diff --git a/src/bootstrap/src/core/builder.rs b/src/bootstrap/src/core/builder.rs index 47420f8fe72fb..837ea276d134f 100644 --- a/src/bootstrap/src/core/builder.rs +++ b/src/bootstrap/src/core/builder.rs @@ -1683,10 +1683,24 @@ impl<'a> Builder<'a> { match mode { Mode::Std | Mode::ToolBootstrap | Mode::ToolStd => {} Mode::Rustc | Mode::Codegen | Mode::ToolRustc => { - // Build proc macros both for the host and the target + // Build proc macros both for the host and the target unless proc-macros are not + // supported by the target. if target != compiler.host && cmd_kind != Kind::Check { - cargo.arg("-Zdual-proc-macros"); - rustflags.arg("-Zdual-proc-macros"); + let error = command(self.rustc(compiler)) + .arg("--target") + .arg(target.rustc_target_arg()) + .arg("--print=file-names") + .arg("--crate-type=proc-macro") + .arg("-") + .run_capture(self) + .stderr(); + let not_supported = error + .lines() + .any(|line| line.contains("unsupported crate type `proc-macro`")); + if !not_supported { + cargo.arg("-Zdual-proc-macros"); + rustflags.arg("-Zdual-proc-macros"); + } } } }