[nix] move linting into derivation

This commit move code linting to derivation, so we can force developer
to format their code at local build.

Signed-off-by: Avimitin <[email protected]>

build.sc

@@ -16,6 +16,9 @@ import $file.dependencies.`berkeley-hardfloat`.common
 import $file.dependencies.rvdecoderdb.common
 import $file.common
 
+// Required for scalafmt to recognize which file to format
+def buildSources = T.sources(os.pwd / "build.sc")
+
 object v {
   val scala    = "2.13.14"
   val mainargs = ivy"com.lihaoyi::mainargs:0.5.0"
@@ -150,7 +153,7 @@ trait T1Emulator extends millbuild.common.T1EmulatorModule with ScalafmtModule {
   def chiselIvy       = None
 }
 
-object rocketemu     extends RocketEmulator
+object rocketemu extends RocketEmulator
 
 trait RocketEmulator extends millbuild.common.RocketEmulatorModule with ScalafmtModule {
   def scalaVersion = T(v.scala)

difftest/default.nix

@@ -1,5 +1,6 @@
 { lib
 , rustPlatform
+, rustfmt
 , libspike
 , libspike_interfaces
 , rtlDesignMetadata
@@ -31,9 +32,21 @@ rustPlatform.buildRustPackage {
       ./dpi_t1rocket
       ./Cargo.lock
       ./Cargo.toml
+      ./.rustfmt.toml
     ];
   };
 
+  nativeBuildInputs = [
+    rustfmt
+  ];
+
+  postConfigure = ''
+    if ! cargo fmt --check; then
+      echo "Please run 'cd difftest && cargo fmt' before building emulator!" >&2
+      exit 1
+    fi
+  '';
+
   buildFeatures = [ ] ++ lib.optionals (lib.hasPrefix "dpi" moduleType) [ "dpi_common/${emuType}" ] ++ lib.optionals enableTrace [ "dpi_common/trace" ];
   buildAndTestSubdir = "./${moduleType}";
 

nix/pkgs/mill-builder.nix

@@ -23,6 +23,14 @@ let
 
       mill -i __.prepareOffline
       mill -i __.scalaCompilerClasspath
+
+      # mill doesn't put scalafmt version into module ivy deps.
+      # It downloads scalafmt only when checkFormat/reformat is explicitly trigger.
+      # And we don't want to wait too long for a dependencies task, so here is the solution:
+      # "checkFormat" the "build.sc" file so that mill will download scalafmt for us,
+      # and we don't need to wait too long for formatting.
+      mill -i mill.scalalib.scalafmt.ScalafmtModule/checkFormatAll buildSources
+
       runHook postBuild
     '';
 

nix/t1/mill-modules.nix

@@ -33,6 +33,7 @@ let
         ./../../t1rocket/src
         ./../../t1rocketemu/src
         ./../../rocketemu/src
+        ./../../.scalafmt.conf
       ];
     };
 
@@ -43,9 +44,10 @@ let
         fileset = unions [
           ./../../build.sc
           ./../../common.sc
+          ./../../.scalafmt.conf
         ];
       };
-      millDepsHash = "sha256-ZK3m6VKG3PChoj6U2b6bVd+Z2/xkZrPxqaLRVvj7QgQ=";
+      millDepsHash = "sha256-gBxEO6pGD0A1RxZW2isjPcHDf+b9Sr++7eq6Ezngiio=";
       nativeBuildInputs = [ dependencies.setupHook ];
     };
 
@@ -80,11 +82,42 @@ let
 
     outputs = [ "out" "configgen" "elaborator" "t1package" ];
 
+    # Check code format before starting build, so that we can enforce all developer run reformat before build.
+    configurePhase = ''
+      runHook preConfigure
+
+      _targetsToCheck=(
+        "configgen"
+        "elaborator"
+        "omreader"
+        "omreaderlib"
+        "rocketemu"
+        "rocketv"
+        "t1"
+        "t1emu"
+        "t1rocket"
+        "t1rocketemu"
+      )
+      for _t in ''${_targetsToCheck[@]}; do
+        if ! mill -i "$_t".checkFormat; then
+          echo "[ERROR] Please run 'mill -i $_t.reformat' before elaborate!" >&2
+          exit 1
+        fi
+      done
+      unset _targetsToCheck
+
+      runHook postConfigure
+    '';
+
     buildPhase = ''
+      runHook preBuild
+
       mill -i '__.assembly'
 
       mill -i t1package.sourceJar
       mill -i t1package.chiselPluginJar
+
+      runHook postBuild
     '';
 
     installPhase = ''