Add no_exceptions feature flag

Cargo.toml

@@ -19,6 +19,7 @@ default = ["std", "cxxbridge-flags/default"] # c++11
 "c++14" = ["cxxbridge-flags/c++14"]
 "c++17" = ["cxxbridge-flags/c++17"]
 "c++20" = ["cxxbridge-flags/c++20"]
+"no_exceptions" = ["cxxbridge-flags/no_exceptions"]
 alloc = []
 std = ["alloc"]
 

build.rs

@@ -11,6 +11,7 @@ fn main() {
         .cpp(true)
         .cpp_link_stdlib(None) // linked via link-cplusplus crate
         .std(cxxbridge_flags::STD)
+        .define(cxxbridge_flags::EXCEPTIONS, None)
         .warnings_into_errors(cfg!(deny_warnings))
         .compile("cxxbridge1");
 

flags/Cargo.toml

@@ -14,6 +14,7 @@ default = [] # c++11
 "c++14" = []
 "c++17" = []
 "c++20" = []
+"no_exceptions" = []
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

flags/src/impl.rs

@@ -1,4 +1,4 @@
-#[allow(unused_assignments, unused_mut, unused_variables)]
+#![allow(unused_assignments, unused_mut, unused_variables)]
 pub const STD: &str = {
     let mut flag = "c++11";
 
@@ -13,3 +13,12 @@ pub const STD: &str = {
 
     flag
 };
+
+pub const EXCEPTIONS: &str = {
+    let mut flag = "RUST_CXX_ALLOW_EXCEPTIONS";
+
+    #[cfg(feature = "no_exceptions")]
+    (flag = "RUST_CXX_NO_EXCEPTIONS");
+
+    flag
+};