Auto merge of #1272 - tmfink:issue-1198, r=emilio

Declare precedence on enum types

Fixes issue #1198 where an enum matches the pattern for multiple enum types, such as constified module enum AND rustified enum.

Documents precedence in `Builder` doc comment.

2 files changed, 21 insertions, 2 deletions

diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
index a6ab3997..cf1a4f3b 100644
--- a/src/codegen/mod.rs
+++ b/src/codegen/mod.rs
@@ -2477,12 +2477,14 @@ impl CodeGenerator for Enum {
             }
         };
 
+        // ModuleConsts has higher precedence before Rust in order to avoid problems with
+        // overlapping match patterns
         let variation = if self.is_bitfield(ctx, item) {
             EnumVariation::Bitfield
-        } else if self.is_rustified_enum(ctx, item) {
-            EnumVariation::Rust
         } else if self.is_constified_enum_module(ctx, item) {
             EnumVariation::ModuleConsts
+        } else if self.is_rustified_enum(ctx, item) {
+            EnumVariation::Rust
         } else {
             // We generate consts by default
             EnumVariation::Consts
diff --git a/src/lib.rs b/src/lib.rs
index 6346ff80..36378316 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -155,6 +155,23 @@ impl Default for CodegenConfig {
 /// // Write the generated bindings to an output file.
 /// bindings.write_to_file("path/to/output.rs")?;
 /// ```
+///
+/// # Enums
+///
+/// Bindgen can map C/C++ enums into Rust in different ways. The way bindgen maps enums depends on
+/// the pattern passed to several methods:
+///
+/// 1. [`bitfield_enum()`](#method.bitfield_enum)
+/// 2. [`constified_enum_module()`](#method.constified_enum_module)
+/// 3. [`rustified_enum()`](#method.rustified_enum)
+///
+/// For each C enum, bindgen tries to match the pattern in the following order:
+///
+/// 1. Bitfield enum
+/// 2. Constified enum module
+/// 3. Rustified enum
+///
+/// If none of the above patterns match, then bindgen will generate a set of Rust constants.
 #[derive(Debug, Default)]
 pub struct Builder {
     options: BindgenOptions,