redo ./run-test.sh based on MIRI_REPLACE_LIBRS_IF_NOT_TEST

Author: RalfJung

Cargo.toml

@@ -1,12 +1,22 @@
+# We set up our own workspace that contains the library crates.
+# `./run-test.sh` makes the `library` folder a symlink to the right place.
+# (Somehow, directly building things from `rustlib/src` does not work...)
 [workspace]
 members = [
-  "core_miri_test",
-  "alloc_miri_test",
-  "std_miri_test",
+  "library/std",
+  "library/sysroot",
 ]
 
 exclude = [
   # stdarch has its own Cargo workspace
   "library/stdarch",
-  "rust-src-patched/library/stdarch",
+  # this is just a staging ground for CI
+  "rust-src-patched",
 ]
+
+[patch.crates-io]
+# See comments in `library/rustc-std-workspace-core/README.md` for what's going on
+# here
+rustc-std-workspace-core = { path = 'library/rustc-std-workspace-core' }
+rustc-std-workspace-alloc = { path = 'library/rustc-std-workspace-alloc' }
+rustc-std-workspace-std = { path = 'library/rustc-std-workspace-std' }

alloc_miri_test/Cargo.toml

@@ -85,9 +85,10 @@ std)
     echo "::endgroup::"
     ;;
 simd)
-    cd $MIRI_LIB_SRC/portable-simd
+    export CARGO_TARGET_DIR=$(pwd)/target
     export RUSTFLAGS="-Ainternal_features ${RUSTFLAGS:-}"
     export RUSTDOCFLAGS="-Ainternal_features ${RUSTDOCFLAGS:-}"
+    cd $MIRI_LIB_SRC/portable-simd
 
     echo "::group::Testing portable-simd"
     MIRIFLAGS="$DEFAULTFLAGS" \

ci-test.sh

@@ -6,7 +6,7 @@ set -euo pipefail
 ## Usage:
 ##   ./run-test.sh TARGET
 ## Environment variables:
-##   MIRI_LIB_SRC: The path to the Rust library directory (`library`).
+##   MIRI_LIB_SRC: The path to the Rust `library` directory (optional).
 ##   RUSTFLAGS: rustc flags (optional)
 ##   MIRIFLAGS: Miri flags (optional)
 
@@ -40,8 +40,11 @@ export STDARCH_TEST_EVERYTHING=1
 # Needed to pass the STDARCH_TEST_EVERYTHING environment variable
 export MIRIFLAGS="${MIRIFLAGS:-} -Zmiri-disable-isolation"
 
-cd $MIRI_LIB_SRC/stdarch
+# Set library source dir
+export MIRI_LIB_SRC=${MIRI_LIB_SRC:-$(rustc --print sysroot)/lib/rustlib/src/rust/library}
+
+export CARGO_TARGET_DIR=$(pwd)/target
 cargo miri test \
+    --manifest-path=$MIRI_LIB_SRC/stdarch/crates/core_arch/Cargo.toml \
     --target "$TARGET" \
-    --manifest-path=crates/core_arch/Cargo.toml \
     -- "${TEST_ARGS[@]}"

core_miri_test/Cargo.toml

@@ -35,6 +35,10 @@ ln -s "$MIRI_LIB_SRC" library
 # use the rust-src lockfile
 cp "$MIRI_LIB_SRC/../Cargo.lock" Cargo.lock
 
+# This ensures that the "core" crate being built as part of `cargo miri test`
+# is just a re-export of the sysroot crate, so we don't get duplicate lang items.
+export MIRI_REPLACE_LIBRS_IF_NOT_TEST=1
+
 # run test
-cd ./${CRATE}_miri_test
-cargo miri test "$@"
+export CARGO_TARGET_DIR=$(pwd)/target
+cargo miri test --manifest-path "library/$CRATE/Cargo.toml" "$@"

fake/README.md

@@ -0,0 +1,35 @@
+diff --git a/library/alloc/benches/lib.rs b/library/alloc/benches/lib.rs
+index 638f343fb24..0561f49c967 100644
+--- a/library/alloc/benches/lib.rs
++++ b/library/alloc/benches/lib.rs
+@@ -1,6 +1,8 @@
+ // Disabling on android for the time being
+ // See https://github.com/rust-lang/rust/issues/73535#event-3477699747
+ #![cfg(not(target_os = "android"))]
++// Disabling in Miri as these would take too long.
++#![cfg(not(miri))]
+ #![feature(btree_extract_if)]
+ #![feature(iter_next_chunk)]
+ #![feature(repr_simd)]
+diff --git a/library/core/benches/lib.rs b/library/core/benches/lib.rs
+index 4d14b930e41..32d15c386cb 100644
+--- a/library/core/benches/lib.rs
++++ b/library/core/benches/lib.rs
+@@ -1,5 +1,7 @@
+ // wasm32 does not support benches (no time).
+ #![cfg(not(target_arch = "wasm32"))]
++// Disabling in Miri as these would take too long.
++#![cfg(not(miri))]
+ #![feature(flt2dec)]
+ #![feature(test)]
+ #![feature(trusted_random_access)]
+diff --git a/library/std/benches/lib.rs b/library/std/benches/lib.rs
+index 4d1cf7fab7b..1b21c230a0b 100644
+--- a/library/std/benches/lib.rs
++++ b/library/std/benches/lib.rs
+@@ -1,3 +1,5 @@
++// Disabling in Miri as these would take too long.
++#![cfg(not(miri))]
+ #![feature(test)]
+ 
+ extern crate test;

fake/alloc/Cargo.toml

@@ -1 +1 @@
-nightly-2024-04-01
+nightly-2024-04-06