Add Inc and Dec traits for enums (#153)

This implements PostfixInc, PrefixInc, PostfixDec, PrefixDec for all
user defined enum types.

Instead of generatic more than 30 lines of trait implementations per
user-defined enum, I declared a macro in libcc2rs that enums call in
order to take care of the actual trait implementation.

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -2892,6 +2892,7 @@ bool Converter::VisitEnumDecl(clang::EnumDecl *decl) {
   StrCat("}");
 
   AddFromImpl(decl);
+  AddIncDecImpls(decl);
   return false;
 }
 
@@ -2913,6 +2914,10 @@ void Converter::AddFromImpl(clang::EnumDecl *decl) {
   StrCat(std::format("_ => panic!(\"invalid {} value: {{}}\", n),", name));
 }
 
+void Converter::AddIncDecImpls(clang::EnumDecl *decl) {
+  StrCat(std::format("libcc2rs::impl_enum_inc_dec!({});", GetRecordName(decl)));
+}
+
 bool Converter::VisitCXXDefaultArgExpr(clang::CXXDefaultArgExpr *expr) {
   if (expr->getType()->isPointerType()) {
     StrCat(keyword_default_);

cpp2rust/converter/converter.h

@@ -315,6 +315,8 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
 
   virtual void AddFromImpl(clang::EnumDecl *decl);
 
+  virtual void AddIncDecImpls(clang::EnumDecl *decl);
+
   virtual bool VisitCXXDefaultArgExpr(clang::CXXDefaultArgExpr *expr);
 
   virtual bool VisitLambdaExpr(clang::LambdaExpr *expr);

libcc2rs/src/inc.rs

@@ -124,6 +124,38 @@ impl<T> UnsafePrefixInc for *mut T {
     }
 }
 
+#[macro_export]
+macro_rules! impl_enum_inc_dec {
+    ($t:ty) => {
+        impl PostfixInc for $t {
+            fn postfix_inc(&mut self) -> Self {
+                let copy = *self;
+                *self = <$t>::from(*self as i32 + 1);
+                copy
+            }
+        }
+        impl PrefixInc for $t {
+            fn prefix_inc(&mut self) -> Self {
+                *self = <$t>::from(*self as i32 + 1);
+                *self
+            }
+        }
+        impl PostfixDec for $t {
+            fn postfix_dec(&mut self) -> Self {
+                let copy = *self;
+                *self = <$t>::from(*self as i32 - 1);
+                copy
+            }
+        }
+        impl PrefixDec for $t {
+            fn prefix_dec(&mut self) -> Self {
+                *self = <$t>::from(*self as i32 - 1);
+                *self
+            }
+        }
+    };
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

tests/ub/enum_out_of_range_increment.c

@@ -0,0 +1,9 @@
+// panic
+
+enum color { RED, GREEN, BLUE };
+
+int main() {
+  enum color c = BLUE;
+  c++;
+  return c == RED ? 0 : 1;
+}

tests/ub/out/refcount/enum_out_of_range_cast.rs

@@ -23,6 +23,7 @@ impl From<i32> for Color {
         }
     }
 }
+libcc2rs::impl_enum_inc_dec!(Color);
 pub fn main() {
     std::process::exit(main_0());
 }

tests/ub/out/refcount/enum_out_of_range_increment.rs

@@ -0,0 +1,38 @@
+extern crate libcc2rs;
+use libcc2rs::*;
+use std::cell::RefCell;
+use std::collections::BTreeMap;
+use std::io::prelude::*;
+use std::io::{Read, Seek, Write};
+use std::os::fd::AsFd;
+use std::rc::{Rc, Weak};
+#[derive(Clone, Copy, PartialEq, Debug, Default)]
+enum color {
+    #[default]
+    RED = 0,
+    GREEN = 1,
+    BLUE = 2,
+}
+impl From<i32> for color {
+    fn from(n: i32) -> color {
+        match n {
+            0 => color::RED,
+            1 => color::GREEN,
+            2 => color::BLUE,
+            _ => panic!("invalid color value: {}", n),
+        }
+    }
+}
+libcc2rs::impl_enum_inc_dec!(color);
+pub fn main() {
+    std::process::exit(main_0());
+}
+fn main_0() -> i32 {
+    let c: Value<color> = Rc::new(RefCell::new(color::BLUE));
+    (*c.borrow_mut()).postfix_inc();
+    return if (((((*c.borrow()) as u32) == ((color::RED as i32) as u32)) as i32) != 0) {
+        0
+    } else {
+        1
+    };
+}

