c2rust Translation Failure with Enums in Compound Literals

[Yeaseen]

Description

When translating C code that initializes a struct's integer field from an enum using memcpy with a compound literal, c2rust fails, indicating potential unimplemented handling or a bug in translating such memory operations.

Source C code

#include <stdio.h>
#include <string.h> 
typedef enum {
    b=2
} a;

typedef struct {
    int data; 
} d_struct;

d_struct d;
int main() {
    // Initialize d with the value of `b` using compound literal and memcpy
    memcpy(&d.data, &((a){b}), sizeof(a));
    printf("Stored enum value: %d\n", d.data);
    return 0; }

Output by GCC and Clang

Stored enum value: 2

godbolt view

Observed Behavior: Transpilation Failure with the following error message

$ c2rust-transpile compile_commands.json -e -o transpiled_code --binary runner
Transpiling runner.c
error: Failed to translate main: Init list not implemented for Enum(CDeclId(1131))

I think this is related to memcpy as the following alternative for memcpy is correctly handled by c2rust

#include <stdio.h>
typedef enum {
    b=2
} a;

typedef struct {
    int data; 
} d_struct;

d_struct d;

int main() {
    a tmp = b;  
    *(int*)&d.data = tmp;
    printf("Stored enum value: %d\n", d.data);
    return 0; }

[fw-immunant]

This is not an issue with memcpy but with translation of enums in compound literals; the below code is a minimal reproducer:

typedef enum {
    b=2
} a;

int main() {
    (a){b};
    return 0;
}

[fw-immunant]

This seems to resolve the error:

diff --git a/c2rust-transpile/src/translator/literals.rs b/c2rust-transpile/src/translator/literals.rs
index d8eb64db6..861bb1467 100644
--- a/c2rust-transpile/src/translator/literals.rs
+++ b/c2rust-transpile/src/translator/literals.rs
@@ -246,6 +246,10 @@ impl<'c> Translation<'c> {
                 let id = ids.first().unwrap();
                 self.convert_expr(ctx.used(), *id)
             }
+            CTypeKind::Enum(_) => {
+                let id = ids.first().unwrap();
+                self.convert_expr(ctx.used(), *id)
+            }
             CTypeKind::Vector(CQualTypeId { ctype, .. }, len) => {
                 self.vector_list_initializer(ctx, ids, ctype, len)
             }

[Yeaseen]

Thank you for your response, @fw-immunant
I updated the title.

Should I give it a try and create a PR for this?

[kkysen]

Should I give it a try and create a PR for this?

Yeah, that would be great! Thanks!