Auto merge of #150 - malfunc:master, r=emilio,fitzgen

fix: clang::Cursor::num_args should return Option<u32> #132

Hi, tried to fix the issue mentioned. Not sure, if changing fn args makes sense (the err message probably doesn't...). cargo test --features llvm_stable was succesful.
- changed output of fn num_args to option<u32>
- changed fn args to handle option<u32> instead of usize

1 files changed, 8 insertions, 3 deletions

diff --git a/src/clang.rs b/src/clang.rs
index fa4eb01b..e3e0f313 100755
--- a/src/clang.rs
+++ b/src/clang.rs
@@ -393,7 +393,7 @@ impl Cursor {
     /// parameters.
     pub fn args(&self) -> Vec<Cursor> {
         unsafe {
-            let num = self.num_args() as usize;
+            let num = self.num_args().expect("expected value, got none") as u32;
             let mut args = vec![];
             for i in 0..num {
                 args.push(Cursor { x: clang_Cursor_getArgument(self.x, i as c_uint) });
@@ -415,9 +415,14 @@ impl Cursor {
     ///
     /// Returns -1 if the cursor's referent is not a function/method call or
     /// declaration.
-    pub fn num_args(&self) -> i32 {
+    pub fn num_args(&self) -> Result<u32, ()> {
         unsafe {
-            clang_Cursor_getNumArguments(self.x)
+            let w = clang_Cursor_getNumArguments(self.x);
+            if w == -1 {
+                Err(())
+            } else {
+                Ok(w as u32)
+            }
         }
     }