From 6454856fdbea107a51178200f91ba366808fb427 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Wed, 16 Apr 2025 23:19:28 +0200
Subject: [PATCH] String str = "" is now guaranteed to be null terminated.
 #2083

---
 releasenotes.md                               |  1 +
 src/compiler/llvm_codegen_expr.c              |  3 +-
 test/test_suite/bitstruct/bitstruct_be.c3t    |  6 +--
 .../test_suite/compile_time/concat_append.c3t |  3 +-
 .../compile_time/ct_forach_with_defer.c3t     | 41 ++++++++++++++++++-
 test/test_suite/compile_time/ct_memberof.c3t  | 32 ++++++++++++---
 test/test_suite/errors/error_regression_2.c3t | 17 +++-----
 test/test_suite/from_docs/examples_defer.c3t  |  6 +--
 .../struct/init_cont_struct_array_locally.c3t | 40 +++++++++++++++++-
 9 files changed, 123 insertions(+), 26 deletions(-)

diff --git a/releasenotes.md b/releasenotes.md
index bf80ee6f3..e1f9b46b1 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -13,6 +13,7 @@
 - Make aliases able to use `@deprecated`.
 - Refactored stdlib file organization.
 - Allow `@if` on locals.
+- String str = "" is now guaranteed to be null terminated. #2083
 
 ### Fixes
 - Trying to cast an enum to int and back caused the compiler to crash.
diff --git a/src/compiler/llvm_codegen_expr.c b/src/compiler/llvm_codegen_expr.c
index 9971017f7..9a688cac8 100644
--- a/src/compiler/llvm_codegen_expr.c
+++ b/src/compiler/llvm_codegen_expr.c
@@ -4701,7 +4701,8 @@ static void llvm_emit_const_expr(GenContext *c, BEValue *be_value, Expr *expr)
 			ArraySize len = expr->const_expr.bytes.len;
 			if (len == 0 && str_type->type_kind == TYPE_SLICE)
 			{
-				llvm_value_set(be_value, llvm_get_zero(c, expr->type), expr->type);
+				LLVMValueRef data[2] = { llvm_emit_zstring_named(c, "", ".emptystr"), llvm_get_zero(c, type_usz) };
+				llvm_value_set(be_value, llvm_get_struct_named(c->chars_type, data, 2), expr->type);
 				return;
 			}
 			ArraySize size = expr->const_expr.bytes.len;
diff --git a/test/test_suite/bitstruct/bitstruct_be.c3t b/test/test_suite/bitstruct/bitstruct_be.c3t
index 5e20ec6eb..4458f51b7 100644
--- a/test/test_suite/bitstruct/bitstruct_be.c3t
+++ b/test/test_suite/bitstruct/bitstruct_be.c3t
@@ -86,7 +86,7 @@ loop.body:                                        ; preds = %loop.cond
 
 loop.exit:                                        ; preds = %loop.cond
   %17 = call ptr @std.io.stdout()
-  %18 = call i64 @std.io.File.write(ptr %retparam5, ptr %17, ptr null, i64 0)
+  %18 = call i64 @std.io.File.write(ptr %retparam5, ptr %17, ptr @.emptystr, i64 0)
   %not_err = icmp eq i64 %18, 0
   %19 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
   br i1 %19, label %after_check, label %assign_optional
@@ -166,7 +166,7 @@ loop.body21:                                      ; preds = %loop.cond19
 
 loop.exit29:                                      ; preds = %loop.cond19
   %34 = call ptr @std.io.stdout()
-  %35 = call i64 @std.io.File.write(ptr %retparam33, ptr %34, ptr null, i64 0)
+  %35 = call i64 @std.io.File.write(ptr %retparam33, ptr %34, ptr @.emptystr, i64 0)
   %not_err34 = icmp eq i64 %35, 0
   %36 = call i1 @llvm.expect.i1(i1 %not_err34, i1 true)
   br i1 %36, label %after_check36, label %assign_optional35
@@ -276,7 +276,7 @@ loop.body67:                                      ; preds = %loop.cond65
 
