stage2: SemVer compliance for development builds

This matches the behavior of CMake builds. These changes should have
been in PR #6509, but were missed.

1 files changed, 34 insertions, 16 deletions

diff --git a/build.zig b/build.zig
index bef3b3b58f..197dd0bbed 100644
--- a/build.zig
+++ b/build.zig
@@ -11,7 +11,7 @@ const fs = std.fs;
 const InstallDirectoryOptions = std.build.InstallDirectoryOptions;
 const assert = std.debug.assert;
 
-const zig_version = std.builtin.Version{ .major = 0, .minor = 7, .patch = 1 };
+const zig_version = std.builtin.Version{ .major = 0, .minor = 8, .patch = 0 };
 
 pub fn build(b: *Builder) !void {
     b.setPreferredReleaseMode(.ReleaseFast);
@@ -227,24 +227,42 @@ pub fn build(b: *Builder) !void {
         const version_string = b.fmt("{}.{}.{}", .{ zig_version.major, zig_version.minor, zig_version.patch });
 
         var code: u8 = undefined;
-        const git_sha_untrimmed = b.execAllowFail(&[_][]const u8{
-            "git",    "-C",          b.build_root,     "name-rev", "HEAD",
-            "--tags", "--name-only", "--no-undefined", "--always",
+        const git_describe_untrimmed = b.execAllowFail(&[_][]const u8{
+            "git", "-C", b.build_root, "describe", "--match", "*.*.*", "--tags",
         }, &code, .Ignore) catch {
             break :v version_string;
         };
-        const git_sha_trimmed = mem.trim(u8, git_sha_untrimmed, " \n\r");
-
-        // This will look like e.g. "0.7.0^0" for a tag commit.
-        if (mem.endsWith(u8, git_sha_trimmed, "^0")) {
-            const git_ver_string = git_sha_trimmed[0 .. git_sha_trimmed.len - 2];
-            if (!mem.eql(u8, git_ver_string, version_string)) {
-                std.debug.print("Expected git tag '{}', found '{}'\n", .{ version_string, git_ver_string });
-                std.process.exit(1);
-            }
-            break :v b.fmt("{}", .{version_string});
-        } else {
-            break :v b.fmt("{}+{}", .{ version_string, git_sha_trimmed });
+        const git_describe = mem.trim(u8, git_describe_untrimmed, " \n\r");
+
+        switch (mem.count(u8, git_describe, "-")) {
+            0 => {
+                // Tagged release version (e.g. 0.7.0).
+                if (!mem.eql(u8, git_describe, version_string)) {
+                    std.debug.print("Zig version '{}' does not match Git tag '{}'\n", .{ version_string, git_describe });
+                    std.process.exit(1);
+                }
+                break :v version_string;
+            },
+            2 => {
+                // Untagged development build (e.g. 0.7.0-684-gbbe2cca1a).
+                var it = mem.split(git_describe, "-");
+                const tagged_ancestor = it.next() orelse unreachable;
+                const commit_height = it.next() orelse unreachable;
+                const commit_id = it.next() orelse unreachable;
+
+                const ancestor_ver = try std.builtin.Version.parse(tagged_ancestor);
+                if (zig_version.order(ancestor_ver) != .gt) {
+                    std.debug.print("Zig version '{}' must be greater than tagged ancestor '{}'\n", .{ zig_version, ancestor_ver });
+                    std.process.exit(1);
+                }
+
+                // The version is reformatted in accordance with the https://semver.org specification.
+                break :v b.fmt("{}-dev.{}+{}", .{ version_string, commit_height, commit_id });
+            },
+            else => {
+                std.debug.print("Failed to parse `git describe` output: {}\n", .{git_describe});
+                break :v version_string;
+            },
         }
     };
     exe.addBuildOption([:0]const u8, "version", try b.allocator.dupeZ(u8, version));