Cxxbuild set std.upstream

BUILD

@@ -50,6 +50,11 @@ rust_library(
     ],
 )
 
+rust_library(
+    name = "cxxbridge-flags",
+    srcs = glob(["flags/src/*.rs"]),
+)
+
 rust_library(
     name = "build",
     srcs = glob(["gen/build/src/**/*.rs"]),
@@ -61,6 +66,7 @@ rust_library(
         "//third-party:proc-macro2",
         "//third-party:quote",
         "//third-party:syn",
+        "//:cxxbridge-flags",
     ],
 )
 

README.md

@@ -212,6 +212,11 @@ For builds that are orchestrated by Cargo, you will use a build script that runs
 CXX's C++ code generator and compiles the resulting C++ code along with any
 other C++ code for your crate.
 
+CXX create features, such as support of a different C++ standard, are
+automatically set if using cxx_build. This ensures that your code gets
+compiled with the same feature flags as the CXX bridge library code in
+cxx.h|cc. See the CXX crate for available features.
+
 The canonical build script is as follows. The indicated line returns a
 [`cc::Build`] instance (from the usual widely used `cc` crate) on which you can
 set up any additional source files and compiler flags as normal.
@@ -221,6 +226,11 @@ set up any additional source files and compiler flags as normal.
 ```toml
 # Cargo.toml
 
+[dependencies]
+cxx = "0.4"
+# To pick a different C++ standard:
+# cxx = { version = "0.4", features = ["c++14"] }
+
 [build-dependencies]
 cxx-build = "0.4"
 ```
@@ -231,7 +241,6 @@ cxx-build = "0.4"
 fn main() {
     cxx_build::bridge("src/main.rs")  // returns a cc::Build
         .file("src/demo.cc")
-        .flag_if_supported("-std=c++11")
         .compile("cxxbridge-demo");
 
     println!("cargo:rerun-if-changed=src/main.rs");

demo/Cargo.toml

@@ -6,7 +6,8 @@ edition = "2018"
 publish = false
 
 [dependencies]
-cxx = { path = ".." }
+cxx = { path = "..", features= ["c++14"] }
 
 [build-dependencies]
 cxx-build = { path = "../gen/build" }
+

demo/build.rs

@@ -1,7 +1,6 @@
 fn main() {
     cxx_build::bridge("src/main.rs")
         .file("src/demo.cc")
-        .flag_if_supported("-std=c++14")
         .compile("cxxbridge-demo");
 
     println!("cargo:rerun-if-changed=src/main.rs");

gen/build/Cargo.toml

@@ -16,6 +16,7 @@ codespan-reporting = "0.9"
 proc-macro2 = { version = "1.0.17", default-features = false, features = ["span-locations"] }
 quote = { version = "1.0", default-features = false }
 syn = { version = "1.0.20", default-features = false, features = ["parsing", "printing", "clone-impls", "full"] }
+cxxbridge-flags = { version = "=0.4.7", path = "../../flags", default-features = false }
 
 [dev-dependencies]
 cxx-gen = { version = "0.4", path = "../lib" }

gen/build/src/lib.rs

@@ -4,6 +4,11 @@
 //! C++ code generator, set up any additional compiler flags depending on
 //! the use case, and make the C++ compiler invocation.
 //!
+//! CXX create features, such as support of a different C++ standard, are
+//! automatically set if using cxx_build. This ensures that your code gets
+//! compiled with the same feature flags as the CXX bridge library code in
+//! cxx.h|cc. See the CXX crate for available features.
+//!
 //! <br>
 //!
 //! # Example
@@ -16,7 +21,6 @@
 //! fn main() {
 //!     cxx_build::bridge("src/main.rs")
 //!         .file("src/demo.cc")
-//!         .flag_if_supported("-std=c++11")
 //!         .compile("cxxbridge-demo");
 //!
 //!     println!("cargo:rerun-if-changed=src/main.rs");
@@ -87,7 +91,6 @@ pub fn bridge(rust_source_file: impl AsRef<Path>) -> Build {
 /// let source_files = vec!["src/main.rs", "src/path/to/other.rs"];
 /// cxx_build::bridges(source_files)
 ///     .file("src/demo.cc")
-///     .flag_if_supported("-std=c++11")
 ///     .compile("cxxbridge-demo");
 /// ```
 #[must_use]
@@ -129,6 +132,8 @@ fn build(rust_source_files: &mut dyn Iterator<Item = impl AsRef<Path>>) -> Resul
     build.cpp(true);
     build.cpp_link_stdlib(None); // linked via link-cplusplus crate
     build.include(&include_dir);
+    // Set feature parameters, such as C++ std, for simpler usage
+    build.flag_if_supported(cxxbridge_flags::STD);
     write_header(prj);
     let crate_dir = symlink_crate(prj, &mut build);
 

src/lib.rs

@@ -218,6 +218,11 @@
 //! runs CXX's C++ code generator and compiles the resulting C++ code along with
 //! any other C++ code for your crate.
 //!
+//! CXX create features, such as support of a different C++ standard, are
+//! automatically set if using cxx_build. This ensures that your code gets
+//! compiled with the same feature flags as the CXX bridge library code in
+//! cxx.h|cc. See the CXX crate for available features.
+//!
 //! The canonical build script is as follows. The indicated line returns a
 //! [`cc::Build`] instance (from the usual widely used `cc` crate) on which you
 //! can set up any additional source files and compiler flags as normal.
@@ -227,6 +232,11 @@
 //! ```toml
 //! # Cargo.toml
 //!
+//! [dependencies]
+//! cxx = "0.4"
+//! # To pick a different C++ standard:
+//! # cxx = { version = "0.4", features = ["c++14"] }
+//!
 //! [build-dependencies]
 //! cxx-build = "0.4"
 //! ```
@@ -237,7 +247,6 @@
 //! fn main() {
 //!     cxx_build::bridge("src/main.rs")  // returns a cc::Build
 //!         .file("src/demo.cc")
-//!         .flag_if_supported("-std=c++11")
 //!         .compile("cxxbridge-demo");
 //!
 //!     println!("cargo:rerun-if-changed=src/main.rs");

tests/ffi/Cargo.toml

@@ -12,4 +12,3 @@ cxx = { path = "../.." }
 
 [build-dependencies]
 cxx-build = { path = "../../gen/build" }
-cxxbridge-flags = { path = "../../flags" }

tests/ffi/build.rs

@@ -6,6 +6,5 @@ fn main() {
     let sources = vec!["lib.rs", "module.rs"];
     cxx_build::bridges(sources)
         .file("tests.cc")
-        .flag_if_supported(cxxbridge_flags::STD)
         .compile("cxx-test-suite");
 }