 loop.exit75:                                      ; preds = %loop.cond65
   %73 = call ptr @std.io.stdout()
-  %74 = call i64 @std.io.File.write(ptr %retparam79, ptr %73, ptr null, i64 0)
+  %74 = call i64 @std.io.File.write(ptr %retparam79, ptr %73, ptr @.emptystr, i64 0)
   %not_err80 = icmp eq i64 %74, 0
   %75 = call i1 @llvm.expect.i1(i1 %not_err80, i1 true)
   br i1 %75, label %after_check82, label %assign_optional81
diff --git a/test/test_suite/compile_time/concat_append.c3t b/test/test_suite/compile_time/concat_append.c3t
index ccd583762..610213b5e 100644
--- a/test/test_suite/compile_time/concat_append.c3t
+++ b/test/test_suite/compile_time/concat_append.c3t
@@ -31,6 +31,7 @@ fn int main()
 @.str.5 = private unnamed_addr constant [10 x i8] c"hello... \00", align 1
 @.str.6 = private unnamed_addr constant [8 x i8] c" there!\00", align 1
 @.__const.7 = private unnamed_addr constant [2 x %"char[]"] [%"char[]" { ptr @.str.5, i64 9 }, %"char[]" { ptr @.str.6, i64 7 }], align 16
+@.emptystr = internal constant [1 x i8] zeroinitializer, align 1
 @.str.8 = private unnamed_addr constant [4 x i8] c"bye\00", align 1
 
