From 8785c2c46fe90c2dc9a45fe6dd4a18451a7f345a Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sat, 11 Jan 2025 22:42:33 +0100
Subject: [PATCH] Assert when partially initializing a constant struct
 containing a slice #1812.

---
 releasenotes.md                               |  1 +
 src/compiler/llvm_codegen.c                   | 11 +++---
 test/test_suite/struct/const_slice_struct.c3t | 37 +++++++++++++++++++
 3 files changed, 43 insertions(+), 6 deletions(-)
 create mode 100644 test/test_suite/struct/const_slice_struct.c3t

diff --git a/releasenotes.md b/releasenotes.md
index eef24f4f0..60cc974c1 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -76,6 +76,7 @@
 - Fix bug preventing compile time slices from being iterated over with `$foreach`.
 - Fix bug with defer assignment in macro #1807.
 - Fix regression with swizzle references for vectors #1810.
+- Assert when partially initializing a constant struct containing a slice #1812.
 
 ### Stdlib changes
 - Increase BitWriter.write_bits limit up to 32 bits.
diff --git a/src/compiler/llvm_codegen.c b/src/compiler/llvm_codegen.c
index 3341ebb48..e822ae464 100644
--- a/src/compiler/llvm_codegen.c
+++ b/src/compiler/llvm_codegen.c
@@ -233,21 +233,20 @@ LLVMValueRef llvm_emit_const_initializer(GenContext *c, ConstInitializer *const_
 	switch (const_init->kind)
 	{
 		case CONST_INIT_ZERO:
-			ASSERT0(const_init->type->type_kind != TYPE_SLICE);
 			return llvm_get_zero(c, const_init->type);
 		case CONST_INIT_ARRAY_VALUE:
 			UNREACHABLE
 		case CONST_INIT_ARRAY_FULL:
 		{
-			ASSERT0(const_init->type->type_kind != TYPE_SLICE);
+			ASSERT(const_init, const_init->type->type_kind != TYPE_SLICE);
 			bool was_modified = false;
 			Type *array_type = const_init->type;
 			Type *element_type = array_type->array.base;
 			LLVMTypeRef element_type_llvm = llvm_get_type(c, element_type);
 			ConstInitializer **elements = const_init->init_array_full;
-			ASSERT0(array_type->type_kind == TYPE_ARRAY || array_type->type_kind == TYPE_VECTOR);
+			ASSERT(const_init, array_type->type_kind == TYPE_ARRAY || array_type->type_kind == TYPE_VECTOR);
 			ArraySize size = array_type->array.len;
-			ASSERT0(size > 0);
+			ASSERT(const_init, size > 0);
 			LLVMValueRef *parts = VECNEW(LLVMValueRef, size);
 			for (ArrayIndex i = 0; i < (ArrayIndex)size; i++)
 			{
@@ -268,14 +267,14 @@ LLVMValueRef llvm_emit_const_initializer(GenContext *c, ConstInitializer *const_
 
 		case CONST_INIT_ARRAY:
 		{
-			ASSERT0(const_init->type->type_kind != TYPE_SLICE);
+			ASSERT(const_init, const_init->type->type_kind != TYPE_SLICE);
 			bool was_modified = false;
 			Type *array_type = const_init->type;
 			Type *element_type = array_type->array.base;
 			LLVMTypeRef element_type_llvm = llvm_get_type(c, element_type);
 			AlignSize expected_align = llvm_abi_alignment(c, element_type_llvm);
 			ConstInitializer **elements = const_init->init_array.elements;
-			ASSERT0(vec_size(elements) > 0 && "Array should always have gotten at least one element.");
+			ASSERT(const_init, vec_size(elements) > 0 && "Array should always have gotten at least one element.");
 			ArrayIndex current_index = 0;
 			unsigned alignment = 0;
 			LLVMValueRef *parts = NULL;
diff --git a/test/test_suite/struct/const_slice_struct.c3t b/test/test_suite/struct/const_slice_struct.c3t
new file mode 100644
index 000000000..837488e2e
--- /dev/null
+++ b/test/test_suite/struct/const_slice_struct.c3t
@@ -0,0 +1,37 @@
+// #target: macos-x64
+module test;
+// Issue #1812
+struct Foo
+{
+  float a;
+  String b;
+}
+
+struct Bar
+{
+	float a;
+	int[] b;
+}
+const Foo FOO = {.a = 1};
+const Bar FOO2 = {.a = 1, .b = { 1, 3 } };
+
+fn int main()
+{
+  Foo asdf = FOO;
+  Bar foek = FOO2;
+  return 0;
+}
+
+/* #expect: test.ll
+
+@test.FOO = local_unnamed_addr constant %Foo { float 1.000000e+00, %"char[]" zeroinitializer }, align 8
+@.__const_slice = private unnamed_addr global [2 x i32] [i32 1, i32 3], align 4
+@test.FOO2 = local_unnamed_addr constant %Bar { float 1.000000e+00, %"int[]" { ptr @.__const_slice, i64 2 } }, align 8
+
+entry:
+  %asdf = alloca %Foo, align 8
+  %foek = alloca %Bar, align 8
+  call void @llvm.memcpy.p0.p0.i32(ptr align 8 %asdf, ptr align 8 @test.FOO, i32 24, i1 false)
+  call void @llvm.memcpy.p0.p0.i32(ptr align 8 %foek, ptr align 8 @test.FOO2, i32 24, i1 false)
+  ret i32 0
+}