Auto merge of rust-lang#131077 - lqd:debug-assertions-alt, r=<try>

Enable debug assertions on alt builds

Alt builds already have llvm assertions enabled, and this PR adds rustc's debug assertions.

We've discussed that this would be useful a few times in the past, most recently in [this zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/cargo.20bisect-rustc'ing.20a.20debug.20assertions-only.20ICE), for example to bisect the source PR of an unexpected tripped debug assert, which is not that rare of an occurrence.

[In another thread](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Alt.20builds.20with.20debug.20assertions) we discussed how it would help with Matthias' fuzzing workflow, and some of Ben's work.

I don't _believe_ this needs an MCP, but am not sure.

To my knowledge there are 2 alt builds (x64 linux, x64 msvc) and this enables it for both, though we could limit to x64 linux if we wanted to.

try-job: dist-x86_64-msvc-alt
try-job: dist-x86-64-linux-alt

Author: bors

src/ci/run.sh

@@ -134,6 +134,11 @@ if [ "$DEPLOY$DEPLOY_ALT" = "1" ]; then
 
   CODEGEN_BACKENDS="${CODEGEN_BACKENDS:-llvm}"
   RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-backends=$CODEGEN_BACKENDS"
+
+  # Unless explicitly disabled, we want rustc debug assertions on the -alt builds
+  if [ "$DEPLOY_ALT" != "" ] && [ "$NO_DEBUG_ASSERTIONS" = "" ]; then
+    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --enable-debug-assertions"
+  fi
 else
   # We almost always want debug assertions enabled, but sometimes this takes too
   # long for too little benefit, so we just turn them off.

src/tools/opt-dist/src/environment.rs

@@ -25,6 +25,27 @@ pub struct Environment {
     prebuilt_rustc_perf: Option<Utf8PathBuf>,
     use_bolt: bool,
     shared_llvm: bool,
+    /// Additional configuration that bootstrap needs to know only when running tests.
+    #[builder(default)]
+    test_config: TestConfig,
+}
+
+/// Builds have optional components, and their presence/absence can enable/disable a subset of
+/// tests. When testing the optimized artifacts, bootstrap needs to know about these enabled
+/// components to run the expected subset. This structure holds the known components where this
+/// matters: currently only whether the build to test is using debug assertions.
+///
+/// FIXME: ultimately, this is a temporary band-aid, and opt-dist should be more transparent to the
+/// CI config and bootstrap optional components: bootstrap has default values, combinations of flags
+/// that cascade into others, etc logic that we'd have to duplicate here otherwise. It's more
+/// sensible for opt-dist to never know about the config apart from the minimal set of paths
+/// required to configure stage0 tests.
+#[derive(Builder, Default, Clone, Debug)]
+pub struct TestConfig {
+    /// Whether the build under test is explicitly using `--enable-debug-assertions`.
+    /// Note that this flag can be implied from others, like `rust.debug`, and we do not handle any
+    /// of these subtleties and defaults here, as per the FIXME above.
+    pub rust_debug_assertions: bool,
 }
 
 impl Environment {
@@ -101,6 +122,21 @@ impl Environment {
     pub fn benchmark_cargo_config(&self) -> &[String] {
         &self.benchmark_cargo_config
     }
+
+    pub fn test_config(&self) -> &TestConfig {
+        &self.test_config
+    }
+}
+
+impl TestConfig {
+    /// Returns the test config matching the given `RUST_CONFIGURE_ARGS` for the known optional
+    /// components for tests. This is obviously extremely fragile and we'd rather opt-dist not
+    /// handle any optional components.
+    pub fn from_configure_args(configure_args: &str) -> TestConfig {
+        let enable_debug_assertions =
+            configure_args.split(" ").find(|part| *part == "--enable-debug-assertions").is_some();
+        TestConfig { rust_debug_assertions: enable_debug_assertions }
+    }
 }
 
 /// What is the extension of binary executables on this platform?

src/tools/opt-dist/src/main.rs

@@ -1,6 +1,7 @@
 use anyhow::Context;
 use camino::{Utf8Path, Utf8PathBuf};
 use clap::Parser;
+use environment::TestConfig;
 use log::LevelFilter;
 use utils::io;
 
@@ -148,6 +149,11 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
 
             let is_aarch64 = target_triple.starts_with("aarch64");
 
+            // Parse the optional build components that impact the test environment.
+            let rust_configure_args = std::env::var("RUST_CONFIGURE_ARGS")
+                .expect("RUST_CONFIGURE_ARGS environment variable missing");
+            let test_config = TestConfig::from_configure_args(&rust_configure_args);
+
             let checkout_dir = Utf8PathBuf::from("/checkout");
             let env = EnvironmentBuilder::default()
                 .host_tuple(target_triple)
@@ -160,6 +166,7 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
                 // FIXME: Enable bolt for aarch64 once it's fixed upstream. Broken as of December 2024.
                 .use_bolt(!is_aarch64)
                 .skipped_tests(vec![])
+                .test_config(test_config)
                 .build()?;
 
             (env, shared.build_args)
@@ -168,6 +175,11 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
             let target_triple =
                 std::env::var("PGO_HOST").expect("PGO_HOST environment variable missing");
 
+            // Parse the optional build components that impact the test environment.
+            let rust_configure_args = std::env::var("RUST_CONFIGURE_ARGS")
+                .expect("RUST_CONFIGURE_ARGS environment variable missing");
+            let test_config = TestConfig::from_configure_args(&rust_configure_args);
+
             let checkout_dir: Utf8PathBuf = std::env::current_dir()?.try_into()?;
             let env = EnvironmentBuilder::default()
                 .host_tuple(target_triple)
@@ -179,6 +191,7 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
                 .shared_llvm(false)
                 .use_bolt(false)
                 .skipped_tests(vec![])
+                .test_config(test_config)
                 .build()?;
 
             (env, shared.build_args)

src/tools/opt-dist/src/tests.rs

@@ -72,6 +72,7 @@ change-id = 115898
 [rust]
 channel = "{channel}"
 verbose-tests = true
+debug-assertions = {debug_assertions}
 
 [build]
 rustc = "{rustc}"
@@ -83,7 +84,8 @@ llvm-config = "{llvm_config}"
 "#,
         rustc = rustc_path.to_string().replace('\\', "/"),
         cargo = cargo_path.to_string().replace('\\', "/"),
-        llvm_config = llvm_config.to_string().replace('\\', "/")
+        llvm_config = llvm_config.to_string().replace('\\', "/"),
+        debug_assertions = env.test_config().rust_debug_assertions,
     );
     log::info!("Using following `bootstrap.toml` for running tests:\n{config_content}");