Write entries for clang modules in explicit swift module map.

PiperOrigin-RevId: 542275780

swift/internal/explicit_module_map_file.bzl

@@ -37,18 +37,37 @@ def write_explicit_swift_module_map_file(
     module_descriptions = []
 
     for module_context in module_contexts:
-        if not module_context.swift:
-            continue
-
-        swift_context = module_context.swift
+        # Set attributes that are applicable to a swift module entry or a
+        # clang module entry
         module_description = {"moduleName": module_context.name}
-        if swift_context.swiftmodule:
-            module_description["modulePath"] = swift_context.swiftmodule.path
         if module_context.is_system:
             module_description["isSystem"] = module_context.is_system
         if module_context.is_framework:
             module_description["isFramework"] = module_context.is_framework
-        module_descriptions.append(module_description)
+
+        # Append a swift moule entry if available
+        if module_context.swift:
+            swift_context = module_context.swift
+            swift_description = dict(module_description)
+            if swift_context.swiftmodule:
+                swift_description["modulePath"] = swift_context.swiftmodule.path
+            module_descriptions.append(swift_description)
+
+        # Append a clang module entry if available
+        if module_context.clang:
+            clang_context = module_context.clang
+            if not clang_context.module_map and not clang_context.precompiled_module:
+                # One of these must be set for our explicit clang module entry
+                # to be valid
+                continue
+            clang_description = dict(module_description)
+            if clang_context.module_map:
+                # If path is not an attribute of `module_map`, then `module_map` is a string and we use it as our path.
+                clang_description["clangModuleMapPath"] = getattr(clang_context.module_map, "path", clang_context.module_map)
+            if clang_context.precompiled_module:
+                clang_description["clangModulePath"] = clang_context.precompiled_module.path
+
+            module_descriptions.append(clang_description)
 
     actions.write(
         content = json.encode(module_descriptions),