ctest: add defines for specific headers and language selection

ctest/src/generator.rs

@@ -13,8 +13,8 @@ use crate::ffi_items::FfiItems;
 use crate::template::{CTestTemplate, RustTestTemplate};
 use crate::translator::translate_primitive_type;
 use crate::{
-    Const, Field, MapInput, Parameter, Result, Static, Struct, TranslationError, Type, Union,
-    VolatileItemKind, expand, get_build_target,
+    BoxStr, Const, Field, Language, MapInput, Parameter, Result, Static, Struct, TranslationError,
+    Type, Union, VolatileItemKind, expand, get_build_target,
 };
 
 /// A function that takes a mappable input and returns its mapping as `Some`, otherwise
@@ -35,14 +35,16 @@ type CEnum = Box<dyn Fn(&str) -> bool>;
 #[derive(Default)]
 #[expect(missing_debug_implementations)]
 pub struct TestGenerator {
-    pub(crate) headers: Vec<String>,
+    pub(crate) headers: Vec<(BoxStr, Vec<BoxStr>)>,
     pub(crate) target: Option<String>,
     pub(crate) includes: Vec<PathBuf>,
     out_dir: Option<PathBuf>,
     pub(crate) flags: Vec<String>,
-    pub(crate) defines: Vec<(String, Option<String>)>,
+    pub(crate) global_defines: Vec<(String, Option<String>)>,
     cfg: Vec<(String, Option<String>)>,
     mapped_names: Vec<MappedName>,
+    /// The programming language to generate tests in.
+    pub(crate) language: Language,
     pub(crate) skips: Vec<Skip>,
     pub(crate) verbose_skip: bool,
     pub(crate) volatile_items: Vec<VolatileItem>,
@@ -100,7 +102,53 @@ impl TestGenerator {
     ///    .header("bar.h");
     /// ```
     pub fn header(&mut self, header: &str) -> &mut Self {
-        self.headers.push(header.to_string());
+        self.headers.push((header.into(), vec![]));
+        self
+    }
+
+    /// Add a header to be included as part of the generated C file, as well as defines for it.
+    ///
+    /// The generated C test will be compiled by a C compiler, and this can be
+    /// used to ensure that all the necessary header files are included to test
+    /// all FFI definitions. The defines are only set for the inclusion of that header file, and are
+    /// undefined immediately after.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use ctest::TestGenerator;
+    ///
+    /// let mut cfg = TestGenerator::new();
+    /// cfg.header_with_defines("foo.h", Vec::<String>::new())
+    ///    .header_with_defines("bar.h", vec!["DEBUG", "DEPRECATED"]);
+    /// ```
+    pub fn header_with_defines(
+        &mut self,
+        header: &str,
+        defines: impl IntoIterator<Item = impl AsRef<str>>,
+    ) -> &mut Self {
+        self.headers.push((
+            header.into(),
+            defines.into_iter().map(|d| d.as_ref().into()).collect(),
+        ));
+        self
+    }
+
+    /// Sets the programming language, by default it is C.
+    ///
+    /// This determines what compiler is chosen to compile the C/C++ tests, as well as adding
+    /// external linkage to the tests if set to C++, so that they can be used in Rust.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use ctest::{TestGenerator, Language};
+    ///
+    /// let mut cfg = TestGenerator::new();
+    /// cfg.language(Language::CXX);
+    /// ```
+    pub fn language(&mut self, language: Language) -> &mut Self {
+        self.language = language;
         self
     }
 
@@ -585,7 +633,7 @@ impl TestGenerator {
 
     /// Set a `-D` flag for the C compiler being called.
     ///
-    /// This can be used to define various variables to configure how header
+    /// This can be used to define various global variables to configure how header
     /// files are included or what APIs are exposed from header files.
     ///
     /// # Examples
@@ -598,7 +646,7 @@ impl TestGenerator {
     ///    .define("_WIN32_WINNT", Some("0x8000"));
     /// ```
     pub fn define(&mut self, k: &str, v: Option<&str>) -> &mut Self {
-        self.defines
+        self.global_defines
             .push((k.to_string(), v.map(std::string::ToString::to_string)));
         self
     }
@@ -999,7 +1047,7 @@ impl TestGenerator {
         ensure_trailing_newline(&mut c_file);
 