 define i32 @main() #0 {
@@ -54,7 +55,7 @@ entry:
   %1 = insertvalue %"int[]" %0, i64 3, 1
   store %"int[]" %1, ptr %d, align 8
   call void @llvm.memcpy.p0.p0.i32(ptr align 16 %e, ptr align 16 @.__const.7, i32 32, i1 false)
-  store %"char[]" zeroinitializer, ptr %f, align 8
+  store %"char[]" { ptr @.emptystr, i64 0 }, ptr %f, align 8
   store %"char[]" { ptr @.str.8, i64 3 }, ptr %g, align 8
   store i32 1000299617, ptr %h, align 4
   ret i32 0
diff --git a/test/test_suite/compile_time/ct_forach_with_defer.c3t b/test/test_suite/compile_time/ct_forach_with_defer.c3t
index 7b63a3211..d40711214 100644
--- a/test/test_suite/compile_time/ct_forach_with_defer.c3t
+++ b/test/test_suite/compile_time/ct_forach_with_defer.c3t
@@ -75,13 +75,17 @@ entry:
   %not_err = icmp eq i64 %16, 0
   %17 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
   br i1 %17, label %after_check, label %assign_optional
+
 assign_optional:                                  ; preds = %entry
   store i64 %16, ptr %error_var, align 8
   br label %guard_block
+
 after_check:                                      ; preds = %entry
   br label %noerr_block
+
 guard_block:                                      ; preds = %assign_optional
   br label %voiderr
+
 noerr_block:                                      ; preds = %after_check
   %18 = load i64, ptr %retparam14, align 8
   store i64 %18, ptr %len, align 8
@@ -89,29 +93,38 @@ noerr_block:                                      ; preds = %after_check
   %not_err16 = icmp eq i64 %19, 0
   %20 = call i1 @llvm.expect.i1(i1 %not_err16, i1 true)
   br i1 %20, label %after_check18, label %assign_optional17
+
 assign_optional17:                                ; preds = %noerr_block
   store i64 %19, ptr %error_var15, align 8
   br label %guard_block19
+
 after_check18:                                    ; preds = %noerr_block
   br label %noerr_block20
+
 guard_block19:                                    ; preds = %assign_optional17
   br label %voiderr
+
 noerr_block20:                                    ; preds = %after_check18
   %21 = call i64 @std.io.File.flush(ptr %15)
   %not_err22 = icmp eq i64 %21, 0
   %22 = call i1 @llvm.expect.i1(i1 %not_err22, i1 true)
   br i1 %22, label %after_check24, label %assign_optional23
+
 assign_optional23:                                ; preds = %noerr_block20
   store i64 %21, ptr %error_var21, align 8
   br label %guard_block25
+
 after_check24:                                    ; preds = %noerr_block20
   br label %noerr_block26
+
 guard_block25:                                    ; preds = %assign_optional23
   br label %voiderr
+
 noerr_block26:                                    ; preds = %after_check24
   %23 = load i64, ptr %len, align 8
   %add = add i64 %23, 1
   br label %voiderr
+
 voiderr:                                          ; preds = %noerr_block26, %guard_block25, %guard_block19, %guard_block
   ret void
 }
@@ -169,17 +182,21 @@ entry:
   store %any %13, ptr %varargslots10, align 16
   %14 = call i64 @std.io.printf(ptr %retparam12, ptr @.str.11, i64 2, ptr %varargslots10, i64 1)
   %15 = call ptr @std.io.stdout()
-  %16 = call i64 @std.io.File.write(ptr %retparam14, ptr %15, ptr null, i64 0)
+  %16 = call i64 @std.io.File.write(ptr %retparam14, ptr %15, ptr @.emptystr, i64 0)
   %not_err = icmp eq i64 %16, 0
   %17 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
   br i1 %17, label %after_check, label %assign_optional
+
 assign_optional:                                  ; preds = %entry
   store i64 %16, ptr %error_var, align 8
   br label %guard_block
+
 after_check:                                      ; preds = %entry
   br label %noerr_block
+
 guard_block:                                      ; preds = %assign_optional
   br label %voiderr
+
 noerr_block:                                      ; preds = %after_check
   %18 = load i64, ptr %retparam14, align 8
   store i64 %18, ptr %len, align 8
@@ -187,42 +204,55 @@ noerr_block:                                      ; preds = %after_check
   %not_err16 = icmp eq i64 %19, 0
   %20 = call i1 @llvm.expect.i1(i1 %not_err16, i1 true)
   br i1 %20, label %after_check18, label %assign_optional17
+
 assign_optional17:                                ; preds = %noerr_block
   store i64 %19, ptr %error_var15, align 8
   br label %guard_block19
+
 after_check18:                                    ; preds = %noerr_block
   br label %noerr_block20
+
 guard_block19:                                    ; preds = %assign_optional17
   br label %voiderr
+
 noerr_block20:                                    ; preds = %after_check18
   %21 = call i64 @std.io.File.flush(ptr %15)
   %not_err22 = icmp eq i64 %21, 0
   %22 = call i1 @llvm.expect.i1(i1 %not_err22, i1 true)
   br i1 %22, label %after_check24, label %assign_optional23
+
 assign_optional23:                                ; preds = %noerr_block20
   store i64 %21, ptr %error_var21, align 8
   br label %guard_block25
+
 after_check24:                                    ; preds = %noerr_block20
   br label %noerr_block26
+
 guard_block25:                                    ; preds = %assign_optional23
   br label %voiderr
+
 noerr_block26:                                    ; preds = %after_check24
   %23 = load i64, ptr %len, align 8
   %add = add i64 %23, 1
   br label %voiderr
+
 voiderr:                                          ; preds = %noerr_block26, %guard_block25, %guard_block19, %guard_block
   %24 = call ptr @std.io.stdout()
   %25 = call i64 @std.io.File.write(ptr %retparam30, ptr %24, ptr @.str.12, i64 6)
   %not_err31 = icmp eq i64 %25, 0
   %26 = call i1 @llvm.expect.i1(i1 %not_err31, i1 true)
   br i1 %26, label %after_check33, label %assign_optional32
+
 assign_optional32:                                ; preds = %voiderr
   store i64 %25, ptr %error_var28, align 8
   br label %guard_block34
+
 after_check33:                                    ; preds = %voiderr
   br label %noerr_block35
+
 guard_block34:                                    ; preds = %assign_optional32
   br label %voiderr49
+
 noerr_block35:                                    ; preds = %after_check33
   %27 = load i64, ptr %retparam30, align 8
   store i64 %27, ptr %len27, align 8
@@ -230,29 +260,38 @@ noerr_block35:                                    ; preds = %after_check33
   %not_err37 = icmp eq i64 %28, 0
   %29 = call i1 @llvm.expect.i1(i1 %not_err37, i1 true)
   br i1 %29, label %after_check39, label %assign_optional38
+
 assign_optional38:                                ; preds = %noerr_block35
   store i64 %28, ptr %error_var36, align 8
   br label %guard_block40
+
 after_check39:                                    ; preds = %noerr_block35
   br label %noerr_block41
+
 guard_block40:                                    ; preds = %assign_optional38
   br label %voiderr49
+
 noerr_block41:                                    ; preds = %after_check39
   %30 = call i64 @std.io.File.flush(ptr %24)
   %not_err43 = icmp eq i64 %30, 0
   %31 = call i1 @llvm.expect.i1(i1 %not_err43, i1 true)
   br i1 %31, label %after_check45, label %assign_optional44
+
 assign_optional44:                                ; preds = %noerr_block41
   store i64 %30, ptr %error_var42, align 8
   br label %guard_block46
+
 after_check45:                                    ; preds = %noerr_block41
   br label %noerr_block47
+
 guard_block46:                                    ; preds = %assign_optional44
   br label %voiderr49
+
 noerr_block47:                                    ; preds = %after_check45
   %32 = load i64, ptr %len27, align 8
   %add48 = add i64 %32, 1
   br label %voiderr49
+
 voiderr49:                                        ; preds = %noerr_block47, %guard_block46, %guard_block40, %guard_block34
   ret void
 }
diff --git a/test/test_suite/compile_time/ct_memberof.c3t b/test/test_suite/compile_time/ct_memberof.c3t
index afe68060a..64c39437f 100644
--- a/test/test_suite/compile_time/ct_memberof.c3t
+++ b/test/test_suite/compile_time/ct_memberof.c3t
@@ -114,7 +114,7 @@ entry:
   ret void
 }
 
