From f334cfcdc19d868fd6c016eb1fa28e38c2e33257 Mon Sep 17 00:00:00 2001 From: David Tolnay Date: Sat, 30 Dec 2023 13:39:55 -0800 Subject: [PATCH] Do not rebuild on RUSTC_BOOTSTRAP changes on nightly compiler --- build.rs | 47 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 44 insertions(+), 3 deletions(-) diff --git a/build.rs b/build.rs index 46734ab..1792fa4 100644 --- a/build.rs +++ b/build.rs @@ -4,14 +4,51 @@ use std::path::Path; use std::process::{self, Command, Stdio}; fn main() { - println!("cargo:rerun-if-env-changed=RUSTC_BOOTSTRAP"); + let error_generic_member_access; + let consider_rustc_bootstrap; + if compile_probe(false) { + // This is a nightly or dev compiler, so it supports unstable features + // regardless of RUSTC_BOOTSTRAP. No need to rerun build script if + // RUSTC_BOOTSTRAP is changed. + error_generic_member_access = true; + consider_rustc_bootstrap = false; + } else if let Some(rustc_bootstrap) = env::var_os("RUSTC_BOOTSTRAP") { + if compile_probe(true) { + // This is a stable or beta compiler for which the user has set + // RUSTC_BOOTSTRAP to turn on unstable features. Rerun build script + // if they change it. + error_generic_member_access = true; + consider_rustc_bootstrap = true; + } else if rustc_bootstrap == "1" { + // This compiler does not support the generic member access API in + // the form that thiserror expects. No need to pay attention to + // RUSTC_BOOTSTRAP. + error_generic_member_access = false; + consider_rustc_bootstrap = false; + } else { + // This is a stable or beta compiler for which RUSTC_BOOTSTRAP is + // set to restrict the use of unstable features by this crate. + error_generic_member_access = false; + consider_rustc_bootstrap = true; + } + } else { + // Without RUSTC_BOOTSTRAP, this compiler does not support the generic + // member access API in the form that thiserror expects, but try again + // if the user turns on unstable features. + error_generic_member_access = false; + consider_rustc_bootstrap = true; + } - if compile_probe() { + if error_generic_member_access { println!("cargo:rustc-cfg=error_generic_member_access"); } + + if consider_rustc_bootstrap { + println!("cargo:rerun-if-env-changed=RUSTC_BOOTSTRAP"); + } } -fn compile_probe() -> bool { +fn compile_probe(rustc_bootstrap: bool) -> bool { if env::var_os("RUSTC_STAGE").is_some() { // We are running inside rustc bootstrap. This is a highly non-standard // environment with issues such as: @@ -37,6 +74,10 @@ fn compile_probe() -> bool { Command::new(rustc) }; + if !rustc_bootstrap { + cmd.env_remove("RUSTC_BOOTSTRAP"); + } + cmd.stderr(Stdio::null()) .arg("--edition=2018") .arg("--crate-name=thiserror")