version: Prepare for releases.

* Hide commit information from --version if we can't find any (e.g. when
  building from tarball).

To define a release in CMake, set NVIM_VERSION_PRERELEASE to "".
This will modify --version output to:

    * Show annotated Git tag instead of commit hash (NVIM_VERSION_COMMIT).
    * Hide commit date (NVIM_VERSION_BUILD).

3 files changed, 21 insertions, 12 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f7dd444105..f4e5e51bcb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -47,22 +47,27 @@ if(NOT CMAKE_BUILD_TYPE)
 endif()
 
 # Version tokens
-include(GetGitRevisionDescription)
-file(TO_NATIVE_PATH ${CMAKE_CURRENT_LIST_DIR}/.git GIT_DIR)
-get_git_head_revision(GIT_REFSPEC NVIM_VERSION_COMMIT)
-if(NOT NVIM_VERSION_COMMIT)
-  set(NVIM_VERSION_COMMIT "?")
-endif()
 set(NVIM_VERSION_MAJOR 0)
 set(NVIM_VERSION_MINOR 0)
 set(NVIM_VERSION_PATCH 0)
 set(NVIM_VERSION_PRERELEASE "-alpha")
-# TODO(justinmk): UTC time would be nice here #1071
-git_timestamp(GIT_TIMESTAMP)
-# TODO(justinmk): do not set this for "release" builds #1071
-if(GIT_TIMESTAMP)
-  set(NVIM_VERSION_BUILD "+${GIT_TIMESTAMP}")
+
+include(GetGitRevisionDescription)
+file(TO_NATIVE_PATH ${CMAKE_CURRENT_LIST_DIR}/.git GIT_DIR)
+if(NVIM_VERSION_PRERELEASE)
+  get_git_head_revision(GIT_REFSPEC NVIM_VERSION_COMMIT)
+
+  # TODO(justinmk): UTC time would be nice here #1071
+  git_timestamp(GIT_TIMESTAMP)
+  if(GIT_TIMESTAMP)
+    set(NVIM_VERSION_BUILD "+${GIT_TIMESTAMP}")
+  endif()
+else()
+  # If possible, get the Git tag for the current revision.
+  git_get_exact_tag(NVIM_VERSION_COMMIT)
+  set(NVIM_VERSION_BUILD "")
 endif()
+
 set(NVIM_VERSION_BUILD_TYPE "${CMAKE_BUILD_TYPE}")
 # NVIM_VERSION_CFLAGS set further below.
 
diff --git a/config/versiondef.h.in b/config/versiondef.h.in
index a177e599ba..bef099e55f 100644
--- a/config/versiondef.h.in
+++ b/config/versiondef.h.in
@@ -6,7 +6,7 @@
 #define NVIM_VERSION_PATCH @NVIM_VERSION_PATCH@
 #define NVIM_VERSION_PRERELEASE "@NVIM_VERSION_PRERELEASE@"
 #define NVIM_VERSION_BUILD "@NVIM_VERSION_BUILD@"
-#define NVIM_VERSION_COMMIT "@NVIM_VERSION_COMMIT@"
+#cmakedefine NVIM_VERSION_COMMIT "@NVIM_VERSION_COMMIT@"
 #define NVIM_VERSION_CFLAGS "@NVIM_VERSION_CFLAGS@"
 #define NVIM_VERSION_BUILD_TYPE "@NVIM_VERSION_BUILD_TYPE@"
 
diff --git a/src/nvim/version.c b/src/nvim/version.c
index 7cc72705b6..c8cbcf2439 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -36,7 +36,9 @@ char *Version = VIM_VERSION_SHORT;
 char *longVersion = NVIM_VERSION_LONG;
 char *longVersionWithDate = NVIM_VERSION_LONG " (compiled " __DATE__ " " __TIME__ ")";
 char *mediumVersion = NVIM_VERSION_MEDIUM;
+#ifdef NVIM_VERSION_COMMIT
 char *version_commit = "Commit: " NVIM_VERSION_COMMIT;
+#endif
 char *version_buildtype = "Build type: " NVIM_VERSION_BUILD_TYPE;
 char *version_cflags = "Compilation: " NVIM_VERSION_CFLAGS;
 
@@ -1024,7 +1026,9 @@ void list_version(void)
   // When adding features here, don't forget to update the list of
   // internal variables in eval.c!
   MSG(longVersionWithDate);
+#ifdef NVIM_VERSION_COMMIT
   MSG(version_commit);
+#endif
   MSG(version_buildtype);
   MSG(version_cflags);