From bfd148b783febe248f4d601c8d9d542348345bf0 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Mon, 18 Jul 2022 17:47:32 -0400
Subject: [PATCH] use env vars, not Cargo.toml, to configure out dev profile

---
 Cargo.toml | 5 +++--
 miri       | 6 +++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index a2a880f8e30..208b3a76443 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -56,5 +56,6 @@ harness = false
 default = ["stack-cache"]
 stack-cache = []
 
-[profile.dev]
-opt-level = 2 # because it's too slow otherwise
+# Be aware that this file is inside a workspace when used via the
+# submodule in the rustc repo. That means there are many cargo features
+# we cannot use, such as profiles.
diff --git a/miri b/miri
index bb2fc5b1231..04d441b6078 100755
--- a/miri
+++ b/miri
@@ -96,10 +96,14 @@ fi
 
 # Prepare flags for cargo and rustc.
 CARGO="cargo +$TOOLCHAIN"
+# Share target dir between `miri` and `cargo-miri`.
 if [ -z "$CARGO_TARGET_DIR" ]; then
-    # Share target dir between `miri` and `cargo-miri`.
     export CARGO_TARGET_DIR="$MIRIDIR/target"
 fi
+# We configure dev builds to not be unusably slow.
+if [ -z "$CARGO_PROFILE_DEV_OPT_LEVEL" ]; then
+    export CARGO_PROFILE_DEV_OPT_LEVEL=2
+fi
 # We set the rpath so that Miri finds the private rustc libraries it needs.
 export RUSTFLAGS="-C link-args=-Wl,-rpath,$LIBDIR $RUSTFLAGS"