_TAG}" GIT_TAG)
+string(REGEX REPLACE "^v[0-9]+.[0-9]+.[0-9]+-" "" NVIM_VERSION_GIT "${GIT_TAG}")
+set(NVIM_VERSION_MEDIUM
+    "v${NVIM_VERSION_MAJOR}.${NVIM_VERSION_MINOR}.${NVIM_VERSION_PATCH}-dev-${NVIM_VERSION_GIT}"
+)
+set(NVIM_VERSION_STRING "#define NVIM_VERSION_MEDIUM \"${NVIM_VERSION_MEDIUM}\"\n")
+string(SHA1 CURRENT_VERSION_HASH "${NVIM_VERSION_STRING}")
+
+if(EXISTS ${OUTPUT})
+  file(SHA1 "${OUTPUT}" NVIM_VERSION_HASH)
+endif()
+
+if(NOT "${NVIM_VERSION_HASH}" STREQUAL "${CURRENT_VERSION_HASH}")
+  message(STATUS "Updating NVIM_VERSION_MEDIUM: ${NVIM_VERSION_MEDIUM}")
+  file(WRITE "${OUTPUT}" "${NVIM_VERSION_STRING}")
+endif()

scripts/update_version_stamp.lua

@@ -1,54 +0,0 @@
-#!/usr/bin/env lua
---
--- Script to update the Git version stamp during build.
--- This is called via the custom update_version_stamp target in
--- src/nvim/CMakeLists.txt.
---
--- arg[1]: file in which to update the version string
--- arg[2]: prefix to use always ("vX.Y.Z")
-
-local function die(msg)
-  io.stderr:write(string.format('%s: %s\n', arg[0], msg))
-  -- No error, fall back to using generated "-dev" version.
-  os.exit(0)
-end
-
-local function iswin()
-  return package.config:sub(1,1) == '\\'
-end
-
-if #arg ~= 2 then
-  die(string.format("Expected two args, got %d", #arg))
-end
-
-local versiondeffile = arg[1]
-local prefix = arg[2]
-
-local dev_null = iswin() and 'NUL' or '/dev/null'
-local described = io.popen('git describe --first-parent --dirty 2>'..dev_null):read('*l')
-if not described then
-  described = io.popen('git describe --first-parent --tags --always --dirty'):read('*l')
-end
-if not described then
-  io.open(versiondeffile, 'w'):write('\n')
-  die('git-describe failed, using empty include file.')
-end
-
--- `git describe` annotates the most recent tagged release; for pre-release
--- builds we append that to the dev version
-local with_prefix = prefix
-if prefix:match('-dev$') ~= nil then
-  with_prefix = prefix .. '+' .. described:gsub('^v%d+%.%d+%.%d+-', '')
-end
-
--- Read existing include file.
-local current = io.open(versiondeffile, 'r')
-if current then
-  current = current:read('*l')
-end
-
--- Write new include file, if different.
-local new = '#define NVIM_VERSION_MEDIUM "'..with_prefix..'"'
-if current ~= new then
-  io.open(versiondeffile, 'w'):write(new .. '\n')
-end

src/nvim/CMakeLists.txt

@@ -222,31 +222,17 @@ function(get_preproc_output varname iname)
   endif()
 endfunction()
 
-# Handle generating version from Git.
-set(use_git_version 0)
-if(NVIM_VERSION_MEDIUM)
-  message(STATUS "NVIM_VERSION_MEDIUM: ${NVIM_VERSION_MEDIUM}")
-elseif(EXISTS ${PROJECT_SOURCE_DIR}/.git)
-  find_program(GIT_EXECUTABLE git)
-  if(GIT_EXECUTABLE)
-    message(STATUS "Using NVIM_VERSION_MEDIUM from Git")
-    set(use_git_version 1)
-  else()
-    message(STATUS "Skipping version-string generation (cannot find git)")
-  endif()
-endif()
-if(use_git_version)
-  # Create a update_version_stamp target to update the version during build.
-  file(RELATIVE_PATH relbuild "${PROJECT_SOURCE_DIR}" "${CMAKE_BINARY_DIR}")
-  add_custom_target(update_version_stamp ALL
-    COMMAND ${LUA_PRG} scripts/update_version_stamp.lua
-      ${relbuild}/cmake.config/auto/versiondef_git.h
-      "v${NVIM_VERSION_MAJOR}.${NVIM_VERSION_MINOR}.${NVIM_VERSION_PATCH}${NVIM_VERSION_PRERELEASE}"
-    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-    BYPRODUCTS ${CMAKE_BINARY_DIR}/cmake.config/auto/versiondef_git.h)
-else()
-  file(WRITE ${CMAKE_BINARY_DIR}/cmake.config/auto/versiondef_git.h "")
-endif()
+set(NVIM_VERSION_GIT_H ${PROJECT_BINARY_DIR}/cmake.config/auto/versiondef_git.h)
+add_custom_target(update_version_stamp
+  COMMAND ${CMAKE_COMMAND}
+    -DNVIM_VERSION_MAJOR=${NVIM_VERSION_MAJOR}
+    -DNVIM_VERSION_MINOR=${NVIM_VERSION_MINOR}
+    -DNVIM_VERSION_PATCH=${NVIM_VERSION_PATCH}
+    -DNVIM_VERSION_PRERELEASE=${NVIM_VERSION_PRERELEASE}
+    -DOUTPUT=${NVIM_VERSION_GIT_H}
+    -P ${PROJECT_SOURCE_DIR}/cmake/GenerateVersion.cmake
+  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+  BYPRODUCTS ${NVIM_VERSION_GIT_H})
 
 # NVIM_GENERATED_FOR_HEADERS: generated headers to be included in headers
 # NVIM_GENERATED_FOR_SOURCES: generated headers to be included in sources
@@ -280,9 +266,9 @@ foreach(sfile ${NVIM_SOURCES}
   get_preproc_output(PREPROC_OUTPUT ${gf_i})
 
   set(depends "${HEADER_GENERATOR}" "${sfile}")
-  if(use_git_version AND "${f}" STREQUAL "version.c")
+  if("${f}" STREQUAL "version.c")
     # Ensure auto/versiondef_git.h exists after "make clean".
-    list(APPEND depends update_version_stamp)
+    list(APPEND depends "${NVIM_VERSION_GIT_H}")
   endif()
   add_custom_command(
     OUTPUT "${gf_c_h}" "${gf_h_h}"