ctest: add foreign static test by mbyx · Pull Request #4601 · rust-lang/libc

mbyx · 2025-07-30T09:38:11Z

Description

Adds support for testing extern statics.

Also adds support for parsing any dimensional array in make_cdecl, and makes it easier to extract ffi safe types from Option.

Sources

Checklist

Relevant tests in libc-test/semver have been updated
No placeholder or unstable values like *LAST or *MAX are
included (see #3131)
Tested locally (cd libc-test && cargo test --target mytarget);
especially relevant for platforms that may not be checked in CI

ctest-next/templates/test.rs

tgross35 · 2025-08-09T12:54:05Z

ctest-next/templates/test.c

+{%- if static_.rust_ty.contains("extern") +%}
+typedef {{ static_.return_type }};
+ctest_static_ty__{{ static_.id }} ctest_static__{{ static_.id }}(void) {
+    return {{ static_.c_val }};
+}
+{%- else +%}
+typedef {{ static_.volatile_keyword }}{{ static_.c_mutable }}{{ static_.return_type }};
+ctest_static_ty__{{ static_.id }} ctest_static__{{ static_.id }}(void) {
+    return &{{ static_.c_val }};
+}


Since these return pointers, can they cast them on the C side and return void *? Rather than needing the more complex definition

@mbyx this one still needs to be changed. It's also checking for an extern substring still.

The change should look something like #4594 (comment) for the function pointer part.

ctest-next/templates/test.rs

ctest-next/src/template.rs

tgross35 · 2025-08-11T07:42:13Z

ctest-next/src/lib.rs

+/* A simple helper to find any nested bare fn types, such as `Option<unsafe extern "C" fn()>` */
+
+struct BareFnFinder {


This can be a doc comment on the struct

tgross35 · 2025-08-11T07:45:04Z

ctest-next/src/template.rs

+    pub mutable: BoxStr,
+    pub c_mutable: BoxStr,


Nit: these can be &'static str

tgross35 · 2025-08-11T07:54:32Z

ctest-next/templates/test.c

+{%- if static_.rust_ty.contains("extern") +%}
+typedef {{ static_.return_type }};
+ctest_static_ty__{{ static_.id }} ctest_static__{{ static_.id }}(void) {
+    return {{ static_.c_val }};
+}
+{%- else +%}
+typedef {{ static_.volatile_keyword }}{{ static_.c_mutable }}{{ static_.return_type }};
+ctest_static_ty__{{ static_.id }} ctest_static__{{ static_.id }}(void) {
+    return &{{ static_.c_val }};
+}


@mbyx this one still needs to be changed. It's also checking for an extern substring still.

The change should look something like #4594 (comment) for the function pointer part.

tgross35 · 2025-08-11T07:56:09Z

ctest-next/templates/test.rs

+        let actual = unsafe {
+            std::mem::transmute::<_, *const ()>(*(&raw const {{ static_.id }})).addr()
+        };
+        let expected = unsafe {
+            std::mem::transmute::<_, *const ()>(ctest_static__{{ static_.id }}()).addr()


Add self to the import at https://github.com/mbyx/libc/blob/494e5e5627035b847984501faaa8d34e4c40a9d4/ctest-next/templates/test.rs#L19

tgross35 · 2025-08-11T07:58:23Z

ctest-next/templates/test.rs

+        let actual = unsafe {
+            std::mem::transmute::<_, *const ()>(*(&raw const {{ static_.id }})).addr()
+        };
+        let expected = unsafe {
+            std::mem::transmute::<_, *const ()>(ctest_static__{{ static_.id }}()).addr()


Please add comments, this is tricky. Also, make sure this branch is covered in one of the tests.

tgross35

LGTM! What happened part with special handling for functions?

mbyx · 2025-08-11T12:24:25Z

Now it always returns a pointer to something, whether its a data item or a function pointer/array, etc. So the Rust side just checks for equality of addresses. I'm not sure if that's perfectly correct though.

tgross35 · 2025-08-11T14:23:26Z

Ah, I didn't catch that - it will work but it technically isn't correct because of the function->data pointer cast. I don't think we need to deal with it now, could you make that a FIXME?

We should enable warnings in the C builds at some point, at least during testing, -Wpedantic catches that.

tgross35

LGTM! Unfortunately CI is still blocked

rustbot added ctest Issues relating to the ctest crate S-waiting-on-review labels Jul 30, 2025

mbyx force-pushed the ctest-static-test branch 2 times, most recently from 6df4113 to 4455b42 Compare August 2, 2025 13:27

mbyx force-pushed the ctest-static-test branch from 4455b42 to aa88d90 Compare August 6, 2025 12:31

tgross35 reviewed Aug 6, 2025

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mbyx force-pushed the ctest-static-test branch from aa88d90 to c0fa242 Compare August 6, 2025 12:35

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libc-test: port windows to use ctest-next #4600

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mbyx force-pushed the ctest-static-test branch from c0fa242 to 494e5e5 Compare August 11, 2025 07:01

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ctest: add foreign static test

1685c18

mbyx force-pushed the ctest-static-test branch from c0b5f23 to 1685c18 Compare August 11, 2025 18:38

mbyx requested a review from tgross35 August 11, 2025 18:39

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Merged via the queue into rust-lang:main with commit 3060925 Aug 11, 2025
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rustbot removed the S-waiting-on-review label Aug 11, 2025

tgross35 added the stable-unneeded This PR is applied to main but already exists on libc-0.2 label Sep 19, 2025

		/* A simple helper to find any nested bare fn types, such as `Option<unsafe extern "C" fn()>` */

		struct BareFnFinder {

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mbyx commented Jul 30, 2025

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