[fix] collect scalac options from toolchain

CHANGELOG.md

@@ -4,9 +4,15 @@
 
 
 ## [Unreleased]
+
+### Fixes 🛠️
+- Collect scalac options from the toolchain
+   | [#433](https://github.com/JetBrains/bazel-bsp/pull/433)
+
 ### Performance
 -  Reduce peak memory footprint
    | [#428](https://github.com/JetBrains/bazel-bsp/pull/428)
+
 ## [2.7.1]
 
 ### Fixes 🛠️

install/src/main/resources/aspects.bzl

@@ -143,7 +143,32 @@ def extract_scala_info(target, ctx, output_groups):
     if not provider:
         return None
 
-    scalac_opts = getattr(ctx.rule.attr, "scalacopts", [])
+    # proper solution, but it requires adding scala_toolchain to the aspect
+    # SCALA_TOOLCHAIN = "@io_bazel_rules_scala//scala:toolchain_type"
+    # check of _scala_toolchain is necessary, because SCALA_TOOLCHAIN will always be present
+    # if hasattr(ctx.rule.attr, "_scala_toolchain"):
+    #    common_scalac_opts = ctx.toolchains[SCALA_TOOLCHAIN].scalacopts
+    # else:
+    #    common_scalac_opts = []
+    # scalac_opts = common_scalac_opts + getattr(ctx.rule.attr, "scalacopts", [])
+
+    scalac_opts = []
+
+    # don't bother inspecting non-scala targets
+    if hasattr(ctx.rule.attr, "_scala_toolchain"):
+        for action in target.actions:
+            if action.mnemonic == "Scalac":
+                found_scalac_opts = False
+                for arg in action.argv:
+                    if arg == "--ScalacOpts":
+                        found_scalac_opts = True
+                    elif found_scalac_opts:
+                        # Next worker option appeared.
+                        # Currently --ScalacOpts is the last one, but just in case
+                        if arg.startswith("--"):
+                            break
+                        scalac_opts.append(arg)
+                break
 
     scala_info = struct(
         scalac_opts = scalac_opts,