From 965b289484d41255c707afd707e21ec193dc4793 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jalil=20David=20Salam=C3=A9=20Messina?=
 <jalil.salame@gmail.com>
Date: Sun, 16 Jun 2024 13:50:55 +0200
Subject: [PATCH] [feat] package: reduce rebuilds

Only copy Rust sources to reduce rebuilds if only nix stuff (or CI)
changed.
---
 .cargo/config |  1 +
 default.nix   | 27 ++++++++++++++++++++++-----
 2 files changed, 23 insertions(+), 5 deletions(-)
 create mode 120000 .cargo/config

diff --git a/.cargo/config b/.cargo/config
new file mode 120000
index 0000000..ab8b69c
--- /dev/null
+++ b/.cargo/config
@@ -0,0 +1 @@
+config.toml
\ No newline at end of file
diff --git a/default.nix b/default.nix
index 4cd4398..a374ee4 100644
--- a/default.nix
+++ b/default.nix
@@ -6,13 +6,30 @@
   cargoToml = readToml ./Cargo.toml;
   pname = cargoToml.package.name;
   inherit (cargoToml.package) version description;
+  src = lib.cleanSourceWith {
+    src = ./.;
+    name = "${pname}-source";
+    # Adapted from <https://github.com/ipetkov/crane/blob/master/lib/filterCargoSources.nix>
+    # no need to pull in crane for just this
+    filter = orig_path: type: let
+      path = toString orig_path;
+      base = baseNameOf path;
+      parentDir = baseNameOf (dirOf path);
+      matchesSuffix = lib.any (suffix: lib.hasSuffix suffix base) [
+        # Rust sources
+        ".rs"
+        # TOML files are often used to configure cargo based tools (e.g. .cargo/config.toml)
+        ".toml"
+      ];
+      isCargoLock = base == "Cargo.lock";
+      # .cargo/config.toml is captured above
+      isOldStyleCargoConfig = parentDir == ".cargo" && base == "config";
+    in
+      type == "directory" || matchesSuffix || isCargoLock || isOldStyleCargoConfig;
+  };
 in
   rustPlatform.buildRustPackage {
-    inherit pname version;
-    src = builtins.path {
-      path = ./.;
-      name = "${pname}-source";
-    };
+    inherit pname version src;
     cargoLock.lockFile = ./Cargo.lock;
     useNextest = true;