-; Function Attrs:
+
 define void @test.test(i32 %0) #0 {
 entry:
   %len = alloca i64, align 8
@@ -206,13 +206,17 @@ entry:
   %not_err = icmp eq i64 %2, 0
   %3 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
   br i1 %3, label %after_check, label %assign_optional
+
 assign_optional:                                  ; preds = %entry
   store i64 %2, ptr %error_var, align 8
   br label %guard_block
+
 after_check:                                      ; preds = %entry
   br label %noerr_block
+
 guard_block:                                      ; preds = %assign_optional
   br label %voiderr
+
 noerr_block:                                      ; preds = %after_check
   %4 = load i64, ptr %retparam, align 8
   store i64 %4, ptr %len, align 8
@@ -220,42 +224,55 @@ noerr_block:                                      ; preds = %after_check
   %not_err3 = icmp eq i64 %5, 0
   %6 = call i1 @llvm.expect.i1(i1 %not_err3, i1 true)
   br i1 %6, label %after_check5, label %assign_optional4
+
 assign_optional4:                                 ; preds = %noerr_block
   store i64 %5, ptr %error_var2, align 8
   br label %guard_block6
+
 after_check5:                                     ; preds = %noerr_block
   br label %noerr_block7
+
 guard_block6:                                     ; preds = %assign_optional4
   br label %voiderr
+
 noerr_block7:                                     ; preds = %after_check5
   %7 = call i64 @std.io.File.flush(ptr %1)
   %not_err9 = icmp eq i64 %7, 0
   %8 = call i1 @llvm.expect.i1(i1 %not_err9, i1 true)
   br i1 %8, label %after_check11, label %assign_optional10
+
 assign_optional10:                                ; preds = %noerr_block7
   store i64 %7, ptr %error_var8, align 8
   br label %guard_block12
+
 after_check11:                                    ; preds = %noerr_block7
   br label %noerr_block13
+
 guard_block12:                                    ; preds = %assign_optional10
   br label %voiderr
+
 noerr_block13:                                    ; preds = %after_check11
   %9 = load i64, ptr %len, align 8
   %add = add i64 %9, 1
   br label %voiderr
+
 voiderr:                                          ; preds = %noerr_block13, %guard_block12, %guard_block6, %guard_block
   %10 = call ptr @std.io.stdout()
   %11 = call i64 @std.io.File.write(ptr %retparam17, ptr %10, ptr @.str.10, i64 3)
   %not_err18 = icmp eq i64 %11, 0
   %12 = call i1 @llvm.expect.i1(i1 %not_err18, i1 true)
   br i1 %12, label %after_check20, label %assign_optional19
+
 assign_optional19:                                ; preds = %voiderr
   store i64 %11, ptr %error_var15, align 8
   br label %guard_block21
+
 after_check20:                                    ; preds = %voiderr
   br label %noerr_block22
+
 guard_block21:                                    ; preds = %assign_optional19
   br label %voiderr36
+
 noerr_block22:                                    ; preds = %after_check20
   %13 = load i64, ptr %retparam17, align 8
   store i64 %13, ptr %len14, align 8
@@ -263,6 +280,7 @@ noerr_block22:                                    ; preds = %after_check20
   %not_err24 = icmp eq i64 %14, 0
   %15 = call i1 @llvm.expect.i1(i1 %not_err24, i1 true)
   br i1 %15, label %after_check26, label %assign_optional25
+
 assign_optional25:                                ; preds = %noerr_block22
   store i64 %14, ptr %error_var23, align 8
   br label %guard_block27
@@ -600,7 +618,7 @@ voiderr151:                                       ; preds = %noerr_block149, %gu
   %ptradd164 = getelementptr inbounds i8, ptr %varargslots161, i64 16
   store %any %75, ptr %ptradd164, align 16
   %76 = call i64 @std.io.printfn(ptr %retparam165, ptr @.str.21, i64 6, ptr %varargslots161, i64 2)
-  store %"char[]" zeroinitializer, ptr %taddr169, align 8
+  store %"char[]" { ptr @.emptystr, i64 0 }, ptr %taddr169, align 8
   %77 = insertvalue %any undef, ptr %taddr169, 0
   %78 = insertvalue %any %77, i64 ptrtoint (ptr @"$ct.String" to i64), 1
   store %any %78, ptr %varargslots168, align 16
@@ -645,7 +663,7 @@ voiderr151:                                       ; preds = %noerr_block149, %gu
   %ptradd197 = getelementptr inbounds i8, ptr %varargslots194, i64 16
   store %any %98, ptr %ptradd197, align 16
   %99 = call i64 @std.io.printfn(ptr %retparam198, ptr @.str.34, i64 6, ptr %varargslots194, i64 2)
-  store %"char[]" zeroinitializer, ptr %taddr202, align 8
+  store %"char[]" { ptr @.emptystr, i64 0 }, ptr %taddr202, align 8
   %100 = insertvalue %any undef, ptr %taddr202, 0
   %101 = insertvalue %any %100, i64 ptrtoint (ptr @"$ct.String" to i64), 1
   store %any %101, ptr %varargslots201, align 16
@@ -693,7 +711,7 @@ voiderr151:                                       ; preds = %noerr_block149, %gu
   ret void
 }
 
