ctest: check incompatible pointer types for public fields.

Author: mbyx

ctest/src/generator.rs

@@ -124,6 +124,8 @@ pub enum GenerationError {
     OsError(std::io::Error),
     #[error("one of {0} environment variable(s) not set")]
     EnvVarNotFound(String),
+    #[error("unable to compile C tests {0}")]
+    CompileError(cc::Error),
 }
 
 impl TestGenerator {

ctest/src/runner.rs

@@ -92,7 +92,8 @@ pub fn generate_test(
 
     let stem: &str = output_file_path.file_stem().unwrap().to_str().unwrap();
     cfg.out_dir(output_file_path.parent().unwrap())
-        .compile(stem);
+        .try_compile(stem)
+        .map_err(GenerationError::CompileError)?;
 
     Ok(output_file_path)
 }

ctest/templates/test.c

@@ -104,6 +104,14 @@ CTEST_EXTERN uint64_t ctest_size_of__{{ item.id }}__{{ item.field.ident() }}(voi
 typedef {{ item.volatile_keyword }}{{ item.field_return_type }};
 CTEST_EXTERN ctest_field_ty__{{ item.id }}__{{ item.field.ident() }}
 ctest_field_ptr__{{ item.id }}__{{ item.field.ident() }}({{ item.c_ty }} *b) {
+    {#
+        // In order to trigger -Wincompatible-pointer-types, we need to attempt to create a
+        // pointer to the given struct or field type, but using the type translated from Rust.
+    #}
+    ctest_field_ty__{{ item.id }}__{{ item.field.ident() }} ptr;
+    ptr = &b->{{ item.c_field }};
+    (void)ptr; {# avoid unused warnings #}
+
     return &b->{{ item.c_field }};
 }
 {%- endfor +%}

ctest/tests/basic.rs

@@ -210,3 +210,35 @@ fn test_raw_identifier_field() {
         assert!(result.is_ok());
     }
 }
+
+#[test]
+fn test_mismatched_union_field_ty() {
+    let include_path = PathBuf::from("tests/input");
+    let crate_path = include_path.join("mismatched_union_field_ty.rs");
+    let library_path = "mismatched_union_field_ty.out.a";
+
+    let (mut gen_, _out_dir) = default_generator(1, Some("mismatched_union_field_ty.h")).unwrap();
+
+    if env::var("TARGET_PLATFORM") == env::var("HOST_PLATFORM") {
+        let result = generate_test(&mut gen_, &crate_path, library_path);
+        assert!(result.is_err());
+        // As cc prints its warning/error messages to stderr, we cannot access them from cc::Error,
+        // and so cannot assert that the error was actually due to -Wincompatible-pointer-types.
+    }
+}
+
+#[test]
+fn test_mismatched_struct_field_ty() {
+    let include_path = PathBuf::from("tests/input");
+    let crate_path = include_path.join("mismatched_struct_field_ty.rs");
+    let library_path = "mismatched_struct_field_ty.out.a";
+
+    let (mut gen_, _out_dir) = default_generator(1, Some("mismatched_struct_field_ty.h")).unwrap();
+
+    if env::var("TARGET_PLATFORM") == env::var("HOST_PLATFORM") {
+        let result = generate_test(&mut gen_, &crate_path, library_path);
+        assert!(result.is_err());
+        // FIXME(ctest): As cc prints its warning/error messages to stderr, we cannot access them from cc::Error,
+        // and so cannot assert that the error was actually due to -Wincompatible-pointer-types.
+    }
+}

ctest/tests/input/macro.out.c

@@ -90,27 +90,47 @@ CTEST_EXTERN uint64_t ctest_size_of__VecU16__y(void) {
 typedef uint8_t *ctest_field_ty__VecU8__x;
 CTEST_EXTERN ctest_field_ty__VecU8__x
 ctest_field_ptr__VecU8__x(struct VecU8 *b) {
+    
+    ctest_field_ty__VecU8__x ptr;
+    ptr = &b->x;
+    (void)ptr; 
+
     return &b->x;
 }
 
