Auto merge of #64316 - alexcrichton:cleanup-shim, r=Mark-Simulacrum

Delete most of `src/bootstrap/bin/rustc.rs`

This commit is an attempt at deleting as much of the `rustc.rs` shim that we have in rustbuild as possible.  This shim predates `RUSTFLAGS` and is as old as rustbuild itself. While useful for quick hacks, it subverts Cargo's knowledge of `rustc`, makes it more difficult to build crates out of rustbuild, and is generally a hazard/code smell due to its architecture.

Additionally since the inception of this script we've added a number of features to Cargo such as profile overrides and `RUSTFLAGS`. This commit attempts to use these features of Cargo as much as possible to delete almost all of `src/bootstrap/bin/rustc.rs`. It's hoped that all new configuration for the Rust compiler can be codified in rustbuild rather than in this shim, allowing Cargo to have more knowledge about what's going on and making it a bit easier to reproduce builds outside of Cargo itself.

This was primarily motivated by some recent work on std-aware Cargo, and is also generally a cleanup of the script itself. This internally resulted in a number of refactorings of rustbuild itself, and the commits should be readable one-at-a-time instead of having to digest them all at once.

Author: bors

Cargo.lock

@@ -597,7 +597,6 @@ version = "0.28.0"
 dependencies = [
  "curl",
  "failure",
- "http",
  "percent-encoding 2.0.0",
  "serde",
  "serde_derive",

src/bootstrap/bin/rustc.rs

@@ -16,31 +16,14 @@
 //! never get replaced.
 
 use std::env;
-use std::ffi::OsString;
 use std::io;
 use std::path::PathBuf;
 use std::process::Command;
 use std::str::FromStr;
 use std::time::Instant;
 
 fn main() {
-    let mut args = env::args_os().skip(1).collect::<Vec<_>>();
-
-    // Append metadata suffix for internal crates. See the corresponding entry
-    // in bootstrap/lib.rs for details.
-    if let Ok(s) = env::var("RUSTC_METADATA_SUFFIX") {
-        for i in 1..args.len() {
-            // Dirty code for borrowing issues
-            let mut new = None;
-            if let Some(current_as_str) = args[i].to_str() {
-                if (&*args[i - 1] == "-C" && current_as_str.starts_with("metadata")) ||
-                    current_as_str.starts_with("-Cmetadata") {
-                    new = Some(format!("{}-{}", current_as_str, s));
-                }
-            }
-            if let Some(new) = new { args[i] = new.into(); }
-        }
-    }
+    let args = env::args_os().skip(1).collect::<Vec<_>>();
 
     // Detect whether or not we're a build script depending on whether --target
     // is passed (a bit janky...)
@@ -93,92 +76,19 @@ fn main() {
         }
     }
 
-    // Non-zero stages must all be treated uniformly to avoid problems when attempting to uplift
-    // compiler libraries and such from stage 1 to 2.
-    //
-    // FIXME: the fact that core here is excluded is due to core_arch from our stdarch submodule
-    // being broken on the beta compiler with bootstrap passed, so this is a temporary workaround
-    // (we've just snapped, so there are no cfg(bootstrap) related annotations in core).
-    if stage == "0" {
-        if crate_name != Some("core") {
-            cmd.arg("--cfg").arg("bootstrap");
-        } else {
-            // NOTE(eddyb) see FIXME above, except now we need annotations again in core.
-            cmd.arg("--cfg").arg("boostrap_stdarch_ignore_this");
-        }
-    }
-
     // Print backtrace in case of ICE
     if env::var("RUSTC_BACKTRACE_ON_ICE").is_ok() && env::var("RUST_BACKTRACE").is_err() {
         cmd.env("RUST_BACKTRACE", "1");
     }
 
