Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 35 insertions, 24 deletions

diff --git a/src/bootstrap/bin/llvm-config-wrapper.rs b/src/bootstrap/bin/llvm-config-wrapper.rs
deleted file mode 100644
index 89984bb55..000000000
--- a/src/bootstrap/bin/llvm-config-wrapper.rs
+++ /dev/null
@@ -1,24 +0,0 @@
-// The sheer existence of this file is an awful hack. See the comments in
-// `src/bootstrap/native.rs` for why this is needed when compiling LLD.
-
-use std::env;
-use std::io::{self, Write};
-use std::process::{self, Command, Stdio};
-
-fn main() {
-    let real_llvm_config = env::var_os("LLVM_CONFIG_REAL").unwrap();
-    let mut cmd = Command::new(real_llvm_config);
-    cmd.args(env::args().skip(1)).stderr(Stdio::piped());
-    let output = cmd.output().expect("failed to spawn llvm-config");
-    let mut stdout = String::from_utf8_lossy(&output.stdout);
-
-    if let Ok(to_replace) = env::var("LLVM_CONFIG_SHIM_REPLACE") {
-        if let Ok(replace_with) = env::var("LLVM_CONFIG_SHIM_REPLACE_WITH") {
-            stdout = stdout.replace(&to_replace, &replace_with).into();
-        }
-    }
-
-    print!("{}", stdout.replace("\\", "/"));
-    io::stdout().flush().unwrap();
-    process::exit(output.status.code().unwrap_or(1));
-}
diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index 1d5260228..9611c866d 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -154,6 +154,41 @@ fn main() {
         cmd.arg("-Z").arg("force-unstable-if-unmarked");
     }
 
+    // allow-features is handled from within this rustc wrapper because of
+    // issues with build scripts. Some packages use build scripts to
+    // dynamically detect if certain nightly features are available.
+    // There are different ways this causes problems:
+    //
+    // * rustix runs `rustc` on a small test program to see if the feature is
+    //   available (and sets a `cfg` if it is). It does not honor
+    //   CARGO_ENCODED_RUSTFLAGS.
+    // * proc-macro2 detects if `rustc -vV` says "nighty" or "dev" and enables
+    //   nightly features. It will scan CARGO_ENCODED_RUSTFLAGS for
+    //   -Zallow-features. Unfortunately CARGO_ENCODED_RUSTFLAGS is not set
+    //   for build-dependencies when --target is used.
+    //
+    // The issues above means we can't just use RUSTFLAGS, and we can't use
+    // `cargo -Zallow-features=…`. Passing it through here ensures that it
+    // always gets set. Unfortunately that also means we need to enable more
+    // features than we really want (like those for proc-macro2), but there
+    // isn't much of a way around it.
+    //
+    // I think it is unfortunate that build scripts are doing this at all,
+    // since changes to nightly features can cause crates to break even if the
+    // user didn't want or care about the use of the nightly features. I think
+    // nightly features should be opt-in only. Unfortunately the dynamic
+    // checks are now too wide spread that we just need to deal with it.
+    //
+    // If you want to try to remove this, I suggest working with the crate
+    // authors to remove the dynamic checking. Another option is to pursue
+    // https://github.com/rust-lang/cargo/issues/11244 and
+    // https://github.com/rust-lang/cargo/issues/4423, which will likely be
+    // very difficult, but could help expose -Zallow-features into build
+    // scripts so they could try to honor them.
+    if let Ok(allow_features) = env::var("RUSTC_ALLOW_FEATURES") {
+        cmd.arg(format!("-Zallow-features={allow_features}"));
+    }
+
     if let Ok(flags) = env::var("MAGIC_EXTRA_RUSTFLAGS") {
         for flag in flags.split(' ') {
             cmd.arg(flag);