-; Function Attrs: nounwind uwtable
+
 define void @test.main() #0 {
 entry:
   %varargslots = alloca [1 x %any], align 16
@@ -836,19 +854,23 @@ entry:
   ret void
 }
 
-; Function Attrs: nounwind uwtable
+
 define i32 @main(i32 %0, ptr %1) #0 {
 entry:
   call void @test.main()
   ret i32 0
 }
 
+
 declare extern_weak ptr @std.io.stdout() #0
 
+
 declare extern_weak i64 @std.io.File.write(ptr, ptr, ptr, i64) #0
 
 declare extern_weak i64 @std.io.File.write_byte(ptr, i8 zeroext) #0
 
+
 declare extern_weak i64 @std.io.File.flush(ptr) #0
 
+
 declare extern_weak i64 @std.io.printfn(ptr, ptr, i64, ptr, i64) #0
diff --git a/test/test_suite/errors/error_regression_2.c3t b/test/test_suite/errors/error_regression_2.c3t
index 4e5437951..906c93653 100644
--- a/test/test_suite/errors/error_regression_2.c3t
+++ b/test/test_suite/errors/error_regression_2.c3t
@@ -173,7 +173,6 @@ cond.phi:                                         ; preds = %cond.rhs, %cond.lhs
   ret void
 }
 
-; Function Attrs:
 define zeroext i8 @test.contains(ptr %0, i64 %1, ptr %2, i64 %3) #0 {
 entry:
   %haystack = alloca %"char[]", align 8
@@ -247,7 +246,6 @@ loop.exit:                                        ; preds = %loop.cond
   ret i8 0
 }
 
-; Function Attrs:
 define i64 @test.readDoc(ptr %0, ptr %1, i64 %2) #0 {
 entry:
   %url = alloca %"char[]", align 8
@@ -351,7 +349,7 @@ if.exit16:                                        ; preds = %if.exit6
 
 if.then20:                                        ; preds = %if.exit16
   store ptr null, ptr %literal24, align 8
-  store %"char[]" zeroinitializer, ptr %value26, align 8
+  store %"char[]" { ptr @.emptystr, i64 0 }, ptr %value26, align 8
   %16 = call ptr @std.core.mem.malloc(i64 16) #3
   store ptr %16, ptr %temp27, align 8
   %17 = load ptr, ptr %temp27, align 8
@@ -486,7 +484,6 @@ noerr_block66:                                    ; preds = %if.exit64
   ret i64 0
 }
 