-    cmd.env("RUSTC_BREAK_ON_ICE", "1");
-
-    if let Ok(debuginfo_level) = env::var("RUSTC_DEBUGINFO_LEVEL") {
-        cmd.arg(format!("-Cdebuginfo={}", debuginfo_level));
-    }
-
-    if env::var_os("RUSTC_EXTERNAL_TOOL").is_none() {
-        // When extending this list, add the new lints to the RUSTFLAGS of the
-        // build_bootstrap function of src/bootstrap/bootstrap.py as well as
-        // some code doesn't go through this `rustc` wrapper.
-        cmd.arg("-Wrust_2018_idioms");
-        cmd.arg("-Wunused_lifetimes");
-        if use_internal_lints(crate_name) {
-            cmd.arg("-Zunstable-options");
-            cmd.arg("-Wrustc::internal");
-        }
-        if env::var_os("RUSTC_DENY_WARNINGS").is_some() {
-            cmd.arg("-Dwarnings");
-        }
-    }
-
-    if let Some(target) = target {
+    if target.is_some() {
         // The stage0 compiler has a special sysroot distinct from what we
         // actually downloaded, so we just always pass the `--sysroot` option,
         // unless one is already set.
         if !args.iter().any(|arg| arg == "--sysroot") {
             cmd.arg("--sysroot").arg(&sysroot);
         }
 
-        cmd.arg("-Zexternal-macro-backtrace");
-
-        // Link crates to the proc macro crate for the target, but use a host proc macro crate
-        // to actually run the macros
-        if env::var_os("RUST_DUAL_PROC_MACROS").is_some() {
-            cmd.arg("-Zdual-proc-macros");
-        }
-
-        // When we build Rust dylibs they're all intended for intermediate
-        // usage, so make sure we pass the -Cprefer-dynamic flag instead of
-        // linking all deps statically into the dylib.
-        if env::var_os("RUSTC_NO_PREFER_DYNAMIC").is_none() {
-            cmd.arg("-Cprefer-dynamic");
-        }
-
-        // Help the libc crate compile by assisting it in finding various
-        // sysroot native libraries.
-        if let Some(s) = env::var_os("MUSL_ROOT") {
-            if target.contains("musl") {
-                let mut root = OsString::from("native=");
-                root.push(&s);
-                root.push("/lib");
-                cmd.arg("-L").arg(&root);
-            }
-        }
-        if let Some(s) = env::var_os("WASI_ROOT") {
-            let mut root = OsString::from("native=");
-            root.push(&s);
-            root.push("/lib/wasm32-wasi");
-            cmd.arg("-L").arg(&root);
-        }
-
-        // Override linker if necessary.
-        if let Ok(target_linker) = env::var("RUSTC_TARGET_LINKER") {
-            cmd.arg(format!("-Clinker={}", target_linker));
-        }
-
         // If we're compiling specifically the `panic_abort` crate then we pass
         // the `-C panic=abort` option. Note that we do not do this for any
         // other crate intentionally as this is the only crate for now that we
@@ -205,82 +115,18 @@ fn main() {
 
