do all the changes to BindgenState inside build

Author: pvdrz

src/lib.rs

@@ -1513,29 +1513,8 @@ impl Builder {
     }
 
     /// Generate the Rust bindings using the options built up thus far.
-    pub fn generate(mut self) -> Result<Bindings, BindgenError> {
-        let mut state = BindgenState::build(&self.options);
-        state.parse_callbacks = self.parse_callbacks;
-
-        // Add any extra arguments from the environment to the clang command line.
-        state.clang_args.extend(get_extra_clang_args());
-
-        // Transform input headers to arguments on the clang command line.
-        state.input_header = self.options.input_headers.pop();
-        state.extra_input_headers =
-            std::mem::take(&mut self.options.input_headers);
-        state.clang_args.extend(
-            state
-                .extra_input_headers
-                .iter()
-                .flat_map(|header| ["-include".into(), header.to_string()]),
-        );
-
-        state.input_unsaved_files.extend(
-            self.options.input_header_contents.drain(..).map(
-                |(name, contents)| clang::UnsavedFile::new(&name, &contents),
-            ),
-        );
+    pub fn generate(self) -> Result<Bindings, BindgenError> {
+        let state = BindgenState::build(&self.options, self.parse_callbacks);
 
         Bindings::generate(state, self.options)
     }
@@ -2273,7 +2252,37 @@ struct BindgenState {
 impl ::std::panic::UnwindSafe for BindgenState {}
 
 impl BindgenState {
-    fn build(options: &BindgenOptions) -> Self {
+    fn build(
+        options: &BindgenOptions,
+        parse_callbacks: Option<Box<dyn callbacks::ParseCallbacks>>,
+    ) -> Self {
+        let mut clang_args = options.clang_args.clone();
+
+        // Add any extra arguments from the environment to the clang command line.
+        clang_args.extend(get_extra_clang_args());
+
+        // Transform input headers to arguments on the clang command line.
+        let (input_header, extra_input_headers) =
+            if let Some((input_header, extra_input_headers)) =
+                options.input_headers.split_last()
+            {
+                (Some(input_header.clone()), extra_input_headers.to_vec())
+            } else {
+                Default::default()
+            };
+
+        clang_args.extend(
+            extra_input_headers
+                .iter()
+                .flat_map(|header| ["-include".into(), header.to_string()]),
+        );
+
+        let input_unsaved_files = options
+            .input_header_contents
+            .iter()
+            .map(|(name, contents)| clang::UnsavedFile::new(&name, &contents))
+            .collect();
+
         Self {
             allowlisted_vars: RegexSet::new(
                 options.allowlisted_vars.clone(),
@@ -2375,11 +2384,11 @@ impl BindgenState {
                 options.must_use_types.clone(),
                 options.record_matches,
             ),
-            clang_args: options.clang_args.clone(),
-            input_header: Default::default(),
-            extra_input_headers: Default::default(),
-            input_unsaved_files: Default::default(),
-            parse_callbacks: Default::default(),
+            clang_args,
+            input_header,
+            extra_input_headers,
+            input_unsaved_files,
+            parse_callbacks,
         }
     }
 }