From e3405fdf36717bd4b01bcab64c1747d148c9a78d Mon Sep 17 00:00:00 2001
From: Folkert de Vries <folkert@folkertdev.nl>
Date: Thu, 28 Nov 2024 00:02:26 +0100
Subject: [PATCH] emit zeroed arrays as `[0; N]`

an array like `int x[16] = {}` was emitted as `[0, 0, 0, 0, ...]`,
but is not emitted as `[0; 16]`.
---
 c2rust-transpile/src/translator/literals.rs | 8 ++++++++
 tests/arrays/src/arrays.c                   | 4 +++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/c2rust-transpile/src/translator/literals.rs b/c2rust-transpile/src/translator/literals.rs
index d8eb64db64..ba643c1c7d 100644
--- a/c2rust-transpile/src/translator/literals.rs
+++ b/c2rust-transpile/src/translator/literals.rs
@@ -190,6 +190,14 @@ impl<'c> Translation<'c> {
                 if is_string {
                     let v = ids.first().unwrap();
                     self.convert_expr(ctx.used(), *v)
+                } else if ids.len() == 0 && ty.is_integral_type() || ty.is_floating_type() {
+                    // this was likely a C array of the form `int x[16] = {}`,
+                    // we'll emit that as [0; 16].
+                    let len = mk().lit_expr(mk().int_unsuffixed_lit(n as u128));
+                    self.implicit_default_expr(ty, ctx.is_static)?
+                        .and_then(|default_value| {
+                            Ok(WithStmts::new_val(mk().repeat_expr(default_value, len)))
+                        })
                 } else {
                     Ok(ids
                         .iter()
diff --git a/tests/arrays/src/arrays.c b/tests/arrays/src/arrays.c
index 9a5f3c9f6f..79868f7bfe 100644
--- a/tests/arrays/src/arrays.c
+++ b/tests/arrays/src/arrays.c
@@ -6,9 +6,11 @@ static char *foo = "mystring";
 void entry(const unsigned buffer_size, int buffer[const])
 {
     int arr[1][1] = { 1 };
-
     arr[0][0] += 9;
 
+    int arr2[16] = {};
+    arr2[15] += 9;
+
     int i = 0;
 
     char abc[] = "abc";