Add support for -Xcontext-receivers (#1117)

* Add support for -Xcontext-receivers

* Docs

Author: Bencodes

docs/kotlin.md

@@ -397,10 +397,10 @@ kt_javac_options(<a href="#kt_javac_options-name">name</a>, <a href="#kt_javac_o
 ## kt_kotlinc_options
 
 kt_kotlinc_options(<a href="#kt_kotlinc_options-name">name</a>, <a href="#kt_kotlinc_options-include_stdlibs">include_stdlibs</a>, <a href="#kt_kotlinc_options-java_parameters">java_parameters</a>, <a href="#kt_kotlinc_options-jvm_target">jvm_target</a>, <a href="#kt_kotlinc_options-warn">warn</a>,
-                   <a href="#kt_kotlinc_options-x_allow_result_return_type">x_allow_result_return_type</a>, <a href="#kt_kotlinc_options-x_backend_threads">x_backend_threads</a>, <a href="#kt_kotlinc_options-x_emit_jvm_type_annotations">x_emit_jvm_type_annotations</a>,
-                   <a href="#kt_kotlinc_options-x_enable_incremental_compilation">x_enable_incremental_compilation</a>, <a href="#kt_kotlinc_options-x_explicit_api_mode">x_explicit_api_mode</a>, <a href="#kt_kotlinc_options-x_inline_classes">x_inline_classes</a>,
-                   <a href="#kt_kotlinc_options-x_jvm_default">x_jvm_default</a>, <a href="#kt_kotlinc_options-x_lambdas">x_lambdas</a>, <a href="#kt_kotlinc_options-x_multi_platform">x_multi_platform</a>, <a href="#kt_kotlinc_options-x_no_call_assertions">x_no_call_assertions</a>, <a href="#kt_kotlinc_options-x_no_optimize">x_no_optimize</a>,
-                   <a href="#kt_kotlinc_options-x_no_optimized_callable_references">x_no_optimized_callable_references</a>, <a href="#kt_kotlinc_options-x_no_param_assertions">x_no_param_assertions</a>,
+                   <a href="#kt_kotlinc_options-x_allow_result_return_type">x_allow_result_return_type</a>, <a href="#kt_kotlinc_options-x_backend_threads">x_backend_threads</a>, <a href="#kt_kotlinc_options-x_context_receivers">x_context_receivers</a>,
+                   <a href="#kt_kotlinc_options-x_emit_jvm_type_annotations">x_emit_jvm_type_annotations</a>, <a href="#kt_kotlinc_options-x_enable_incremental_compilation">x_enable_incremental_compilation</a>, <a href="#kt_kotlinc_options-x_explicit_api_mode">x_explicit_api_mode</a>,
+                   <a href="#kt_kotlinc_options-x_inline_classes">x_inline_classes</a>, <a href="#kt_kotlinc_options-x_jvm_default">x_jvm_default</a>, <a href="#kt_kotlinc_options-x_lambdas">x_lambdas</a>, <a href="#kt_kotlinc_options-x_multi_platform">x_multi_platform</a>, <a href="#kt_kotlinc_options-x_no_call_assertions">x_no_call_assertions</a>,
+                   <a href="#kt_kotlinc_options-x_no_optimize">x_no_optimize</a>, <a href="#kt_kotlinc_options-x_no_optimized_callable_references">x_no_optimized_callable_references</a>, <a href="#kt_kotlinc_options-x_no_param_assertions">x_no_param_assertions</a>,
                    <a href="#kt_kotlinc_options-x_no_receiver_assertions">x_no_receiver_assertions</a>, <a href="#kt_kotlinc_options-x_no_source_debug_extension">x_no_source_debug_extension</a>, <a href="#kt_kotlinc_options-x_optin">x_optin</a>, <a href="#kt_kotlinc_options-x_report_perf">x_report_perf</a>,
                    <a href="#kt_kotlinc_options-x_sam_conversions">x_sam_conversions</a>, <a href="#kt_kotlinc_options-x_skip_prerelease_check">x_skip_prerelease_check</a>, <a href="#kt_kotlinc_options-x_use_fir_lt">x_use_fir_lt</a>, <a href="#kt_kotlinc_options-x_use_k2">x_use_k2</a>)
 
@@ -420,6 +420,7 @@ kt_kotlinc_options(<a href="#kt_kotlinc_options-name">name</a>, <a href="#kt_kot
 |<a id="kt_kotlinc_options-warn"></a>warn |  Control warning behaviour.   | String | optional | "report" |
 |<a id="kt_kotlinc_options-x_allow_result_return_type"></a>x_allow_result_return_type |  Enable kotlin.Result as a return type   | Boolean | optional | False |
 |<a id="kt_kotlinc_options-x_backend_threads"></a>x_backend_threads |  When using the IR backend, run lowerings by file in N parallel threads. 0 means use a thread per processor core. Default value is 1.   | Integer | optional | 1 |
+|<a id="kt_kotlinc_options-x_context_receivers"></a>x_context_receivers |  Enable experimental context receivers.   | Boolean | optional | False |
 |<a id="kt_kotlinc_options-x_emit_jvm_type_annotations"></a>x_emit_jvm_type_annotations |  Basic support for type annotations in JVM bytecode.   | Boolean | optional | False |
 |<a id="kt_kotlinc_options-x_enable_incremental_compilation"></a>x_enable_incremental_compilation |  Enable incremental compilation   | Boolean | optional | False |
 |<a id="kt_kotlinc_options-x_explicit_api_mode"></a>x_explicit_api_mode |  Enable explicit API mode for Kotlin libraries.   | String | optional | "off" |

src/main/starlark/core/options/opts.kotlinc.bzl

@@ -66,6 +66,17 @@ _KOPTS_ALL = {
             True: ["-Xskip-prerelease-check"],
         },
     ),
+    "x_context_receivers": struct(
+        flag = "-Xcontext-receivers",
+        args = dict(
+            default = False,
+            doc = "Enable experimental context receivers.",
+        ),
+        type = attr.bool,
+        value_to_flag = {
+            True: ["-Xcontext-receivers"],
+        },
+    ),
     "x_inline_classes": struct(
         flag = "-Xinline-classes",
         args = dict(