4 files changed, 68 insertions, 1 deletions
diff --git a/src/buildtool/main/TARGETS b/src/buildtool/main/TARGETS
index 6e3d3c74..4fd16a86 100644
--- a/src/buildtool/main/TARGETS
+++ b/src/buildtool/main/TARGETS
@@ -19,6 +19,7 @@
     , ["src/buildtool/build_engine/target_map", "target_cache"]
     , ["src/utils/cpp", "concepts"]
     , ["src/utils/cpp", "json"]
+    , "version"
     ]
   , "stage": ["src", "buildtool", "main"]
   , "link external":
@@ -27,4 +28,27 @@
     , "then": ["-static"]
     }
   }
+, "version":
+  { "type": ["@", "rules", "CC", "library"]
+  , "arguments_config": ["SOURCE_DATE_EPOCH"]
+  , "name": ["version"]
+  , "hdrs": ["version.hpp"]
+  , "srcs": ["version.cpp"]
+  , "local defines":
+    { "type": "if"
+    , "cond": {"type": "var", "name": "SOURCE_DATE_EPOCH"}
+    , "then":
+      [ { "type": "join"
+        , "$1":
+          [ "SOURCE_DATE_EPOCH="
+          , { "type": "json_encode"
+            , "$1": {"type": "var", "name": "SOURCE_DATE_EPOCH"}
+            }
+          ]
+        }
+      ]
+    }
+  , "deps": [["@", "json", "", "json"], ["src/utils/cpp", "json"]]
+  , "stage": ["src", "buildtool", "main"]
+  }
 }
diff --git a/src/buildtool/main/main.cpp b/src/buildtool/main/main.cpp
index ba8bcb7d..d6d999ab 100644
--- a/src/buildtool/main/main.cpp
+++ b/src/buildtool/main/main.cpp
@@ -29,6 +29,7 @@
 #include "src/buildtool/logging/log_config.hpp"
 #include "src/buildtool/logging/log_sink_cmdline.hpp"
 #include "src/buildtool/logging/log_sink_file.hpp"
+#include "src/buildtool/main/version.hpp"
 #include "src/buildtool/multithreading/async_map_consumer.hpp"
 #include "src/buildtool/multithreading/task_system.hpp"
 #include "src/utils/cpp/concepts.hpp"
@@ -41,6 +42,7 @@ namespace Target = BuildMaps::Target;
 
 enum class SubCommand {
     kUnknown,
+    kVersion,
     kDescribe,
     kAnalyse,
     kBuild,
@@ -134,6 +136,8 @@ auto ParseCommandLineArguments(int argc, char const* const* argv)
     CLI::App app("just");
     app.option_defaults()->take_last();
 
+    auto* cmd_version = app.add_subcommand(
+        "version", "Print version information in JSON format.");
     auto* cmd_describe = app.add_subcommand(
         "describe", "Describe the rule generating a target.");
     auto* cmd_analyse =
@@ -152,6 +156,7 @@ auto ParseCommandLineArguments(int argc, char const* const* argv)
     app.require_subcommand(1);
 
     CommandLineArguments clargs;
+    SetupDescribeCommandArguments(cmd_version, &clargs);
     SetupDescribeCommandArguments(cmd_describe, &clargs);
     SetupAnalyseCommandArguments(cmd_analyse, &clargs);
     SetupBuildCommandArguments(cmd_build, &clargs);
@@ -169,7 +174,10 @@ auto ParseCommandLineArguments(int argc, char const* const* argv)
         std::exit(kExitFailure);
     }
 
-    if (*cmd_describe) {
+    if (*cmd_version) {
+        clargs.cmd = SubCommand::kVersion;
+    }
+    else if (*cmd_describe) {
         clargs.cmd = SubCommand::kDescribe;
     }
     else if (*cmd_analyse) {
@@ -1319,6 +1327,11 @@ auto main(int argc, char* argv[]) -> int {
     try {
         auto arguments = ParseCommandLineArguments(argc, argv);
 
+        if (arguments.cmd == SubCommand::kVersion) {
+            std::cerr << version() << std::endl;
+            return kExitSuccess;
+        }
+
         SetupLogging(arguments.common);
 #ifndef BOOTSTRAP_BUILD_TOOL
         SetupHashFunction();
diff --git a/src/buildtool/main/version.cpp b/src/buildtool/main/version.cpp
new file mode 100644
index 00000000..3bd37f2a
--- /dev/null
+++ b/src/buildtool/main/version.cpp
@@ -0,0 +1,22 @@
+#include "src/buildtool/main/version.hpp"
+
+#include "nlohmann/json.hpp"
+#include "src/utils/cpp/json.hpp"
+
+auto version() -> std::string {
+    std::size_t major = 0;
+    std::size_t minor = 1;
+    std::size_t revision = 0;
+    std::string suffix = "+devel";
+
+    nlohmann::json version_info = {{"version", {major, minor, revision}},
+                                   {"suffix", suffix}};
+
+#ifdef SOURCE_DATE_EPOCH
+    version_info["SOURCE_DATE_EPOCH"] = (std::size_t)SOURCE_DATE_EPOCH;
+#else
+    version_info["SOURCE_DATE_EPOCH"] = nullptr;
+#endif
+
+    return IndentOnlyUntilDepth(version_info, 2, 1, {});
+}
diff --git a/src/buildtool/main/version.hpp b/src/buildtool/main/version.hpp
new file mode 100644
index 00000000..c24e87e6
--- /dev/null
+++ b/src/buildtool/main/version.hpp
@@ -0,0 +1,8 @@
+#ifndef INCLUDED_SRC_BUILDOOL_MAIN_VERSION_HPP
+#define INCLUDED_SRC_BUILDOOL_MAIN_VERSION_HPP
+
+#include <string>
+
+auto version() -> std::string;
+
+#endif