tests/ub/out/unsafe/enum_out_of_range_cast.rs

@@ -23,6 +23,7 @@ impl From<i32> for Color {
         }
     }
 }
+libcc2rs::impl_enum_inc_dec!(Color);
 pub fn main() {
     unsafe {
         std::process::exit(main_0() as i32);

tests/ub/out/unsafe/enum_out_of_range_increment.rs

@@ -0,0 +1,40 @@
+extern crate libc;
+use libc::*;
+extern crate libcc2rs;
+use libcc2rs::*;
+use std::collections::BTreeMap;
+use std::io::{Read, Seek, Write};
+use std::os::fd::{AsFd, FromRawFd, IntoRawFd};
+use std::rc::Rc;
+#[derive(Clone, Copy, PartialEq, Debug, Default)]
+enum color {
+    #[default]
+    RED = 0,
+    GREEN = 1,
+    BLUE = 2,
+}
+impl From<i32> for color {
+    fn from(n: i32) -> color {
+        match n {
+            0 => color::RED,
+            1 => color::GREEN,
+            2 => color::BLUE,
+            _ => panic!("invalid color value: {}", n),
+        }
+    }
+}
+libcc2rs::impl_enum_inc_dec!(color);
+pub fn main() {
+    unsafe {
+        std::process::exit(main_0() as i32);
+    }
+}
+unsafe fn main_0() -> i32 {
+    let mut c: color = color::BLUE;
+    c.postfix_inc();
+    return if ((((c as u32) == ((color::RED as i32) as u32)) as i32) != 0) {
+        0
+    } else {
+        1
+    };
+}

tests/unit/enum_increment.c

@@ -0,0 +1,18 @@
+#include <assert.h>
+
+enum color { RED, GREEN, BLUE, COLOR_LAST };
+
+int main() {
+  int count = 0;
+  for (enum color c = RED; c < COLOR_LAST; c++) {
+    count++;
+  }
+  assert(count == 3);
+
+  enum color c = RED;
+  assert(c++ == RED);
+  assert(++c == BLUE);
+  assert(c-- == BLUE);
+  assert(--c == RED);
+  return 0;
+}

tests/unit/out/refcount/anonymous_enum.rs

@@ -21,6 +21,7 @@ impl From<i32> for anon_enum_3 {
         }
     }
 }
+libcc2rs::impl_enum_inc_dec!(anon_enum_3);
 #[derive(Clone, Copy, PartialEq, Debug, Default)]
 enum anon_enum_11 {
     #[default]
@@ -36,6 +37,7 @@ impl From<i32> for anon_enum_11 {
         }
     }
 }
+libcc2rs::impl_enum_inc_dec!(anon_enum_11);
 #[derive(Default)]
 pub struct S {
     pub a: Value<i32>,
@@ -73,6 +75,7 @@ impl From<i32> for TdEnum {
         }
     }
 }
+libcc2rs::impl_enum_inc_dec!(TdEnum);
 #[derive(Clone, Copy, PartialEq, Debug, Default)]
 enum anon_enum_24 {
     #[default]
@@ -88,6 +91,7 @@ impl From<i32> for anon_enum_24 {
         }
     }
 }
+libcc2rs::impl_enum_inc_dec!(anon_enum_24);
 #[derive(Default)]
 pub struct WithAnonField {
     pub a: Value<i32>,
@@ -121,7 +125,8 @@ fn main_0() -> i32 {
                 _ => panic!("invalid anon_enum_31 value: {}", n),
             }
         }
-    };
+    }
+    libcc2rs::impl_enum_inc_dec!(anon_enum_31);
     assert!(((anon_enum_3::FIRST_A as i32) != (anon_enum_3::FIRST_B as i32)));
     assert!(((anon_enum_11::SECOND_A as i32) != (anon_enum_11::SECOND_B as i32)));
     assert!(((anon_enum_31::THIRD_A as i32) != (anon_enum_31::THIRD_B as i32)));