-; Function Attrs:
 define { ptr, i8 } @test.buildSummary(ptr %0) #0 {
 entry:
   %doc = alloca %Doc, align 8
@@ -516,7 +513,6 @@ cond.phi:                                         ; preds = %cond.rhs, %cond.lhs
   ret { ptr, i8 } %4
 }
 
-; Function Attrs:
 define { ptr, i8 } @test.readAndBuildSummary(ptr %0, i64 %1) #0 {
 entry:
   %url = alloca %"char[]", align 8
@@ -550,7 +546,6 @@ phi_block:                                        ; preds = %else_block, %after_
   ret { ptr, i8 } %6
 }
 
-; Function Attrs:
 define i64 @test.isTitleNonEmpty(ptr %0, ptr %1) #0 {
 entry:
   %doc = alloca %Doc, align 8
@@ -585,7 +580,7 @@ if.exit3:                                         ; preds = %if.exit
   ret i64 0
 }
 
-; Function Attrs:
+
 define i64 @test.readWhetherTitleNonEmpty(ptr %0, ptr %1, i64 %2) #0 {
 entry:
   %url = alloca %"char[]", align 8
@@ -628,7 +623,7 @@ err_retblock:                                     ; preds = %assign_optional4, %
   ret i64 %9
 }
 
-; Function Attrs:
+
 define ptr @test.bool_to_string(i8 zeroext %0) #0 {
 entry:
   %1 = trunc i8 %0 to i1
@@ -636,7 +631,7 @@ entry:
   ret ptr %ternary
 }
 
-; Function Attrs:
+
 define ptr @test.nameFromError(i64 %0) #0 {
 entry:
   %switch = alloca i64, align 8
@@ -672,7 +667,7 @@ switch.default:                                   ; preds = %next_if6
   ret ptr @.str.13
 }
 
-; Function Attrs:
+
 define void @test.main() #0 {
 entry:
   %.anon = alloca i64, align 8
@@ -727,7 +722,7 @@ cond.rhs:                                         ; preds = %loop.body
   br label %cond.phi
 
