diff options
Diffstat (limited to 'build.rs')
| -rw-r--r-- | build.rs | 134 |
1 files changed, 85 insertions, 49 deletions
@@ -1,9 +1,7 @@ -#![allow(clippy::option_if_let_else)] - use std::env; -use std::fs; +use std::ffi::OsString; use std::path::Path; -use std::process::{Command, ExitStatus, Stdio}; +use std::process::{self, Command, Stdio}; use std::str; #[cfg(all(feature = "backtrace", not(feature = "std")))] @@ -11,45 +9,53 @@ compile_error! { "`backtrace` feature without `std` feature is not supported" } -// This code exercises the surface area that we expect of the Error generic -// member access API. If the current toolchain is able to compile it, then -// anyhow is able to provide backtrace support. -const PROBE: &str = r#" - #![feature(error_generic_member_access)] - - use std::backtrace::Backtrace; - use std::error::{self, Error, Request}; - use std::fmt::{self, Debug, Display}; - - struct MyError(Thing); - struct Thing; - - impl Debug for MyError { - fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result { - unimplemented!() - } - } - - impl Display for MyError { - fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result { - unimplemented!() +fn main() { + let mut error_generic_member_access = false; + if cfg!(feature = "std") { + println!("cargo:rerun-if-changed=build/probe.rs"); + + 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 anyhow 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 anyhow expects, but + // try again if the user turns on unstable features. + error_generic_member_access = false; + consider_rustc_bootstrap = true; } - } - impl Error for MyError { - fn provide<'a>(&'a self, request: &mut Request<'a>) { - request.provide_ref(&self.0); + if error_generic_member_access { + println!("cargo:rustc-cfg=std_backtrace"); + println!("cargo:rustc-cfg=error_generic_member_access"); } - } - const _: fn(&dyn Error) -> Option<&Backtrace> = |err| error::request_ref::<Backtrace>(err); -"#; - -fn main() { - if cfg!(feature = "std") { - match compile_probe() { - Some(status) if status.success() => println!("cargo:rustc-cfg=backtrace"), - _ => {} + if consider_rustc_bootstrap { + println!("cargo:rerun-if-env-changed=RUSTC_BOOTSTRAP"); } } @@ -59,15 +65,29 @@ fn main() { }; if rustc < 51 { + // core::ptr::addr_of + // https://blog.rust-lang.org/2021/03/25/Rust-1.51.0.html#stabilized-apis println!("cargo:rustc-cfg=anyhow_no_ptr_addr_of"); } if rustc < 52 { + // core::fmt::Arguments::as_str + // https://blog.rust-lang.org/2021/05/06/Rust-1.52.0.html#stabilized-apis println!("cargo:rustc-cfg=anyhow_no_fmt_arguments_as_str"); + + // #![deny(unsafe_op_in_unsafe_fn)] + // https://github.com/rust-lang/rust/issues/71668 + println!("cargo:rustc-cfg=anyhow_no_unsafe_op_in_unsafe_fn_lint"); + } + + if !error_generic_member_access && cfg!(feature = "std") && rustc >= 65 { + // std::backtrace::Backtrace + // https://blog.rust-lang.org/2022/11/03/Rust-1.65.0.html#stabilized-apis + println!("cargo:rustc-cfg=std_backtrace"); } } -fn compile_probe() -> Option<ExitStatus> { +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: @@ -76,13 +96,12 @@ fn compile_probe() -> Option<ExitStatus> { // https://github.com/rust-lang/rust/issues/114839 // // Let's just not use nightly features here. - return None; + return false; } - let rustc = env::var_os("RUSTC")?; - let out_dir = env::var_os("OUT_DIR")?; - let probefile = Path::new(&out_dir).join("probe.rs"); - fs::write(&probefile, PROBE).ok()?; + let rustc = cargo_env_var("RUSTC"); + let out_dir = cargo_env_var("OUT_DIR"); + let probefile = Path::new("build").join("probe.rs"); // Make sure to pick up Cargo rustc configuration. let mut cmd = if let Some(wrapper) = env::var_os("RUSTC_WRAPPER") { @@ -94,11 +113,15 @@ fn compile_probe() -> Option<ExitStatus> { Command::new(rustc) }; + if !rustc_bootstrap { + cmd.env_remove("RUSTC_BOOTSTRAP"); + } + cmd.stderr(Stdio::null()) .arg("--edition=2018") - .arg("--crate-name=anyhow_build") + .arg("--crate-name=anyhow") .arg("--crate-type=lib") - .arg("--emit=metadata") + .arg("--emit=dep-info,metadata") .arg("--out-dir") .arg(out_dir) .arg(probefile); @@ -116,11 +139,14 @@ fn compile_probe() -> Option<ExitStatus> { } } - cmd.status().ok() + match cmd.status() { + Ok(status) => status.success(), + Err(_) => false, + } } fn rustc_minor_version() -> Option<u32> { - let rustc = env::var_os("RUSTC")?; + let rustc = cargo_env_var("RUSTC"); let output = Command::new(rustc).arg("--version").output().ok()?; let version = str::from_utf8(&output.stdout).ok()?; let mut pieces = version.split('.'); @@ -129,3 +155,13 @@ fn rustc_minor_version() -> Option<u32> { } pieces.next()?.parse().ok() } + +fn cargo_env_var(key: &str) -> OsString { + env::var_os(key).unwrap_or_else(|| { + eprintln!( + "Environment variable ${} is not set during execution of build script", + key, + ); + process::exit(1); + }) +} |