         // The compiler builtins are pretty sensitive to symbols referenced in
         // libcore and such, so we never compile them with debug assertions.
+        //
+        // FIXME(rust-lang/cargo#7253) we should be doing this in `builder.rs`
+        // with env vars instead of doing it here in this script.
         if crate_name == Some("compiler_builtins") {
             cmd.arg("-C").arg("debug-assertions=no");
         } else {
             cmd.arg("-C").arg(format!("debug-assertions={}", debug_assertions));
         }
-
-        if let Ok(s) = env::var("RUSTC_CODEGEN_UNITS") {
-            cmd.arg("-C").arg(format!("codegen-units={}", s));
-        }
-
-        // Emit save-analysis info.
-        if env::var("RUSTC_SAVE_ANALYSIS") == Ok("api".to_string()) {
-            cmd.arg("-Zsave-analysis");
-            cmd.env("RUST_SAVE_ANALYSIS_CONFIG",
-                    "{\"output_file\": null,\"full_docs\": false,\
-                     \"pub_only\": true,\"reachable_only\": false,\
-                     \"distro_crate\": true,\"signatures\": false,\"borrow_data\": false}");
-        }
-
-        // Dealing with rpath here is a little special, so let's go into some
-        // detail. First off, `-rpath` is a linker option on Unix platforms
-        // which adds to the runtime dynamic loader path when looking for
-        // dynamic libraries. We use this by default on Unix platforms to ensure
-        // that our nightlies behave the same on Windows, that is they work out
-        // of the box. This can be disabled, of course, but basically that's why
-        // we're gated on RUSTC_RPATH here.
-        //
-        // Ok, so the astute might be wondering "why isn't `-C rpath` used
-        // here?" and that is indeed a good question to task. This codegen
-        // option is the compiler's current interface to generating an rpath.
-        // Unfortunately it doesn't quite suffice for us. The flag currently
-        // takes no value as an argument, so the compiler calculates what it
-        // should pass to the linker as `-rpath`. This unfortunately is based on
-        // the **compile time** directory structure which when building with
-        // Cargo will be very different than the runtime directory structure.
-        //
-        // All that's a really long winded way of saying that if we use
-        // `-Crpath` then the executables generated have the wrong rpath of
-        // something like `$ORIGIN/deps` when in fact the way we distribute
-        // rustc requires the rpath to be `$ORIGIN/../lib`.
-        //
-        // So, all in all, to set up the correct rpath we pass the linker
-        // argument manually via `-C link-args=-Wl,-rpath,...`. Plus isn't it
-        // fun to pass a flag to a tool to pass a flag to pass a flag to a tool
-        // to change a flag in a binary?
-        if env::var("RUSTC_RPATH") == Ok("true".to_string()) {
-            let rpath = if target.contains("apple") {
-
-                // Note that we need to take one extra step on macOS to also pass
-                // `-Wl,-instal_name,@rpath/...` to get things to work right. To
-                // do that we pass a weird flag to the compiler to get it to do
-                // so. Note that this is definitely a hack, and we should likely
-                // flesh out rpath support more fully in the future.
-                cmd.arg("-Z").arg("osx-rpath-install-name");
-                Some("-Wl,-rpath,@loader_path/../lib")
-            } else if !target.contains("windows") &&
-                      !target.contains("wasm32") &&
-                      !target.contains("fuchsia") {
-                Some("-Wl,-rpath,$ORIGIN/../lib")
-            } else {
-                None
-            };
-            if let Some(rpath) = rpath {
-                cmd.arg("-C").arg(format!("link-args={}", rpath));
-            }
-        }
-
-        if let Ok(s) = env::var("RUSTC_CRT_STATIC") {
-            if s == "true" {
-                cmd.arg("-C").arg("target-feature=+crt-static");
-            }
-            if s == "false" {
-                cmd.arg("-C").arg("target-feature=-crt-static");
-            }
-        }
     } else {
+        // FIXME(rust-lang/cargo#5754) we shouldn't be using special env vars
+        // here, but rather Cargo should know what flags to pass rustc itself.
+
         // Override linker if necessary.
         if let Ok(host_linker) = env::var("RUSTC_HOST_LINKER") {
             cmd.arg(format!("-Clinker={}", host_linker));
@@ -308,10 +154,6 @@ fn main() {
         cmd.arg("-Z").arg("force-unstable-if-unmarked");
     }
 
-    if env::var_os("RUSTC_PARALLEL_COMPILER").is_some() {
-        cmd.arg("--cfg").arg("parallel_compiler");
-    }
-
     if verbose > 1 {
         eprintln!(
             "rustc command: {:?}={:?} {:?}",
@@ -362,14 +204,6 @@ fn main() {
     std::process::exit(code);
 }
 
-// Rustc crates for which internal lints are in effect.
-fn use_internal_lints(crate_name: Option<&str>) -> bool {
-    crate_name.map_or(false, |crate_name| {
-        crate_name.starts_with("rustc") || crate_name.starts_with("syntax") ||
-        ["arena", "fmt_macros"].contains(&crate_name)
-    })
-}
-
 #[cfg(unix)]
 fn exec_cmd(cmd: &mut Command) -> io::Result<i32> {
     use std::os::unix::process::CommandExt;