 cond.phi:                                         ; preds = %cond.rhs, %cond.lhs
-  %val = phi %"char[]" [ %13, %cond.lhs ], [ zeroinitializer, %cond.rhs ]
+  %val = phi %"char[]" [ %13, %cond.lhs ], [ { ptr @.emptystr, i64 0 }, %cond.rhs ]
   store %"char[]" %val, ptr %title_sure, align 8
   %ptradd2 = getelementptr inbounds i8, ptr %title_sure, i64 8
   %14 = load i64, ptr %ptradd2, align 8
diff --git a/test/test_suite/from_docs/examples_defer.c3t b/test/test_suite/from_docs/examples_defer.c3t
index d634771af..8466691fe 100644
--- a/test/test_suite/from_docs/examples_defer.c3t
+++ b/test/test_suite/from_docs/examples_defer.c3t
@@ -53,7 +53,7 @@ if.then:                                          ; preds = %entry
   %1 = call ptr @std.io.stdout()
   %2 = call i64 @std.io.File.write(ptr %retparam, ptr %1, ptr @.str, i64 1)
   %3 = call ptr @std.io.stdout()
-  %4 = call i64 @std.io.File.write(ptr %retparam2, ptr %3, ptr null, i64 0)
+  %4 = call i64 @std.io.File.write(ptr %retparam2, ptr %3, ptr @.emptystr, i64 0)
   %not_err = icmp eq i64 %4, 0
   %5 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
   br i1 %5, label %after_check, label %assign_optional
@@ -120,7 +120,7 @@ if.then16:                                        ; preds = %if.exit
   %14 = call ptr @std.io.stdout()
   %15 = call i64 @std.io.File.write(ptr %retparam20, ptr %14, ptr @.str.2, i64 1)
   %16 = call ptr @std.io.stdout()
-  %17 = call i64 @std.io.File.write(ptr %retparam26, ptr %16, ptr null, i64 0)
+  %17 = call i64 @std.io.File.write(ptr %retparam26, ptr %16, ptr @.emptystr, i64 0)
   %not_err27 = icmp eq i64 %17, 0
   %18 = call i1 @llvm.expect.i1(i1 %not_err27, i1 true)
   br i1 %18, label %after_check29, label %assign_optional28
@@ -185,7 +185,7 @@ if.exit46:                                        ; preds = %if.exit
   %29 = call ptr @std.io.stdout()
   %30 = call i64 @std.io.File.write(ptr %retparam53, ptr %29, ptr @.str.5, i64 1)
   %31 = call ptr @std.io.stdout()
-  %32 = call i64 @std.io.File.write(ptr %retparam59, ptr %31, ptr null, i64 0)
+  %32 = call i64 @std.io.File.write(ptr %retparam59, ptr %31, ptr @.emptystr, i64 0)
   %not_err60 = icmp eq i64 %32, 0
   %33 = call i1 @llvm.expect.i1(i1 %not_err60, i1 true)
   br i1 %33, label %after_check62, label %assign_optional61
diff --git a/test/test_suite/struct/init_cont_struct_array_locally.c3t b/test/test_suite/struct/init_cont_struct_array_locally.c3t
index b56588b26..66282d803 100644
--- a/test/test_suite/struct/init_cont_struct_array_locally.c3t
+++ b/test/test_suite/struct/init_cont_struct_array_locally.c3t
@@ -59,15 +59,19 @@ entry:
   %not_err = icmp eq i64 %3, 0
   %4 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
   br i1 %4, label %after_check, label %assign_optional
+
 assign_optional:                                  ; preds = %entry
   store i64 %3, ptr %error_var5, align 8
   br label %guard_block
+
 after_check:                                      ; preds = %entry
   br label %noerr_block
+
 guard_block:                                      ; preds = %assign_optional
   %5 = load i64, ptr %error_var5, align 8
   store i64 %5, ptr %error_var, align 8
   br label %guard_block28
+
 noerr_block:                                      ; preds = %after_check
   %6 = load i64, ptr %retparam, align 8
   store i64 %6, ptr %total, align 8
@@ -80,15 +84,19 @@ noerr_block:                                      ; preds = %after_check
   %not_err9 = icmp eq i64 %10, 0
   %11 = call i1 @llvm.expect.i1(i1 %not_err9, i1 true)
   br i1 %11, label %after_check11, label %assign_optional10
+
 assign_optional10:                                ; preds = %noerr_block
   store i64 %10, ptr %error_var6, align 8
   br label %guard_block12
+
 after_check11:                                    ; preds = %noerr_block
   br label %noerr_block13
+
 guard_block12:                                    ; preds = %assign_optional10
   %12 = load i64, ptr %error_var6, align 8
   store i64 %12, ptr %error_var, align 8
   br label %guard_block28
+
 noerr_block13:                                    ; preds = %after_check11
   %13 = load i64, ptr %retparam8, align 8
   %add = add i64 %7, %13
@@ -101,15 +109,19 @@ noerr_block13:                                    ; preds = %after_check11
   %not_err17 = icmp eq i64 %17, 0
   %18 = call i1 @llvm.expect.i1(i1 %not_err17, i1 true)
   br i1 %18, label %after_check19, label %assign_optional18
+
 assign_optional18:                                ; preds = %noerr_block13
   store i64 %17, ptr %error_var14, align 8
   br label %guard_block20
+
 after_check19:                                    ; preds = %noerr_block13
   br label %noerr_block21
+
 guard_block20:                                    ; preds = %assign_optional18
   %19 = load i64, ptr %error_var14, align 8
   store i64 %19, ptr %error_var, align 8
   br label %guard_block28
+
 noerr_block21:                                    ; preds = %after_check19
