From cdda9008a375db062c3a69125c263ccf61323aa7 Mon Sep 17 00:00:00 2001
From: heisen-li <liziqiang5@huawei.com>
Date: Fri, 8 Mar 2024 20:33:22 +0800
Subject: [PATCH 1/2] fix: show build script didnt rerun when target rustflags
 changed

---
 tests/testsuite/build_script.rs | 54 +++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/tests/testsuite/build_script.rs b/tests/testsuite/build_script.rs
index a60c59b0b25..8da34c44075 100644
--- a/tests/testsuite/build_script.rs
+++ b/tests/testsuite/build_script.rs
@@ -5527,3 +5527,57 @@ fn test_old_syntax_with_old_msrv() {
     p.cargo("build -v").run();
     p.cargo("run -v").with_stdout("foo\n").run();
 }
+
+#[cargo_test]
+fn build_script_rerun_when_target_rustflags_change() {
+    let target = rustc_host();
+    let p = project()
+        .file(
+            "src/main.rs",
+            r#"
+            fn main() {
+                #[cfg(enable)]
+                println!("hello");
+            }
+            "#,
+        )
+        .file(
+            "build.rs",
+            r#"
+            use std::env;
+
+            fn main() {
+                if let Ok(rustflags) = env::var("CARGO_ENCODED_RUSTFLAGS") {
+                    if !rustflags.is_empty() {
+                        println!("cargo::rustc-cfg=enable")
+                    }
+                }
+            }
+            "#,
+        )
+        .build();
+
+    p.cargo("run --target")
+        .arg(&target)
+        .with_stderr(
+            "\
+[COMPILING] foo v0.0.1 ([..])
+[FINISHED] [..]
+[RUNNING] [..]
+",
+        )
+        .run();
+
+    p.cargo("run --target")
+        .arg(&target)
+        .env("RUSTFLAGS", "-C opt-level=3")
+        .with_stderr(
+            "\
+[COMPILING] foo v0.0.1 ([..])
+[FINISHED] [..]
+[RUNNING] [..]
+",
+        )
+        .with_stdout("")
+        .run();
+}

From db7afeba4e415626d78eb3f2e6005fa303f82f59 Mon Sep 17 00:00:00 2001
From: heisen-li <liziqiang5@huawei.com>
Date: Sun, 7 Apr 2024 19:58:23 +0800
Subject: [PATCH 2/2] fix: rerun build script when target rustflags changed

fixes #13003
---
 src/cargo/core/compiler/fingerprint/mod.rs | 3 +++
 tests/testsuite/build_script.rs            | 5 ++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/cargo/core/compiler/fingerprint/mod.rs b/src/cargo/core/compiler/fingerprint/mod.rs
index 4fdbed220c1..f3389b49f58 100644
--- a/src/cargo/core/compiler/fingerprint/mod.rs
+++ b/src/cargo/core/compiler/fingerprint/mod.rs
@@ -1526,11 +1526,14 @@ See https://doc.rust-lang.org/cargo/reference/build-scripts.html#rerun-if-change
             .collect::<CargoResult<Vec<_>>>()?
     };
 
+    let rustflags = build_runner.bcx.rustflags_args(unit).to_vec();
+
     Ok(Fingerprint {
         local: Mutex::new(local),
         rustc: util::hash_u64(&build_runner.bcx.rustc().verbose_version),
         deps,
         outputs: if overridden { Vec::new() } else { vec![output] },
+        rustflags,
 
         // Most of the other info is blank here as we don't really include it
         // in the execution of the build script, but... this may be a latent
diff --git a/tests/testsuite/build_script.rs b/tests/testsuite/build_script.rs
index 8da34c44075..2f75826bd59 100644
--- a/tests/testsuite/build_script.rs
+++ b/tests/testsuite/build_script.rs
@@ -5578,6 +5578,9 @@ fn build_script_rerun_when_target_rustflags_change() {
 [RUNNING] [..]
 ",
         )
-        .with_stdout("")
+        .with_stdout(
+            "\
+hello",
+        )
         .run();
 }