Indexing an Optional slice would crash in codegen #1636.

releasenotes.md

@@ -17,6 +17,7 @@
 - Fix issue with resolved try-unwrap in defer.
 - Fix issue with overloaded subscript and ++/--.
 - Fix issue with properties in different targets not being respected #1633.
+- Indexing an Optional slice would crash in codegen #1636.
 
 ### Stdlib changes
 - Add `io::MultiReader`, `io::MultiWriter`, and `io::TeeReader` structs.

src/compiler/llvm_codegen_expr.c

@@ -5399,18 +5399,19 @@ void llvm_emit_slice_len(GenContext *c, BEValue *slice, BEValue *len)
 	llvm_value_set_address(len, len_addr, type_usz, alignment);
 }
 
-void llvm_emit_slice_pointer(GenContext *context, BEValue *slice, BEValue *pointer)
+void llvm_emit_slice_pointer(GenContext *c, BEValue *slice, BEValue *pointer)
 {
 	ASSERT0(slice->type->type_kind == TYPE_SLICE);
 	Type *ptr_type = type_get_ptr(slice->type->array.base);
+	llvm_value_fold_optional(c, slice);
 	if (slice->kind == BE_ADDRESS)
 	{
 		AlignSize alignment;
-		LLVMValueRef ptr = llvm_emit_struct_gep_raw(context, slice->value, llvm_get_type(context, slice->type), 0, slice->alignment, &alignment);
+		LLVMValueRef ptr = llvm_emit_struct_gep_raw(c, slice->value, llvm_get_type(c, slice->type), 0, slice->alignment, &alignment);
 		llvm_value_set_address(pointer, ptr, ptr_type, alignment);
 		return;
 	}
-	LLVMValueRef ptr = llvm_emit_extract_value(context, slice->value, 0);
+	LLVMValueRef ptr = llvm_emit_extract_value(c, slice->value, 0);
 	llvm_value_set(pointer, ptr, ptr_type);
 }
 

src/compiler/llvm_codegen_internal.h

@@ -529,7 +529,7 @@ LLVMValueRef llvm_emit_expect_raw(GenContext *c, LLVMValueRef expect_true);
 LLVMValueRef llvm_emit_expect_false(GenContext *c, BEValue *expect_false);
 void llvm_emit_any_from_value(GenContext *c, BEValue *value, Type *type);
 void llvm_emit_slice_len(GenContext *c, BEValue *slice, BEValue *len);
-void llvm_emit_slice_pointer(GenContext *context, BEValue *slice, BEValue *pointer);
+void llvm_emit_slice_pointer(GenContext *c, BEValue *slice, BEValue *pointer);
 void llvm_emit_compound_stmt(GenContext *c, Ast *ast);
 LLVMValueRef llvm_emit_const_bitstruct(GenContext *c, ConstInitializer *initializer);
 void llvm_emit_function_body(GenContext *context, Decl *decl);

test/test_suite/slices/slice_optional.c3t

@@ -0,0 +1,41 @@
+// #target: macos-x64
+module test;
+fn void main() {
+  int[]! a = {1, 2};
+  int! b = a[0];
+}
+
+/* #expect: test.ll
+
+define void @test.main() #0 {
+entry:
+  %a = alloca %"int[]", align 8
+  %a.f = alloca i64, align 8
+  %literal = alloca [2 x i32], align 4
+  %b = alloca i32, align 4
+  %b.f = alloca i64, align 8
+  call void @llvm.memcpy.p0.p0.i32(ptr align 4 %literal, ptr align 4 @.__const, i32 8, i1 false)
+  %0 = insertvalue %"int[]" undef, ptr %literal, 0
+  %1 = insertvalue %"int[]" %0, i64 2, 1
+  store %"int[]" %1, ptr %a, align 8
+  store i64 0, ptr %a.f, align 8
+  %optval = load i64, ptr %a.f, align 8
+  %not_err = icmp eq i64 %optval, 0
+  %2 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
+  br i1 %2, label %after_check, label %assign_optional
+
+assign_optional:                                  ; preds = %entry
+  store i64 %optval, ptr %b.f, align 8
+  br label %after_assign
+
+after_check:                                      ; preds = %entry
+  %3 = load ptr, ptr %a, align 8
+  %4 = load i32, ptr %3, align 4
+  store i32 %4, ptr %b, align 4
+  store i64 0, ptr %b.f, align 8
+  br label %after_assign
+
+after_assign:                                     ; preds = %after_check, %assign_optional
+  ret void
+}
+