         // Generate the C/Cxx side of the tests.
-        let c_output_path = output_file_path.with_extension("c");
+        let c_output_path = output_file_path.with_extension(self.language.extension());
         File::create(&c_output_path)
             .map_err(GenerationError::OsError)?
             .write_all(c_file.as_bytes())

ctest/src/lib.rs

@@ -78,6 +78,27 @@ pub(crate) enum MapInput<'a> {
     UnionFieldType(&'a Union, &'a Field),
 }
 
+/// The language used to generate the tests.
+#[derive(Debug, Default, Clone)]
+#[non_exhaustive]
+pub enum Language {
+    /// The C Programming Language.
+    #[default]
+    C,
+    /// The C++ Programming Language.
+    CXX,
+}
+
+impl Language {
+    /// Return the file extension of the programming language.
+    pub(crate) fn extension(&self) -> &str {
+        match self {
+            Self::C => "c",
+            Self::CXX => "cpp",
+        }
+    }
+}
+
 /// Search for the target to build for, specified manually or through an environment variable.
 ///
 /// This function will check the following places for the target name:

ctest/src/runner.rs

@@ -7,7 +7,7 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 
 use crate::generator::GenerationError;
-use crate::{EDITION, Result, TestGenerator, get_build_target};
+use crate::{EDITION, Language, Result, TestGenerator, get_build_target};
 
 /// Generate all tests for the given crate and output the Rust side to a file.
 #[doc(hidden)]
@@ -24,7 +24,7 @@ pub fn generate_test(
         .map_err(|_| GenerationError::EnvVarNotFound("HOST, HOST_PLATFORM".to_string()))?;
 
     let mut cfg = cc::Build::new();
-    cfg.file(output_file_path.with_extension("c"));
+    cfg.file(output_file_path.with_extension(generator.language.extension()));
     cfg.host(&host);
 
     if target.contains("msvc") {
@@ -64,10 +64,12 @@ pub fn generate_test(
         cfg.flag(flag);
     }
 
-    for (k, v) in &generator.defines {
+    for (k, v) in &generator.global_defines {
         cfg.define(k, v.as_ref().map(|s| &s[..]));
     }
 
+    cfg.cpp(matches!(generator.language, Language::CXX));
+
     let stem: &str = output_file_path.file_stem().unwrap().to_str().unwrap();
     cfg.target(&target)
         .out_dir(output_file_path.parent().unwrap())

ctest/src/template.rs

@@ -35,7 +35,7 @@ impl RustTestTemplate {
 #[template(path = "test.c")]
 pub(crate) struct CTestTemplate {
     pub template: TestTemplate,
-    pub headers: Vec<String>,
+    pub headers: Vec<(BoxStr, Vec<BoxStr>)>,
 }
 
 impl CTestTemplate {

ctest/templates/test.c

@@ -8,11 +8,25 @@
 #include <stdint.h>
 #include <stdio.h>
 
-{%- for header in self.headers +%}
+{%- for (header, defines) in self.headers +%}
+{%- for define in defines +%}
 
+#define {{ define }}
+{%- endfor +%}
 #include <{{ header }}>
+{%- for define in defines +%}
+#undef {{ define }}
+{%- endfor +%}
 {%- endfor +%}
 
+#if defined(__cplusplus)
+    #define CTEST_ALIGNOF(T) alignof(T)
+    #define CTEST_EXTERN extern "C" 
+#else
+    #define CTEST_ALIGNOF(T) _Alignof(T)
+    #define CTEST_EXTERN
+#endif
+
 typedef void (*ctest_void_func)(void);
 
 {%- for const_cstr in ctx.const_cstr_tests +%}
@@ -21,7 +35,7 @@ static char *ctest_const_{{ const_cstr.id }}_val_static = {{ const_cstr.c_val }}
 
 // Define a function that returns a pointer to the value of the constant to test.
 // This will later be called on the Rust side via FFI.
-char *ctest_const_cstr__{{ const_cstr.id }}(void) {
+CTEST_EXTERN char *ctest_const_cstr__{{ const_cstr.id }}(void) {
     return ctest_const_{{ const_cstr.id }}_val_static;
 }
 {%- endfor +%}
@@ -32,25 +46,25 @@ static {{ constant.c_ty }} ctest_const_{{ constant.id }}_val_static = {{ constan
 
