Add option to generate safe and unsafe conversions for rustified enums

Author: jbaublitz

Diff for: bindgen-integration/build.rs

@@ -192,6 +192,8 @@ fn setup_macro_test() {
         .enable_cxx_namespaces()
         .default_enum_style(EnumVariation::Rust {
             non_exhaustive: false,
+            safe_conversion: false,
+            unsafe_conversion: false,
         })
         .raw_line("pub use self::root::*;")
         .raw_line("extern { fn my_prefixed_function_to_remove(i: i32); }")

Diff for: bindgen-tests/tests/expectations/tests/issue-2646.rs

@@ -0,0 +1,30 @@
+// bindgen-flags: --rustified-enum 'Plain.*' --rustified-enum 'TryFromRaw.*=try_from_raw' --rustified-enum='FromRawUnchecked.*=from_raw_unchecked' --rustified-enum='Both.*=try_from_raw,from_raw_unchecked' --rustified-enum 'NonExhaustive.*=non_exhaustive'
+
+enum Plain {
+    Plain1,
+    Plain2,
+    Plain3
+};
+
+enum TryFromRaw {
+    TFR1 = -1,
+    TFR2 = 5,
+    TFR3
+};
+
+enum FromRawUnchecked {
+    FRU1 = 6,
+    FRU2 = 10,
+    FRU3 = 11,
+};
+
+enum Both {
+    Both1,
+    Both2 = -1,
+    Both3,
+};
+
+enum NonExhaustive {
+    Ex1,
+    Ex2,
+};