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.

Author: bors-servo

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

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,

tests/expectations/tests/issue-1198-alias-rust-const-mod-enum.rs

@@ -0,0 +1,16 @@
+/* automatically generated by rust-bindgen */
+
+#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+
+pub mod MyDupeEnum {
+    pub type Type = u32;
+    pub const A: Type = 0;
+    pub const A_alias: Type = 0;
+    pub const B: Type = 1;
+}
+pub mod MyOtherDupeEnum {
+    pub type Type = u32;
+    pub const C: Type = 0;
+    pub const C_alias: Type = 0;
+    pub const D: Type = 1;
+}

tests/expectations/tests/issue-1198-alias-rust-enum.rs

@@ -0,0 +1,18 @@
+/* automatically generated by rust-bindgen */
+
+#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+
+pub const MyDupeEnum_A_alias: MyDupeEnum = MyDupeEnum::A;
+#[repr(u32)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub enum MyDupeEnum {
+    A = 0,
+    B = 1,
+}
+pub const MyOtherDupeEnum_C_alias: MyOtherDupeEnum = MyOtherDupeEnum::C;
+#[repr(u32)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub enum MyOtherDupeEnum {
+    C = 0,
+    D = 1,
+}

tests/headers/issue-1198-alias-rust-const-mod-enum.h

@@ -0,0 +1,13 @@
+// bindgen-flags: --rustified-enum '.*' --constified-enum-module '.*'
+
+typedef enum MyDupeEnum {
+	A = 0,
+	A_alias = 0,
+	B,
+} MyDupeEnum;
+
+enum MyOtherDupeEnum {
+	C = 0,
+	C_alias = 0,
+	D,
+};

tests/headers/issue-1198-alias-rust-enum.h

@@ -0,0 +1,14 @@
+// bindgen-flags: --rustified-enum '.*'
+
+
+typedef enum MyDupeEnum {
+	A = 0,
+	A_alias = 0,
+	B,
+} MyDupeEnum;
+
+enum MyOtherDupeEnum {
+	C = 0,
+	C_alias = 0,
+	D,
+};