 // Define a function that returns a pointer to the value of the constant to test.
 // This will later be called on the Rust side via FFI.
-{{ constant.c_ty }} *ctest_const__{{ constant.id }}(void) {
+CTEST_EXTERN {{ constant.c_ty }} *ctest_const__{{ constant.id }}(void) {
     return &ctest_const_{{ constant.id }}_val_static;
 }
 {%- endfor +%}
 
 {%- for item in ctx.size_align_tests +%}
 
 // Return the size of a type.
-uint64_t ctest_size_of__{{ item.id }}(void) { return sizeof({{ item.c_ty }}); }
+CTEST_EXTERN uint64_t ctest_size_of__{{ item.id }}(void) { return sizeof({{ item.c_ty }}); }
 
 // Return the alignment of a type.
-uint64_t ctest_align_of__{{ item.id }}(void) { return _Alignof({{ item.c_ty }}); }
+CTEST_EXTERN uint64_t ctest_align_of__{{ item.id }}(void) { return CTEST_ALIGNOF({{ item.c_ty }}); }
 {%- endfor +%}
 
 {%- for alias in ctx.signededness_tests +%}
 
 // Return `1` if the type is signed, otherwise return `0`.
 // Casting -1 to the aliased type if signed evaluates to `-1 < 0`, if unsigned to `MAX_VALUE < 0`
-uint32_t ctest_signededness_of__{{ alias.id }}(void) {
+CTEST_EXTERN uint32_t ctest_signededness_of__{{ alias.id }}(void) {
     {{ alias.c_ty }} all_ones = ({{ alias.c_ty }}) -1;
     return all_ones < 0;
 }
@@ -59,12 +73,12 @@ uint32_t ctest_signededness_of__{{ alias.id }}(void) {
 {%- for item in ctx.field_size_offset_tests +%}
 
 // Return the offset of a struct/union field.
-uint64_t ctest_offset_of__{{ item.id }}__{{ item.field.ident() }}(void) {
+CTEST_EXTERN uint64_t ctest_offset_of__{{ item.id }}__{{ item.field.ident() }}(void) {
     return offsetof({{ item.c_ty }}, {{ item.c_field }});
 }
 
 // Return the size of a struct/union field.
-uint64_t ctest_size_of__{{ item.id }}__{{ item.field.ident() }}(void) {
+CTEST_EXTERN uint64_t ctest_size_of__{{ item.id }}__{{ item.field.ident() }}(void) {
     return sizeof((({{ item.c_ty }}){}).{{ item.c_field }});
 }
 {%- endfor +%}
@@ -75,7 +89,7 @@ uint64_t ctest_size_of__{{ item.id }}__{{ item.field.ident() }}(void) {
 // This field can have a normal data type, or it could be a function pointer or an array, which
 // have different syntax. A typedef is used for convenience, but the syntax must be precomputed.
 typedef {{ item.volatile_keyword }}{{ item.field_return_type }};
-ctest_field_ty__{{ item.id }}__{{ item.field.ident() }}
+CTEST_EXTERN ctest_field_ty__{{ item.id }}__{{ item.field.ident() }}
 ctest_field_ptr__{{ item.id }}__{{ item.field.ident() }}({{ item.c_ty }} *b) {
     return &b->{{ item.c_field }};
 }
@@ -92,7 +106,7 @@ ctest_field_ptr__{{ item.id }}__{{ item.field.ident() }}({{ item.c_ty }} *b) {
 // Tests whether the struct/union/alias `x` when passed by value to C and back to Rust
 // remains unchanged.
 // It checks if the size is the same as well as if the padding bytes are all in the correct place.
-{{ item.c_ty }} ctest_roundtrip__{{ item.id }}(
+CTEST_EXTERN {{ item.c_ty }} ctest_roundtrip__{{ item.id }}(
     {{ item.c_ty }} value,
     const uint8_t is_padding_byte[sizeof({{ item.c_ty }})],
     uint8_t value_bytes[sizeof({{ item.c_ty }})]
@@ -130,7 +144,8 @@ ctest_field_ptr__{{ item.id }}__{{ item.field.ident() }}({{ item.c_ty }} *b) {
 
