Fix path mapping from #99

mojo/mojo_import.bzl

@@ -9,8 +9,11 @@ def _mojo_import_impl(ctx):
     return [
         DefaultInfo(files = depset(mojo_deps, transitive = [transitive_mojodeps])),
         MojoInfo(
-            import_paths = depset([pkg.dirname for pkg in mojo_deps], transitive = [import_paths]),
-            mojodeps = depset([pkg for pkg in mojo_deps], transitive = [transitive_mojodeps]),
+            import_paths = depset(
+                [struct(package = pkg, import_path = ".") for pkg in mojo_deps],
+                transitive = [import_paths],
+            ),
+            mojodeps = depset(mojo_deps, transitive = [transitive_mojodeps]),
         ),
     ]
 

mojo/mojo_library.bzl

@@ -3,7 +3,7 @@ other Mojo targets."""
 
 load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
 load("//mojo:providers.bzl", "MojoInfo")
-load("//mojo/private:utils.bzl", "MOJO_EXTENSIONS", "collect_mojoinfo", "is_exec_config")
+load("//mojo/private:utils.bzl", "MOJO_EXTENSIONS", "collect_mojoinfo", "format_import", "is_exec_config")
 
 def _format_include(arg):
     return ["-I", arg.dirname]
@@ -42,7 +42,7 @@ def _mojo_library_implementation(ctx):
         output_group_kwargs["mojo_fixits"] = depset([fixits_file])
         args.add("--experimental-export-fixit", fixits_file)
 
-    file_args.add_all(transitive_mojodeps, map_each = _format_include)
+    file_args.add_all(import_paths, map_each = format_import)
     file_args.add(root_directory)
     ctx.actions.run(
         executable = mojo_toolchain.mojo,
@@ -68,15 +68,17 @@ def _mojo_library_implementation(ctx):
     for target in ctx.attr.data:
         transitive_runfiles.append(target[DefaultInfo].default_runfiles)
 
-    import_path = mojo_precmp_file.dirname + "/" + ctx.attr.import_path
-
     return [
         DefaultInfo(
             files = depset([mojo_precmp_file]),
             runfiles = ctx.runfiles(ctx.files.data).merge_all(transitive_runfiles),
         ),
         MojoInfo(
-            import_paths = depset([import_path], transitive = [import_paths]),
+            # Passed through as a File + string combo so that it can be path mapped later.
+            import_paths = depset(
+                [struct(package = mojo_precmp_file, import_path = ctx.attr.import_path)],
+                transitive = [import_paths],
+            ),
             mojodeps = depset([mojo_precmp_file], transitive = [transitive_mojodeps]),
         ),
         OutputGroupInfo(**output_group_kwargs),

mojo/private/mojo_binary_test.bzl

@@ -9,7 +9,7 @@ load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("@rules_python//python:py_info.bzl", "PyInfo")
 load("//mojo:providers.bzl", "MojoInfo")
 load(":transitions.bzl", "python_version_transition")
-load(":utils.bzl", "MOJO_EXTENSIONS", "collect_mojoinfo", "is_exec_config")
+load(":utils.bzl", "MOJO_EXTENSIONS", "collect_mojoinfo", "format_import", "is_exec_config")
 
 _PYTHON_TOOLCHAIN_TYPE = "@rules_python//python:toolchain_type"
 _ATTRS = {
@@ -93,9 +93,6 @@ def _find_main(name, srcs, main):
 def _format_include(arg):
     return ["-I", arg.dirname]
 
-def _add_include(arg):
-    return ["-I", arg]
-
 def _mojo_binary_test_implementation(ctx, *, shared_library = False):
     cc_toolchain = find_cpp_toolchain(ctx)
     mojo_toolchain = ctx.exec_groups["mojo_compile"].toolchains["//:toolchain_type"].mojo_toolchain_info
@@ -121,7 +118,7 @@ def _mojo_binary_test_implementation(ctx, *, shared_library = False):
 
     all_deps = ctx.attr.deps + mojo_toolchain.implicit_deps + ([ctx.attr._link_extra_lib] if ctx.attr._link_extra_lib else [])
     transitive_includes, transitive_mojodeps = collect_mojoinfo(all_deps)
-    args.add_all(transitive_includes, map_each = _add_include)
+    args.add_all(transitive_includes, map_each = format_import)
 
     # NOTE: Argument order:
     # 1. Basic functional arguments

mojo/private/utils.bzl

@@ -1,6 +1,7 @@
 """Helpers internal to rules_mojo."""
 
 load("@bazel_features//:features.bzl", "bazel_features")
+load("@bazel_skylib//lib:paths.bzl", "paths")
 load("//mojo:providers.bzl", "MojoInfo")
 
 MOJO_EXTENSIONS = ("mojo",)
@@ -12,7 +13,9 @@ def collect_mojoinfo(deps):
         deps: A list of dependencies to collect MojoInfo from.
 
     Returns:
-        A single MojoInfo object with the combined data.
+        A tuple (imports, mojodeps) of two depsets combining every MojoInfo in
+        deps: `imports` holds struct(package, import_path) entries for building
+        -I flags, `mojodeps` holds the precompiled mojo Files for action inputs.
     """
     import_paths = []
     mojodeps = []
@@ -24,6 +27,9 @@ def collect_mojoinfo(deps):
 
     return depset(transitive = import_paths), depset(transitive = mojodeps)
 
+def format_import(dep):
+    return ["-I", paths.normalize(paths.join(dep.package.dirname, dep.import_path))]
+
 def is_exec_config(ctx):
     """Determines whether the current configuration is an exec configuration.
 

mojo/providers.bzl

@@ -3,7 +3,7 @@
 MojoInfo = provider(
     doc = "Information about how to build a Mojo target.",
     fields = {
-        "import_paths": "Directories that should be passed with -I to mojo",
+        "import_paths": "Depset of struct(package = File, import_path = str). Each element is a mojoc file paired with its relative import path.",
         "mojodeps": "The precompiled mojo files required by the target",
     },
 )