 
 typedef uint8_t *ctest_field_ty__VecU8__y;
 CTEST_EXTERN ctest_field_ty__VecU8__y
 ctest_field_ptr__VecU8__y(struct VecU8 *b) {
+    
+    ctest_field_ty__VecU8__y ptr;
+    ptr = &b->y;
+    (void)ptr; 
+
     return &b->y;
 }
 
 
 typedef uint16_t *ctest_field_ty__VecU16__x;
 CTEST_EXTERN ctest_field_ty__VecU16__x
 ctest_field_ptr__VecU16__x(struct VecU16 *b) {
+    
+    ctest_field_ty__VecU16__x ptr;
+    ptr = &b->x;
+    (void)ptr; 
+
     return &b->x;
 }
 
 
 typedef uint16_t *ctest_field_ty__VecU16__y;
 CTEST_EXTERN ctest_field_ty__VecU16__y
 ctest_field_ptr__VecU16__y(struct VecU16 *b) {
+    
+    ctest_field_ty__VecU16__y ptr;
+    ptr = &b->y;
+    (void)ptr; 
+
     return &b->y;
 }
 

ctest/tests/input/macro.out.edition-2024.c

@@ -90,27 +90,47 @@ CTEST_EXTERN uint64_t ctest_size_of__VecU16__y(void) {
 typedef uint8_t *ctest_field_ty__VecU8__x;
 CTEST_EXTERN ctest_field_ty__VecU8__x
 ctest_field_ptr__VecU8__x(struct VecU8 *b) {
+    
+    ctest_field_ty__VecU8__x ptr;
+    ptr = &b->x;
+    (void)ptr; 
+
     return &b->x;
 }
 
 
 typedef uint8_t *ctest_field_ty__VecU8__y;
 CTEST_EXTERN ctest_field_ty__VecU8__y
 ctest_field_ptr__VecU8__y(struct VecU8 *b) {
+    
+    ctest_field_ty__VecU8__y ptr;
+    ptr = &b->y;
+    (void)ptr; 
+
     return &b->y;
 }
 
 
 typedef uint16_t *ctest_field_ty__VecU16__x;
 CTEST_EXTERN ctest_field_ty__VecU16__x
 ctest_field_ptr__VecU16__x(struct VecU16 *b) {
+    
+    ctest_field_ty__VecU16__x ptr;
+    ptr = &b->x;
+    (void)ptr; 
+
     return &b->x;
 }
 
 
 typedef uint16_t *ctest_field_ty__VecU16__y;
 CTEST_EXTERN ctest_field_ty__VecU16__y
 ctest_field_ptr__VecU16__y(struct VecU16 *b) {
+    
+    ctest_field_ty__VecU16__y ptr;
+    ptr = &b->y;
+    (void)ptr; 
+
     return &b->y;
 }
 

ctest/tests/input/mismatched_struct_field_ty.h

@@ -0,0 +1,18 @@
+#include <stdint.h>
+
+// The struct and union must match the size and alignment of the Rust side,
+// otherwise different warnings are emitted that hide -Wincompatible-pointer-types.
+struct Bar {
+    int16_t x;
+    int16_t y;
+};
+
+union Baz {
+    int32_t x;
+    float y;
+};
+
+struct Foo {
+    struct Bar a;
+    union Baz b;
+};

ctest/tests/input/mismatched_struct_field_ty.rs

@@ -0,0 +1,6 @@
+#[repr(C)]
+pub struct Foo {
+    // We use a 4 byte type with 4 byte alignment.
+    pub a: i32,
+    pub b: i32,
+}

ctest/tests/input/mismatched_union_field_ty.h

@@ -0,0 +1,8 @@
+#include <stdint.h>
+
+// The union must match the size and alignment of the Rust side,
+// otherwise different warnings are emitted that hide -Wincompatible-pointer-types.
+union Bar {
+    int64_t x;
+    int32_t y;
+};

ctest/tests/input/mismatched_union_field_ty.rs

@@ -0,0 +1,8 @@
+use core::ffi::c_float;
+
+// Union size is 8 bytes.
+#[repr(C)]
+union Bar {
+    pub x: i64,
+    pub y: c_float,
+}