From 0182bb041ff422d53c66306e231894d75bc50bca Mon Sep 17 00:00:00 2001
From: Christian Poveda <christian.poveda@ferrous-systems.com>
Date: Fri, 9 Sep 2022 10:58:12 -0500
Subject: [PATCH] add `--cxx` flag

---
 bindgen-cli/options.rs                                   | 7 +++++++
 bindgen-tests/tests/headers/dash_language.h              | 2 +-
 .../tests/headers/dupe-enum-variant-in-namespace.h       | 2 +-
 bindgen-tests/tests/headers/empty-enum.h                 | 2 +-
 bindgen-tests/tests/headers/packed-vtable.h              | 2 +-
 bindgen/lib.rs                                           | 6 ++++++
 book/src/cpp.md                                          | 9 ++++-----
 7 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/bindgen-cli/options.rs b/bindgen-cli/options.rs
index 5c3960e92b..ed4bffbb50 100644
--- a/bindgen-cli/options.rs
+++ b/bindgen-cli/options.rs
@@ -568,6 +568,9 @@ where
             Arg::new("merge-extern-blocks")
                 .long("merge-extern-blocks")
                 .help("Deduplicates extern blocks."),
+            Arg::new("cxx")
+                .long("cxx")
+                .help("Enables parsing C++ headers."),
             Arg::new("V")
                 .long("version")
                 .help("Prints the version, and exits"),
@@ -1088,5 +1091,9 @@ where
         builder = builder.merge_extern_blocks(true);
     }
 
+    if matches.is_present("cxx") {
+        builder = builder.cxx();
+    }
+
     Ok((builder, output, verbose))
 }
diff --git a/bindgen-tests/tests/headers/dash_language.h b/bindgen-tests/tests/headers/dash_language.h
index 4c8bb58dd7..531e54f2e0 100644
--- a/bindgen-tests/tests/headers/dash_language.h
+++ b/bindgen-tests/tests/headers/dash_language.h
@@ -1,4 +1,4 @@
-// bindgen-flags: -- -x c++ --std=c++11
+// bindgen-flags: --cxx -- --std=c++11
 
 template<typename T>
 struct Foo {
diff --git a/bindgen-tests/tests/headers/dupe-enum-variant-in-namespace.h b/bindgen-tests/tests/headers/dupe-enum-variant-in-namespace.h
index 2b6fb93a8e..7f9539dfdb 100644
--- a/bindgen-tests/tests/headers/dupe-enum-variant-in-namespace.h
+++ b/bindgen-tests/tests/headers/dupe-enum-variant-in-namespace.h
@@ -1,4 +1,4 @@
-// bindgen-flags: --rustified-enum ".*" --enable-cxx-namespaces -- -x c++ -std=c++11
+// bindgen-flags: --rustified-enum ".*" --enable-cxx-namespaces --cxx -- -std=c++11
 
 namespace foo {
   enum class Bar : unsigned {
diff --git a/bindgen-tests/tests/headers/empty-enum.h b/bindgen-tests/tests/headers/empty-enum.h
index 8b7502e671..8735eeff6c 100644
--- a/bindgen-tests/tests/headers/empty-enum.h
+++ b/bindgen-tests/tests/headers/empty-enum.h
@@ -1,4 +1,4 @@
-// bindgen-flags: --rustified-enum '.*Rustified.*' --constified-enum-module '.*Module.*' -- -x c++ --std=c++14
+// bindgen-flags: --rustified-enum '.*Rustified.*' --constified-enum-module '.*Module.*' --cxx -- --std=c++14
 
 // Constified is default, so no flag for that.
 
diff --git a/bindgen-tests/tests/headers/packed-vtable.h b/bindgen-tests/tests/headers/packed-vtable.h
index d2413d4571..6584dead82 100644
--- a/bindgen-tests/tests/headers/packed-vtable.h
+++ b/bindgen-tests/tests/headers/packed-vtable.h
@@ -1,4 +1,4 @@
-// bindgen-flags: --raw-line '#![cfg(feature = "nightly")]' --rust-target 1.33 -- -x c++ -std=c++11
+// bindgen-flags: --raw-line '#![cfg(feature = "nightly")]' --rust-target 1.33 --cxx -- -std=c++11
 
 #pragma pack(1)
 
diff --git a/bindgen/lib.rs b/bindgen/lib.rs
index 6e6fa225d6..e64218e7cd 100644
--- a/bindgen/lib.rs
+++ b/bindgen/lib.rs
@@ -1323,6 +1323,12 @@ impl Builder {
         self
     }
 
+    /// Tell `clang` that the input files are `c++` files.
+    #[inline]
+    pub fn cxx(self) -> Builder {
+        self.clang_args(["-x", "c++"])
+    }
+
     /// Enable detecting must_use attributes on C functions.
     ///
     /// This is quite slow in some cases (see #1465), so it's disabled by
diff --git a/book/src/cpp.md b/book/src/cpp.md
index 75ef855494..d7a69a5cbb 100644
--- a/book/src/cpp.md
+++ b/book/src/cpp.md
@@ -7,9 +7,8 @@ be nowhere near as nice as using them in C++. You will have to manually call
 constructors, destructors, overloaded operators, etc yourself.
 
 When passing in header files, the file will automatically be treated as C++ if
-it ends in `.hpp`. If it doesn't, adding `-x c++` clang args can be used to
-force C++ mode. You probably also want to use `-std=c++14` or similar clang args
-as well.
+it ends in `.hpp`. If it doesn't, adding the `--cxx` flag will force C++ mode.
+You probably also want to use the clang arg `-std=c++14` or similar as well.
 
 You pretty much **must** use [allowlisting](./allowlisting.md) when working
 with C++ to avoid pulling in all of the `std::.*` types, many of which `bindgen`
@@ -71,8 +70,8 @@ cannot translate into Rust:
   generate undefined behaviour. See
   [the tracking issue for exceptions](https://github.com/rust-lang/rust-bindgen/issues/1208)
   for more details.
-  
+
 * Return value optimization. C++ compilers will in certain circumstances optimize functions
   returning a struct type value to instead take an extra hidden argument that refers
   to the return value struct. `bindgen` cannot necessarily know about this optimization and
-  thus at present `bindgen`-interfaces for these kinds of functions are invalid. 
+  thus at present `bindgen`-interfaces for these kinds of functions are invalid.