From 475816251b82bce68169195aacba04df649b8b36 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Fri, 12 Dec 2025 20:35:11 +0100
Subject: [PATCH] - Strings assigned to longer arrays would crash codegen, e.g.
 `char[10] x = "abcd`.

---
 releasenotes.md                               |  1 +
 src/compiler/llvm_codegen_expr.c              |  7 ++++---
 .../constants/array_zero_string_long.c3t      | 21 +++++++++++++++++++
 3 files changed, 26 insertions(+), 3 deletions(-)
 create mode 100644 test/test_suite/constants/array_zero_string_long.c3t

diff --git a/releasenotes.md b/releasenotes.md
index c4c6d3b0a..ecc984f38 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -15,6 +15,7 @@
 - Ignore const null check on deref in `$defined` and `$sizeof` #2633.
 - Subscripting of constant slices would sometimes be considered non-constant #2635.
 - Compiler crash when concatenating structs and arrays to an untyped list.
+- Strings assigned to longer arrays would crash codegen, e.g. `char[10] x = "abcd`.
 
 ### Stdlib changes
 - Add `ThreadPool` join function to wait for all threads to finish in the pool without destroying the threads.
diff --git a/src/compiler/llvm_codegen_expr.c b/src/compiler/llvm_codegen_expr.c
index fe7210f95..6064ef03f 100644
--- a/src/compiler/llvm_codegen_expr.c
+++ b/src/compiler/llvm_codegen_expr.c
@@ -4821,9 +4821,6 @@ static void llvm_emit_const_expr(GenContext *c, BEValue *be_value, Expr *expr)
 			ArraySize size = expr->const_expr.bytes.len;
 			size++;
 			if (is_array && type->array.len > size) size = type->array.len;
-			LLVMValueRef global_name = llvm_add_global_raw(c, is_bytes ? ".bytes" : ".str", LLVMArrayType(llvm_get_type(c, type_char), size), 1);
-			llvm_set_private_declaration(global_name);
-			LLVMSetGlobalConstant(global_name, 1);
 			LLVMValueRef data = llvm_get_zstring(c, expr->const_expr.bytes.ptr, expr->const_expr.bytes.len);
 			LLVMValueRef trailing_zeros = NULL;
 			if (size > len + 1)
@@ -4835,6 +4832,10 @@ static void llvm_emit_const_expr(GenContext *c, BEValue *be_value, Expr *expr)
 				LLVMValueRef values[2] = { data, trailing_zeros };
 				data = llvm_get_packed_struct(c, values, 2);
 			}
+			LLVMValueRef global_name = llvm_add_global_raw(c, is_bytes ? ".bytes" : ".str", LLVMTypeOf(data), 1);
+			llvm_set_private_declaration(global_name);
+			LLVMSetGlobalConstant(global_name, 1);
+
 			LLVMSetInitializer(global_name, data);
 			if (is_array)
 			{
diff --git a/test/test_suite/constants/array_zero_string_long.c3t b/test/test_suite/constants/array_zero_string_long.c3t
new file mode 100644
index 000000000..187486f90
--- /dev/null
+++ b/test/test_suite/constants/array_zero_string_long.c3t
@@ -0,0 +1,21 @@
+// #target: macos-x64
+
+module test;
+import std;
+
+fn int main()
+{
+	char[10] x = "abcd";
+	return 0;
+}
+
+/* #expect: test.ll
+
+@.str = private unnamed_addr constant <{ [5 x i8], [5 x i8] }> <{ [5 x i8] c"abcd\00", [5 x i8] zeroinitializer }>, align 1
+
+define i32 @main() #0 {
+entry:
+  %x = alloca [10 x i8], align 1
+  call void @llvm.memcpy.p0.p0.i32(ptr align 1 %x, ptr align 1 @.str, i32 10, i1 false)
+  ret i32 0
+}