transpile: fix previously ignored enum usage in compound literals (…

…#1185)

* Fixes #1168.
   
### Modification:
- Suggested changes mentioned in #1168 were added in the
`c2rust-transpile/src/translator/literals.rs` file
- Added a relevant C program in `tests/enums/src/enum_compound.c` file
- Modified `tests/enums/src/test_enums.rs` file to check the correct
outputs

### Testing

The added test case specifically checks for the correct assignment of
enum values in buffer initialization using compound literals. This test
has been integrated into the existing test suite and passed
successfully, confirming the fix.

c2rust-transpile/src/translator/literals.rs

@@ -254,6 +254,10 @@ 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)
             }

tests/enums/src/enum_compound.c

@@ -0,0 +1,13 @@
+
+typedef enum {
+    B = 2
+} a;
+
+void entry6(const unsigned buffer_size, int buffer[]) {
+  if (buffer_size < 1) {
+    return; 
+  }
+
+  // Using a compound literal with enum to assign the value
+  buffer[0] = (a) { B };
+}

tests/enums/src/test_enums.rs

@@ -7,6 +7,7 @@ use crate::non_canonical_enum_def::{
     hrtimer_restart, rust_abc, HRTIMER_NORESTART, HRTIMER_RESTART,
 };
 use crate::top_enum::{rust_entry4, E as otherE};
+use crate::enum_compound::rust_entry6;
 
 use libc::{c_int, c_uint};
 
@@ -21,13 +22,16 @@ extern "C" {
     fn entry4(_: c_uint, _: *mut c_int);
 
     fn entry5(_: c_uint, _: *mut c_int);
+
+    fn entry6(_: c_uint, _: *mut c_int);
 }
 
 const BUFFER_SIZE: usize = 10;
 const BUFFER_SIZE2: usize = 7;
 const BUFFER_SIZE3: usize = 4;
 const BUFFER_SIZE4: usize = 1;
 const BUFFER_SIZE5: usize = 6;
+const BUFFER_SIZE6: usize = 1;
 
 pub fn test_variants() {
     assert_eq!(A as u32, 0);
@@ -103,3 +107,17 @@ pub fn test_buffer5() {
     assert_eq!(buffer, rust_buffer);
     assert_eq!(buffer, expected_buffer);
 }
+
+pub fn test_buffer6() {
+    let mut buffer = [0; BUFFER_SIZE6];
+    let mut rust_buffer = [0; BUFFER_SIZE6];
+    let expected_buffer = [2];
+
+    unsafe {
+        entry6(BUFFER_SIZE6 as u32, buffer.as_mut_ptr());
+        rust_entry6(BUFFER_SIZE6 as u32, rust_buffer.as_mut_ptr());
+    }
+
+    assert_eq!(buffer, rust_buffer);
+    assert_eq!(buffer, expected_buffer);
+}