Add commit information to roc versions built from source

crates/cli/Cargo.toml

@@ -2,6 +2,7 @@
 name = "roc_cli"
 description = "The Roc binary that brings together all functionality in the Roc toolset."
 default-run = "roc"
+build = "build.rs"
 
 authors.workspace = true
 edition.workspace = true
@@ -30,7 +31,13 @@ target-wasm32 = ["roc_build/target-wasm32"]
 target-x86 = ["roc_build/target-x86", "roc_repl_cli/target-x86"]
 target-x86_64 = ["roc_build/target-x86_64", "roc_repl_cli/target-x86_64"]
 
-target-all = ["target-aarch64", "target-arm", "target-x86", "target-x86_64", "target-wasm32"]
+target-all = [
+  "target-aarch64",
+  "target-arm",
+  "target-x86",
+  "target-x86_64",
+  "target-wasm32",
+]
 
 sanitizers = ["roc_build/sanitizers"]
 
@@ -93,6 +100,9 @@ parking_lot.workspace = true
 pretty_assertions.workspace = true
 serial_test.workspace = true
 
+[build-dependencies]
+chrono.workspace = true
+
 [[bench]]
 name = "time_bench"
 harness = false

crates/cli/build.rs

@@ -0,0 +1,71 @@
+use chrono::prelude::*;
+use std::fs;
+use std::process::Command;
+use std::str;
+
+fn main() {
+    // Rebuild if this build.rs file changes
+    println!("cargo:rerun-if-changed=build.rs");
+
+    // The version file is located at the root of the repository
+    let version_file_path = "../../version.txt";
+
+    // Rebuild if version file changes
+    println!("cargo:rerun-if-changed={}", version_file_path);
+
+    // Read the version file
+    let version_file_contents = fs::read_to_string(version_file_path).unwrap();
+
+    // If the version is "built-from-source", replace it with the git commit information
+    let version = match version_file_contents.trim() {
+        "built-from-source" => {
+            let git_head_file_path = "../../.git/HEAD";
+            // Rebuild if a new Git commit is made
+            println!("cargo:rerun-if-changed={}", git_head_file_path);
+
+            // Check if the .git/HEAD file exists
+            let git_head_exists = fs::metadata(git_head_file_path).is_ok();
+            if git_head_exists {
+                // Get the hash of the current commit
+                let git_describe_output = Command::new("git")
+                    .arg("describe")
+                    .arg("--always")
+                    .arg("--dirty= with additional changes") // Add a suffix if the working directory is dirty
+                    .output()
+                    .expect("Failed to execute git describe command");
+                println!("git_describe_output: {:?}", git_describe_output);
+                let git_commit_hash = str::from_utf8(&git_describe_output.stdout)
+                    .expect("Failed to parse git describe output")
+                    .trim();
+
+                // Get the datetime of the last commit
+                let git_show_output = Command::new("git")
+                    .arg("show")
+                    .arg("--no-patch")
+                    .arg("--format=%ct") // Outputting a UNIX timestamp is the only way to always use UTC
+                    .output()
+                    .expect("Failed to execute git show command");
+                println!("git_show_output: {:?}", git_show_output);
+                let git_commit_timestamp = {
+                    let timestamp = str::from_utf8(&git_show_output.stdout)
+                        .expect("Failed to parse git show output as a string")
+                        .trim()
+                        .parse::<i64>()
+                        .expect("Failed to parse timestamp as an integer");
+                    DateTime::from_timestamp(timestamp, 0)
+                        .expect("Failed to parse timestamp")
+                        .format("%Y-%m-%d %H:%M:%S")
+                };
+                format!(
+                    "built from commit {git_commit_hash}, committed at {git_commit_timestamp} UTC"
+                )
+            } else {
+                // If the .git/HEAD file does not exist, e.g. in a Nix build, use a generic message
+                "built from source".to_string()
+            }
+        }
+        _ => version_file_contents.trim().to_string(),
+    };
+    // Emit the version to a build-time environment variable
+    println!("cargo:rustc-env=ROC_VERSION={}", version);
+}

crates/cli/src/lib.rs

@@ -90,7 +90,7 @@ pub const FLAG_PP_HOST: &str = "host";
 pub const FLAG_PP_PLATFORM: &str = "platform";
 pub const FLAG_PP_DYLIB: &str = "lib";
 
-const VERSION: &str = include_str!("../../../version.txt");
+pub const VERSION: &str = env!("ROC_VERSION");
 const DEFAULT_GENERATED_DOCS_DIR: &str = "generated-docs";
 
 pub fn build_app() -> Command {
@@ -182,7 +182,7 @@ pub fn build_app() -> Command {
         PossibleValuesParser::new(Target::iter().map(Into::<&'static str>::into));
 
     Command::new("roc")
-        .version(concatcp!(VERSION, "\n"))
+        .version(VERSION)
         .about("Run the given .roc file, if there are no compilation errors.\nYou can use one of the SUBCOMMANDS below to do something else!")
         .args_conflicts_with_subcommands(true)
         .subcommand(Command::new(CMD_BUILD)

crates/cli/src/main.rs

@@ -8,7 +8,7 @@ use roc_cli::{
     CMD_RUN, CMD_TEST, CMD_VERSION, DIRECTORY_OR_FILES, FLAG_CHECK, FLAG_DEV, FLAG_LIB, FLAG_MAIN,
     FLAG_NO_COLOR, FLAG_NO_HEADER, FLAG_NO_LINK, FLAG_OUTPUT, FLAG_PP_DYLIB, FLAG_PP_HOST,
     FLAG_PP_PLATFORM, FLAG_STDIN, FLAG_STDOUT, FLAG_TARGET, FLAG_TIME, GLUE_DIR, GLUE_SPEC,
-    ROC_FILE,
+    ROC_FILE, VERSION,
 };
 use roc_docs::generate_docs_html;
 use roc_error_macros::user_error;
@@ -23,9 +23,6 @@ use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use target_lexicon::Triple;
 
-#[macro_use]
-extern crate const_format;
-
 #[global_allocator]
 static ALLOC: mimalloc::MiMalloc = mimalloc::MiMalloc;
 
@@ -364,11 +361,7 @@ fn main() -> io::Result<()> {
             Ok(format_exit_code)
         }
         Some((CMD_VERSION, _)) => {
-            print!(
-                "{}",
-                concatcp!("roc ", include_str!("../../../version.txt"))
-            );
-
+            println!("roc {}", VERSION);
             Ok(0)
         }
         _ => unreachable!(),