Remove experimental_toolchain_generated_sysroot flag

Author: Vinh Tran

examples/.bazelrc

@@ -21,7 +21,3 @@ common --noenable_bzlmod
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True
-

examples/android/.bazelrc

@@ -8,6 +8,3 @@ build --fat_apk_cpu=arm64-v8a
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/bzlmod/hello_world/.bazelrc

@@ -4,6 +4,3 @@ startup --windows_enable_symlinks
 build:windows --enable_runfiles
 
 build --experimental_enable_bzlmod
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/crate_universe/.bazelrc

@@ -26,5 +26,3 @@ common --noenable_bzlmod
 # settings for local development.
 try-import %workspace%/user.bazelrc
 
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/crate_universe/cargo_aliases/.bazelrc

@@ -20,6 +20,3 @@ common --noenable_bzlmod
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/crate_universe/cargo_remote/.bazelrc

@@ -20,6 +20,3 @@ common --noenable_bzlmod
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/crate_universe/cargo_workspace/.bazelrc

@@ -20,6 +20,3 @@ common --noenable_bzlmod
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/crate_universe/multi_package/.bazelrc

@@ -20,6 +20,3 @@ common --noenable_bzlmod
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/crate_universe/no_cargo_manifests/.bazelrc

@@ -20,6 +20,3 @@ common --noenable_bzlmod
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/crate_universe_unnamed/.bazelrc

@@ -21,6 +21,3 @@ common --noenable_bzlmod
 # This import should always be last to allow users to override
 # settings for local development.
 try-import %workspace%/user.bazelrc
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/ios/.bazelrc

@@ -11,6 +11,3 @@ build --host_crosstool_top=@local_config_apple_cc//:toolchain
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/ios_build/.bazelrc

@@ -11,6 +11,3 @@ build --host_crosstool_top=@local_config_apple_cc//:toolchain
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

examples/zig_cross_compiling/.bazelrc

@@ -8,6 +8,3 @@ build --incompatible_enable_cc_toolchain_resolution
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_rust/issues/2181
 common --noenable_bzlmod
-
-# Set --sysroot to stdlibs directory generated by rust_toolchain
-common --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot=True

rust/settings/BUILD.bazel

@@ -1,6 +1,5 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
 load("@bazel_skylib//rules:common_settings.bzl", "bool_flag", "string_flag")
-load(":incompatible.bzl", "incompatible_flag")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -64,10 +63,3 @@ bzl_library(
     name = "bzl_lib",
     srcs = glob(["**/*.bzl"]),
 )
-
-# A flag to set rustc --sysroot flag to the sysroot generated by rust_toolchain
-incompatible_flag(
-    name = "experimental_toolchain_generated_sysroot",
-    build_setting_default = False,
-    issue = "https://github.com/bazelbuild/rules_rust/issues/2039",
-)

rust/toolchain.bzl

@@ -16,7 +16,6 @@ load(
     "find_cc_toolchain",
     "make_static_lib_symlink",
 )
-load("//rust/settings:incompatible.bzl", "IncompatibleFlagInfo")
 
 rust_analyzer_toolchain = _rust_analyzer_toolchain
 rustfmt_toolchain = _rustfmt_toolchain
@@ -540,9 +539,7 @@ def _rust_toolchain_impl(ctx):
 
     # Override "rustc --print sysroot" with sysroot generated by `_generate_sysroot`
     # in this rule implementation
-    rustc_flags = ctx.attr.extra_rustc_flags
-    if ctx.attr._experimental_toolchain_generated_sysroot[IncompatibleFlagInfo].enabled == True:
-        rustc_flags = ["--sysroot=" + sysroot_path] + rustc_flags
+    rustc_flags = ["--sysroot=" + sysroot_path] + ctx.attr.extra_rustc_flags
 
     # Variables for make variable expansion
     make_variables = {
@@ -794,13 +791,6 @@ rust_toolchain = rule(
         "_cc_toolchain": attr.label(
             default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
         ),
-        "_experimental_toolchain_generated_sysroot": attr.label(
-            default = Label("//rust/settings:experimental_toolchain_generated_sysroot"),
-            doc = (
-                "Label to a boolean build setting that lets the rule knows wheter to set --sysroot to rustc" +
-                "This flag is only relevant when used together with --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot."
-            ),
-        ),
         "_experimental_use_coverage_metadata_files": attr.label(
             default = Label("//rust/settings:experimental_use_coverage_metadata_files"),
         ),

test/toolchain/toolchain_test.bzl

@@ -52,7 +52,6 @@ toolchain_adds_rustc_flags_test = analysistest.make(
     _toolchain_adds_rustc_flags_impl,
     config_settings = {
         str(Label("//:extra_rustc_flags")): [CONFIG_FLAG],
-        str(Label("//rust/settings:experimental_toolchain_generated_sysroot")): True,
     },
 )