Backout D48975392

Summary: This was a hack anyway, and it turns out to be broken for build script. Rest of the stack does it better

Reviewed By: capickett

Differential Revision: D51461804

fbshipit-source-id: 054e99756167bfe1c9a9cf749bb439afdff36376

prelude/rust/cargo_buildscript.bzl

@@ -47,7 +47,7 @@ def _cargo_buildscript_impl(ctx: AnalysisContext) -> list[Provider]:
     env["CARGO_PKG_NAME"] = ctx.attrs.package_name
     env["CARGO_PKG_VERSION"] = ctx.attrs.version
     env["OUT_DIR"] = out_dir.as_output()
-    env["RUSTC"] = cmd_args(toolchain_info.compiler_standalone).relative_to(cwd)
+    env["RUSTC"] = cmd_args(toolchain_info.compiler).relative_to(cwd)
     env["RUSTC_LINKER"] = "/bin/false"
     env["RUST_BACKTRACE"] = "1"
     env["TARGET"] = toolchain_info.rustc_target_triple

prelude/rust/rust_toolchain.bzl

@@ -65,9 +65,6 @@ rust_toolchain_attrs = {
     "failure_filter": provider_field(bool, default = False),
     # The Rust compiler (rustc)
     "compiler": provider_field(RunInfo | None, default = None),
-    # A Rust compiler that can be used "standalone", without special settings
-    # from Rust rules (e.g. this keeps the default sysroot).
-    "compiler_standalone": provider_field(RunInfo | None, default = None),
     # Rust documentation extractor (rustdoc)
     "rustdoc": provider_field(RunInfo | None, default = None),
     # Clippy (linter) version of the compiler

prelude/toolchains/rust.bzl

@@ -42,7 +42,6 @@ def _system_rust_toolchain_impl(ctx):
             clippy_driver = RunInfo(args = ["clippy-driver"]),
             clippy_toml = ctx.attrs.clippy_toml[DefaultInfo].default_outputs[0] if ctx.attrs.clippy_toml else None,
             compiler = RunInfo(args = ["rustc"]),
-            compiler_standalone = RunInfo(args = ["rustc"]),
             concat_tool = ctx.attrs.concat_tool[RunInfo],
             default_edition = ctx.attrs.default_edition,
             deny_lints = ctx.attrs.deny_lints,