Add test for -Znew-llvm-pass-manager -Clto=thin -Zsanitizer=...

Additionally verify that the current implementation of LLVM version
check (which uses lexicographic ordering) is good enough to exclude
versions before LLVM 9, where the new LLVM pass manager is unsupported.

src/test/ui/sanitize/new-llvm-pass-manager-thin-lto.rs

@@ -0,0 +1,27 @@
+// Regression test for sanitizer function instrumentation passes not
+// being run when compiling with new LLVM pass manager and ThinLTO.
+// Note: The issue occured only on non-zero opt-level.
+//
+// min-llvm-version 9.0
+// needs-sanitizer-support
+// only-x86_64
+//
+// no-prefer-dynamic
+// revisions: opt0 opt1
+// compile-flags: -Znew-llvm-pass-manager=yes -Zsanitizer=address -Clto=thin
+//[opt0]compile-flags: -Copt-level=0
+//[opt1]compile-flags: -Copt-level=1
+// run-fail
+// error-pattern: ERROR: AddressSanitizer: stack-use-after-scope
+
+static mut P: *mut usize = std::ptr::null_mut();
+
+fn main() {
+    unsafe {
+        {
+            let mut x = 0;
+            P = &mut x;
+        }
+        std::ptr::write_volatile(P, 123);
+    }
+}

src/tools/compiletest/src/header/tests.rs

@@ -109,6 +109,24 @@ fn no_system_llvm() {
     assert!(parse_rs(&config, "// no-system-llvm").ignore);
 }
 
+#[test]
+fn llvm_version() {
+    let mut config = config();
+
+    config.llvm_version = Some("8.1.2-rust".to_owned());
+    assert!(parse_rs(&config, "// min-llvm-version 9.0").ignore);
+
+    config.llvm_version = Some("9.0.1-rust-1.43.0-dev".to_owned());
+    assert!(parse_rs(&config, "// min-llvm-version 9.2").ignore);
+
+    config.llvm_version = Some("9.3.1-rust-1.43.0-dev".to_owned());
+    assert!(!parse_rs(&config, "// min-llvm-version 9.2").ignore);
+
+    // FIXME.
+    // config.llvm_version = Some("10.0.0-rust".to_owned());
+    // assert!(!parse_rs(&config, "// min-llvm-version 9.0").ignore);
+}
+
 #[test]
 fn ignore_target() {
     let mut config = config();