Add support for -fXX feature flags

include/cppast/compile_config.hpp

@@ -74,6 +74,13 @@ public:
         do_set_flags(standard, flags);
     }
 
+    /// \effects Enables an `-fXXX` flag.
+    /// \returns Whether or not it was a known feature and enabled.
+    bool enable_feature(std::string name)
+    {
+        return do_enable_feature(name);
+    }
+
     /// \effects Adds the given path to the set of include directories.
     void add_include_dir(std::string path)
     {
@@ -121,6 +128,14 @@ private:
     /// \effects Sets the given C++ standard and compilation flags.
     virtual void do_set_flags(cpp_standard standard, compile_flags flags) = 0;
 
+    /// \effects Sets the given feature flags.
+    /// \returns Whether or not it was a known feature and set.
+    virtual bool do_enable_feature(std::string name)
+    {
+        (void)name;
+        return false;
+    }
+
     /// \effects Adds the given path to the set of include directories.
     virtual void do_add_include_dir(std::string path) = 0;
 

include/cppast/libclang_parser.hpp

@@ -157,6 +157,8 @@ public:
 private:
     void do_set_flags(cpp_standard standard, compile_flags flags) override;
 
+    bool do_enable_feature(std::string name) override;
+
     void do_add_include_dir(std::string path) override;
 
     void do_add_macro_definition(std::string name, std::string definition) override;

src/libclang/libclang_parser.cpp

@@ -386,6 +386,12 @@ void libclang_compile_config::do_set_flags(cpp_standard standard, compile_flags
         add_flag("-fms-extensions");
 }
 
+bool libclang_compile_config::do_enable_feature(std::string name)
+{
+    add_flag("-f" + std::move(name));
+    return true;
+}
+
 void libclang_compile_config::do_add_include_dir(std::string path)
 {
     add_flag("-I" + std::move(path));