Auto merge of #3413 - RalfJung:cargo-miri-misc, r=RalfJung

phase_rustdoc: add a heuristic to make us more certain that this is really rustdoc

Also add anyhow to test-cargo-miri; it has a custom build probe and is widely used so let's make sure the build script does not fail.

src/tools/miri/cargo-miri/src/main.rs

@@ -11,10 +11,18 @@ use std::{env, iter};
 
 use crate::phases::*;
 
+/// Returns `true` if our flags look like they may be for rustdoc, i.e., this is cargo calling us to
+/// be rustdoc. It's hard to be sure as cargo does not have a RUSTDOC_WRAPPER or an env var that
+/// would let us get a clear signal.
+fn looks_like_rustdoc() -> bool {
+    // The `--test-run-directory` flag only exists for rustdoc and cargo always passes it. Perfect!
+    env::args().any(|arg| arg == "--test-run-directory")
+}
+
 fn main() {
     // Rustc does not support non-UTF-8 arguments so we make no attempt either.
     // (We do support non-UTF-8 environment variables though.)
-    let mut args = std::env::args();
+    let mut args = env::args();
     // Skip binary name.
     args.next().unwrap();
 
@@ -91,10 +99,16 @@ fn main() {
             // (see https://github.com/rust-lang/cargo/issues/10886).
             phase_rustc(args, RustcPhase::Build)
         }
-        _ => {
-            // Everything else must be rustdoc. But we need to get `first` "back onto the iterator",
+        _ if looks_like_rustdoc() => {
+            // This is probably rustdoc. But we need to get `first` "back onto the iterator",
             // it is some part of the rustdoc invocation.
             phase_rustdoc(iter::once(first).chain(args));
         }
+        _ => {
+            show_error!(
+                "`cargo-miri` failed to recognize which phase of the build process this is, please report a bug.\nThe command-line arguments were: {:#?}",
+                Vec::from_iter(env::args()),
+            );
+        }
     }
 }

src/tools/miri/cargo-miri/src/phases.rs

@@ -620,7 +620,7 @@ pub fn phase_rustdoc(mut args: impl Iterator<Item = String>) {
 
     // The `--test-builder` and `--runtool` arguments are unstable rustdoc features,
     // which are disabled by default. We first need to enable them explicitly:
-    cmd.arg("-Z").arg("unstable-options");
+    cmd.arg("-Zunstable-options");
 
     // rustdoc needs to know the right sysroot.
     cmd.arg("--sysroot").arg(env::var_os("MIRI_SYSROOT").unwrap());

src/tools/miri/test-cargo-miri/Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "anyhow"
+version = "1.0.81"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0952808a6c2afd1aa8947271f3a60f1a6763c7b912d210184c5149b5cf147247"
+
 [[package]]
 name = "autocfg"
 version = "1.1.0"
@@ -24,6 +30,7 @@ checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
 name = "cargo-miri-test"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "autocfg",
  "byteorder 0.5.3",
  "byteorder 1.4.3",

src/tools/miri/test-cargo-miri/Cargo.toml

@@ -22,6 +22,9 @@ issue_rust_86261 = { path = "issue-rust-86261" }
 byteorder_2 = { package = "byteorder", version = "0.5" } # to test dev-dependencies behave as expected, with renaming
 # Not actually used, but exercises some unique code path (`--extern` .so file).
 serde_derive = "1.0.185"
+# Not actually used, but uses a custom build probe so let's make sure that works.
+# (Ideally we'd check if the probe was successful, but that's not easily possible.)
+anyhow = "1.0"
 
 [build-dependencies]
 autocfg = "1"