   %20 = load i64, ptr %retparam16, align 8
   %add22 = add i64 %14, %20
@@ -119,58 +131,75 @@ noerr_block21:                                    ; preds = %after_check19
   %not_err24 = icmp eq i64 %22, 0
   %23 = call i1 @llvm.expect.i1(i1 %not_err24, i1 true)
   br i1 %23, label %after_check26, label %assign_optional25
+
 assign_optional25:                                ; preds = %noerr_block21
   store i64 %22, ptr %error_var, align 8
   br label %guard_block28
+
 after_check26:                                    ; preds = %noerr_block21
   %24 = load i64, ptr %retparam23, align 8
   %add27 = add i64 %21, %24
   br label %noerr_block29
+
 guard_block28:                                    ; preds = %assign_optional25, %guard_block20, %guard_block12, %guard_block
   br label %voiderr
+
 noerr_block29:                                    ; preds = %after_check26
   store i64 %add27, ptr %len, align 8
   %25 = call i64 @std.io.File.write_byte(ptr %0, i8 zeroext 10)
   %not_err31 = icmp eq i64 %25, 0
   %26 = call i1 @llvm.expect.i1(i1 %not_err31, i1 true)
   br i1 %26, label %after_check33, label %assign_optional32
+
 assign_optional32:                                ; preds = %noerr_block29
   store i64 %25, ptr %error_var30, align 8
   br label %guard_block34
+
 after_check33:                                    ; preds = %noerr_block29
   br label %noerr_block35
+
 guard_block34:                                    ; preds = %assign_optional32
   br label %voiderr
+
 noerr_block35:                                    ; preds = %after_check33
   %27 = call i64 @std.io.File.flush(ptr %0)
   %not_err37 = icmp eq i64 %27, 0
   %28 = call i1 @llvm.expect.i1(i1 %not_err37, i1 true)
   br i1 %28, label %after_check39, label %assign_optional38
+
 assign_optional38:                                ; preds = %noerr_block35
   store i64 %27, ptr %error_var36, align 8
   br label %guard_block40
+
 after_check39:                                    ; preds = %noerr_block35
   br label %noerr_block41
+
 guard_block40:                                    ; preds = %assign_optional38
   br label %voiderr
+
 noerr_block41:                                    ; preds = %after_check39
   %29 = load i64, ptr %len, align 8
   %add42 = add i64 %29, 1
   br label %voiderr
+
 voiderr:                                          ; preds = %noerr_block41, %guard_block40, %guard_block34, %guard_block28
   call void @llvm.memcpy.p0.p0.i32(ptr align 1 %y, ptr align 1 @.__const, i32 2, i1 false)
   %30 = call ptr @std.io.stdout()
-  %31 = call i64 @std.io.File.write(ptr %retparam46, ptr %30, ptr null, i64 0)
+  %31 = call i64 @std.io.File.write(ptr %retparam46, ptr %30, ptr @.emptystr, i64 0)
   %not_err47 = icmp eq i64 %31, 0
   %32 = call i1 @llvm.expect.i1(i1 %not_err47, i1 true)
   br i1 %32, label %after_check49, label %assign_optional48
+
 assign_optional48:                                ; preds = %voiderr
   store i64 %31, ptr %error_var44, align 8
   br label %guard_block50
+
 after_check49:                                    ; preds = %voiderr
   br label %noerr_block51
+
 guard_block50:                                    ; preds = %assign_optional48
   br label %voiderr65
+
 noerr_block51:                                    ; preds = %after_check49
   %33 = load i64, ptr %retparam46, align 8
   store i64 %33, ptr %len43, align 8
@@ -178,29 +207,38 @@ noerr_block51:                                    ; preds = %after_check49
   %not_err53 = icmp eq i64 %34, 0
   %35 = call i1 @llvm.expect.i1(i1 %not_err53, i1 true)
   br i1 %35, label %after_check55, label %assign_optional54
+
 assign_optional54:                                ; preds = %noerr_block51
   store i64 %34, ptr %error_var52, align 8
   br label %guard_block56
+
 after_check55:                                    ; preds = %noerr_block51
   br label %noerr_block57
+
 guard_block56:                                    ; preds = %assign_optional54
   br label %voiderr65
+
 noerr_block57:                                    ; preds = %after_check55
   %36 = call i64 @std.io.File.flush(ptr %30)
   %not_err59 = icmp eq i64 %36, 0
   %37 = call i1 @llvm.expect.i1(i1 %not_err59, i1 true)
   br i1 %37, label %after_check61, label %assign_optional60
+
 assign_optional60:                                ; preds = %noerr_block57
   store i64 %36, ptr %error_var58, align 8
   br label %guard_block62
+
 after_check61:                                    ; preds = %noerr_block57
   br label %noerr_block63
+
 guard_block62:                                    ; preds = %assign_optional60
   br label %voiderr65
+
 noerr_block63:                                    ; preds = %after_check61
   %38 = load i64, ptr %len43, align 8
   %add64 = add i64 %38, 1
   br label %voiderr65
+
 voiderr65:                                        ; preds = %noerr_block63, %guard_block62, %guard_block56, %guard_block50
   ret i32 0
 }