Rollup merge of #123975 - lqd:rust-lld-tests, r=jieyouxu

Port the 2 `rust-lld` run-make tests to `rmake`

In preparation for finalizing most of the `rust-lld` work, this PR ports the following tests to `rmake`:
- `tests/run-make/rust-lld`
- `tests/run-make/rust-lld-custom-target`

As they use `$(CGREP) -e` I added `regex` as an exported dependency to the `run_make_support` library.

Unfortunately, the most recent versions depend on `memchr` 2.6.0 but it's currently pinned at 2.5.0 in the workspace, and therefore had to settle for the older `regex-1.8.0`.

r? `@jieyouxu`

Author: GuillaumeGomez

Cargo.lock

@@ -3342,6 +3342,7 @@ name = "run_make_support"
 version = "0.0.0"
 dependencies = [
  "object 0.34.0",
+ "regex",
  "wasmparser",
 ]
 

src/tools/compiletest/src/header.rs

@@ -842,6 +842,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "needs-profiler-support",
     "needs-relocation-model-pic",
     "needs-run-enabled",
+    "needs-rust-lld",
     "needs-rust-lldb",
     "needs-sanitizer-address",
     "needs-sanitizer-cfi",

src/tools/run-make-support/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 [dependencies]
 object = "0.34.0"
 wasmparser = "0.118.2"
+regex = "1.8" # 1.8 to avoid memchr 2.6.0, as 2.5.0 is pinned in the workspace

src/tools/run-make-support/src/lib.rs

@@ -13,6 +13,7 @@ use std::path::{Path, PathBuf};
 use std::process::{Command, Output};
 
 pub use object;
+pub use regex;
 pub use wasmparser;
 
 pub use cc::{cc, extra_c_flags, extra_cxx_flags, Cc};

src/tools/run-make-support/src/rustc.rs

@@ -128,9 +128,8 @@ impl Rustc {
         self
     }
 
-    /// Specify target triple.
+    /// Specify the target triple, or a path to a custom target json spec file.
     pub fn target(&mut self, target: &str) -> &mut Self {
-        assert!(!target.contains(char::is_whitespace), "target triple cannot contain spaces");
         self.cmd.arg(format!("--target={target}"));
         self
     }
@@ -149,6 +148,12 @@ impl Rustc {
         self
     }
 
+    /// Add an extra argument to the linker invocation, via `-Clink-arg`.
+    pub fn link_arg(&mut self, link_arg: &str) -> &mut Self {
+        self.cmd.arg(format!("-Clink-arg={link_arg}"));
+        self
+    }
+
     #[track_caller]
     pub fn run_fail_assert_exit_code(&mut self, code: i32) -> Output {
         let caller_location = std::panic::Location::caller();

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -249,8 +249,6 @@ run-make/rlib-format-packed-bundled-libs-2/Makefile
 run-make/rlib-format-packed-bundled-libs-3/Makefile
 run-make/rlib-format-packed-bundled-libs/Makefile
 run-make/rmeta-preferred/Makefile
-run-make/rust-lld-custom-target/Makefile
-run-make/rust-lld/Makefile
 run-make/rustc-macro-dep-files/Makefile
 run-make/rustdoc-determinism/Makefile
 run-make/rustdoc-error-lines/Makefile

tests/run-make/rust-lld-custom-target/Makefile

@@ -0,0 +1,51 @@
+// Test linking using `cc` with `rust-lld`, using a custom target with features described in MCP 510
+// see https://github.com/rust-lang/compiler-team/issues/510 for more info:
+//
+// Starting from the `x86_64-unknown-linux-gnu` target spec, we add the following options:
+// - a linker-flavor using lld via a C compiler
+// - the self-contained linker component is enabled
+
+//@ needs-rust-lld
+//@ only-x86_64-unknown-linux-gnu
+
+extern crate run_make_support;
+
+use run_make_support::regex::Regex;
+use run_make_support::rustc;
+use std::process::Output;
+
+fn main() {
+    // Compile to a custom target spec with rust-lld enabled by default. We'll check that by asking
+    // the linker to display its version number with a link-arg.
+    let output = rustc()
+        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
+        .crate_type("cdylib")
+        .target("custom-target.json")
+        .link_arg("-Wl,-v")
+        .input("lib.rs")
+        .run();
+    assert!(
+        find_lld_version_in_logs(output),
+        "the LLD version string should be present in the output logs"
+    );
+
+    // But it can also be disabled via linker features.
+    let output = rustc()
+        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
+        .crate_type("cdylib")
+        .target("custom-target.json")
+        .arg("-Zlinker-features=-lld")
+        .link_arg("-Wl,-v")
+        .input("lib.rs")
+        .run();
+    assert!(
+        !find_lld_version_in_logs(output),
+        "the LLD version string should not be present in the output logs"
+    );
+}
+
+fn find_lld_version_in_logs(output: Output) -> bool {
+    let lld_version_re = Regex::new(r"^LLD [0-9]+\.[0-9]+\.[0-9]+").unwrap();
+    let stderr = std::str::from_utf8(&output.stderr).unwrap();
+    stderr.lines().any(|line| lld_version_re.is_match(line))
+}

tests/run-make/rust-lld-custom-target/rmake.rs

@@ -0,0 +1,64 @@
+// Test linking using `cc` with `rust-lld`, using the unstable CLI described in MCP 510
+// see https://github.com/rust-lang/compiler-team/issues/510 for more info
+
+//@ needs-rust-lld
+//@ ignore-msvc
+//@ ignore-s390x lld does not yet support s390x as target
+
+extern crate run_make_support;
+
+use run_make_support::regex::Regex;
+use run_make_support::rustc;
+use std::process::Output;
+
+fn main() {
+    // Opt-in to lld and the self-contained linker, to link with rust-lld. We'll check that by
+    // asking the linker to display its version number with a link-arg.
+    let output = rustc()
+        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
+        .arg("-Zlinker-features=+lld")
+        .arg("-Clink-self-contained=+linker")
+        .arg("-Zunstable-options")
+        .link_arg("-Wl,-v")
+        .input("main.rs")
+        .run();
+    assert!(
+        find_lld_version_in_logs(output),
+        "the LLD version string should be present in the output logs"
+    );
+
+    // It should not be used when we explictly opt-out of lld.
+    let output = rustc()
+        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
+        .link_arg("-Wl,-v")
+        .arg("-Zlinker-features=-lld")
+        .input("main.rs")
+        .run();
+    assert!(
+        !find_lld_version_in_logs(output),
+        "the LLD version string should not be present in the output logs"
+    );
+
+    // While we're here, also check that the last linker feature flag "wins" when passed multiple
+    // times to rustc.
+    let output = rustc()
+        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
+        .link_arg("-Wl,-v")
+        .arg("-Clink-self-contained=+linker")
+        .arg("-Zunstable-options")
+        .arg("-Zlinker-features=-lld")
+        .arg("-Zlinker-features=+lld")
+        .arg("-Zlinker-features=-lld,+lld")
+        .input("main.rs")
+        .run();
+    assert!(
+        find_lld_version_in_logs(output),
+        "the LLD version string should be present in the output logs"
+    );
+}
+
+fn find_lld_version_in_logs(output: Output) -> bool {
+    let lld_version_re = Regex::new(r"^LLD [0-9]+\.[0-9]+\.[0-9]+").unwrap();
+    let stderr = std::str::from_utf8(&output.stderr).unwrap();
+    stderr.lines().any(|line| lld_version_re.is_match(line))
+}