Auto merge of #220 - jcdyer:enum_value_signed, r=emilio

Wrap enum_val_signed in an Option.

Also reorganize calling code to avoid duplicate checking of cursor type.

Fixes #127

Author: bors-servo

src/clang.rs

@@ -349,11 +349,15 @@ impl Cursor {
 
     /// Get the signed constant value for this cursor's enum variant referent.
     ///
-    /// Returns `LLONG_MIN` if the cursor's referent is not an enum variant,
-    /// which is also a valid enum value, so callers should check the cursor
-    /// kind before calling this method (see issue #127).
-    pub fn enum_val_signed(&self) -> i64 {
-        unsafe { clang_getEnumConstantDeclValue(self.x) as i64 }
+    /// Returns None if the cursor's referent is not an enum variant.
+    pub fn enum_val_signed(&self) -> Option<i64> {
+        unsafe {
+            if self.kind() == CXCursor_EnumConstantDecl {
+                Some(clang_getEnumConstantDeclValue(self.x) as i64)
+            } else {
+                None
+            }
+        }
     }
 
     /// Get the unsigned constant value for this cursor's enum variant referent.

src/ir/enum_ty.rs

@@ -72,18 +72,19 @@ impl Enum {
 
         declaration.visit(|cursor| {
             if cursor.kind() == CXCursor_EnumConstantDecl {
-                let name = cursor.spelling();
-                let comment = cursor.raw_comment();
-                let val = if is_signed {
-                    EnumVariantValue::Signed(cursor.enum_val_signed())
+                let value = if is_signed {
+                    cursor.enum_val_signed().map(EnumVariantValue::Signed)
                 } else {
-                    EnumVariantValue::Unsigned(cursor.enum_val_unsigned())
+                    Some(EnumVariantValue::Unsigned(cursor.enum_val_unsigned()))
                 };
-                variants.push(EnumVariant::new(name, comment, val));
+                if let Some(val) = value {
+                    let name = cursor.spelling();
+                    let comment = cursor.raw_comment();
+                    variants.push(EnumVariant::new(name, comment, val));
+                }
             }
             CXChildVisit_Continue
         });
-
         Ok(Enum::new(repr, variants))
     }
 }