 {%- for item in ctx.foreign_fn_tests +%}
 
-ctest_void_func ctest_foreign_fn__{{ item.id }}(void) {
+// Return a function pointer.
+CTEST_EXTERN ctest_void_func ctest_foreign_fn__{{ item.id }}(void) {
     return (ctest_void_func){{ item.c_val }};
 }
 {%- endfor +%}
@@ -142,7 +157,7 @@ ctest_void_func ctest_foreign_fn__{{ item.id }}(void) {
 {%- for static_ in ctx.foreign_static_tests +%}
 
 // Return a pointer to the static variable content.
-void *ctest_static__{{ static_.id }}(void) {
+CTEST_EXTERN void *ctest_static__{{ static_.id }}(void) {
     // FIXME(ctest): Not correct due to casting the function to a data pointer.
     return (void *)&{{ static_.c_val }};
 }

ctest/tests/basic.rs

@@ -11,15 +11,18 @@ use pretty_assertions::assert_eq;
 ///
 /// The files will be generated in a unique temporary directory that gets
 /// deleted when it goes out of scope.
-fn default_generator(opt_level: u8, header: &str) -> Result<(TestGenerator, tempfile::TempDir)> {
+fn default_generator(
+    opt_level: u8,
+    header: Option<&str>,
+) -> Result<(TestGenerator, tempfile::TempDir)> {
     // FIXME(mbyx): Remove this in favor of not-unsafe alternatives.
     unsafe { env::set_var("OPT_LEVEL", opt_level.to_string()) };
     let temp_dir = tempfile::tempdir()?;
     let mut generator = TestGenerator::new();
-    generator
-        .out_dir(&temp_dir)
-        .include("tests/input")
-        .header(header);
+    generator.out_dir(&temp_dir).include("tests/input");
+    if let Some(header) = header {
+        generator.header(header);
+    }
 
     Ok((generator, temp_dir))
 }
@@ -84,7 +87,7 @@ fn test_entrypoint_hierarchy() {
     let crate_path = include_path.join("hierarchy/lib.rs");
     let library_path = "hierarchy.out.a";
 
-    let (mut gen_, out_dir) = default_generator(1, "hierarchy.h").unwrap();
+    let (mut gen_, out_dir) = default_generator(1, Some("hierarchy.h")).unwrap();
     check_entrypoint(&mut gen_, out_dir, crate_path, library_path, include_path);
 }
 
@@ -95,7 +98,7 @@ fn test_skip_simple() {
     let crate_path = include_path.join("simple.rs");
     let library_path = "simple.out.with-skips.a";
 
-    let (mut gen_, out_dir) = default_generator(1, "simple.h").unwrap();
+    let (mut gen_, out_dir) = default_generator(1, Some("simple.h")).unwrap();
     gen_.skip_const(|c| c.ident() == "B" || c.ident() == "A")
         .skip_c_enum(|e| e == "Color")
         .skip_alias(|a| a.ident() == "Byte")
@@ -114,7 +117,7 @@ fn test_map_simple() {
     let crate_path = include_path.join("simple.rs");
     let library_path = "simple.out.with-renames.a";
 
-    let (mut gen_, out_dir) = default_generator(1, "simple.h").unwrap();
+    let (mut gen_, out_dir) = default_generator(1, Some("simple.h")).unwrap();
     gen_.rename_constant(|c| (c.ident() == "B").then(|| "C_B".to_string()))
         .alias_is_c_enum(|e| e == "Color")
         .skip_signededness(|ty| ty == "Color");
@@ -129,7 +132,9 @@ fn test_entrypoint_macro() {
     let crate_path = include_path.join("macro.rs");
     let library_path = "macro.out.a";
 
-    let (mut gen_, out_dir) = default_generator(1, "macro.h").unwrap();
+    let (mut gen_, out_dir) = default_generator(1, None).unwrap();
+    gen_.header_with_defines("macro.h", vec!["SUPPRESS_ERROR"]);
+
     check_entrypoint(&mut gen_, out_dir, crate_path, library_path, include_path);
 }
 

ctest/tests/input/hierarchy.h

@@ -1,6 +1,10 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#ifdef SUPPRESS_ERROR
+#error Expected SUPPRESS_ERROR to not be defined (testing per-file defines)
+#endif
+
 typedef unsigned int in6_addr;
 
 #define ON true