From 52b8b92095a1d9b7af441e697cc05e0df3f1d2a7 Mon Sep 17 00:00:00 2001
From: CountBleck <Mr.YouKnowWhoIAm@protonmail.com>
Date: Mon, 2 Jun 2025 21:37:50 -0700
Subject: [PATCH] fix: allow using nullable strings in template literals

We basically compile nullable strings down to a ternary:
`expr ? expr.toString() : "null"`

Fixes #2918.
---
 src/compiler.ts                            |  32 ++-
 tests/compiler/templateliteral.debug.wat   | 160 +++++++++++--
 tests/compiler/templateliteral.release.wat | 255 ++++++++++++++-------
 tests/compiler/templateliteral.ts          |   7 +
 4 files changed, 350 insertions(+), 104 deletions(-)

diff --git a/src/compiler.ts b/src/compiler.ts
index 246993f1cd..dbcb600dc8 100644
--- a/src/compiler.ts
+++ b/src/compiler.ts
@@ -10145,6 +10145,7 @@ export class Compiler extends DiagnosticEmitter {
 
   /** Makes a string conversion of the given expression. */
   makeToString(expr: ExpressionRef, type: Type, reportNode: Node): ExpressionRef {
+    let module = this.module;
     let stringType = this.program.stringInstance.type;
     if (type == stringType) {
       return expr;
@@ -10161,15 +10162,30 @@ export class Compiler extends DiagnosticEmitter {
           reportNode
         )) {
           this.currentType = stringType;
-          return this.module.unreachable();
+          return module.unreachable();
         }
         if (!type.isStrictlyAssignableTo(assert(toStringSignature.thisType))) {
-          this.errorRelated(
-            DiagnosticCode.The_this_types_of_each_signature_are_incompatible,
-            reportNode.range, toStringInstance.identifierAndSignatureRange
+          if (!type.is(TypeFlags.Nullable)) {
+            this.errorRelated(
+              DiagnosticCode.The_this_types_of_each_signature_are_incompatible,
+              reportNode.range, toStringInstance.identifierAndSignatureRange
+            );
+            this.currentType = stringType;
+            return module.unreachable();
+          }
+
+          // Attempt to retry on the non-nullable form of the type, wrapped in a ternary:
+          // `expr ? expr.toString() : "null"`
+          const tempLocal = this.currentFlow.getTempLocal(type);
+          return module.if(
+            module.local_tee(tempLocal.index, expr, type.isManaged),
+            this.makeToString(
+              module.local_get(tempLocal.index, type.toRef()),
+              type.nonNullableType,
+              reportNode
+            ),
+            this.ensureStaticString("null")
           );
-          this.currentType = stringType;
-          return this.module.unreachable();
         }
         let toStringReturnType = toStringSignature.returnType;
         if (!toStringReturnType.isStrictlyAssignableTo(stringType)) {
@@ -10178,7 +10194,7 @@ export class Compiler extends DiagnosticEmitter {
             reportNode.range, toStringInstance.identifierAndSignatureRange, toStringReturnType.toString(), stringType.toString()
           );
           this.currentType = stringType;
-          return this.module.unreachable();
+          return module.unreachable();
         }
         return this.makeCallDirect(toStringInstance, [ expr ], reportNode);
       }
@@ -10188,7 +10204,7 @@ export class Compiler extends DiagnosticEmitter {
       reportNode.range, type.toString(), stringType.toString()
     );
     this.currentType = stringType;
-    return this.module.unreachable();
+    return module.unreachable();
   }
 
   /** Makes an allocation suitable to hold the data of an instance of the given class. */
diff --git a/tests/compiler/templateliteral.debug.wat b/tests/compiler/templateliteral.debug.wat
index 629dbcd62d..4ba00fcccb 100644
--- a/tests/compiler/templateliteral.debug.wat
+++ b/tests/compiler/templateliteral.debug.wat
@@ -39,10 +39,10 @@
  (global $~lib/util/number/_K (mut i32) (i32.const 0))
  (global $~lib/util/number/_frc_pow (mut i64) (i64.const 0))
  (global $~lib/util/number/_exp_pow (mut i32) (i32.const 0))
- (global $~lib/rt/__rtti_base i32 (i32.const 4640))
- (global $~lib/memory/__data_end i32 (i32.const 4672))
- (global $~lib/memory/__stack_pointer (mut i32) (i32.const 37440))
- (global $~lib/memory/__heap_base i32 (i32.const 37440))
+ (global $~lib/rt/__rtti_base i32 (i32.const 4848))
+ (global $~lib/memory/__data_end i32 (i32.const 4880))
+ (global $~lib/memory/__stack_pointer (mut i32) (i32.const 37648))
+ (global $~lib/memory/__heap_base i32 (i32.const 37648))
  (global $~started (mut i32) (i32.const 0))
  (memory $0 1)
  (data $0 (i32.const 12) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\02\00\00\00a\00\00\00\00\00\00\00\00\00\00\00")
@@ -98,11 +98,16 @@
  (data $50 (i32.const 4348) ",\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\14\00\00\00r\00e\00f\00#\001\00r\00e\00f\00#\002\00\00\00\00\00\00\00\00\00")
  (data $51 (i32.const 4396) ",\00\00\00\03\00\00\00\00\00\00\00\04\00\00\00\14\00\00\00p\02\00\00\00\00\00\00\90\02\00\00\00\00\00\00\b0\02\00\00\00\00\00\00\00\00\00\00")
  (data $52 (i32.const 4444) "<\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00$\00\00\00(\00A\00=\00r\00e\00f\00#\001\00,\00 \00B\00=\00r\00e\00f\00#\002\00)\00\00\00\00\00\00\00\00\00")
- (data $53 (i32.const 4508) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\02\00\00\00c\00\00\00\00\00\00\00\00\00\00\00")
- (data $54 (i32.const 4540) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\02\00\00\00:\00\00\00\00\00\00\00\00\00\00\00")
- (data $55 (i32.const 4572) "\1c\00\00\00\03\00\00\00\00\00\00\00\04\00\00\00\0c\00\00\00\00\00\00\00\d0\11\00\00\00\00\00\00")
- (data $56 (i32.const 4604) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\n\00\00\00a\00:\00b\00:\00c\00\00\00")
- (data $57 (i32.const 4640) "\07\00\00\00 \00\00\00 \00\00\00 \00\00\00\00\00\00\00\04A\00\00 \00\00\00\00\00\00\00")
+ (data $53 (i32.const 4508) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\06\00\00\00c\00:\00 \00\00\00\00\00\00\00")
+ (data $54 (i32.const 4540) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\n\00\00\00;\00 \00d\00:\00 \00\00\00")
+ (data $55 (i32.const 4572) ",\00\00\00\03\00\00\00\00\00\00\00\04\00\00\00\10\00\00\00\b0\11\00\00\00\00\00\00\d0\11\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
+ (data $56 (i32.const 4620) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\08\00\00\00n\00u\00l\00l\00\00\00\00\00")
+ (data $57 (i32.const 4652) "<\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\"\00\00\00c\00:\00 \00r\00e\00f\00#\003\00;\00 \00d\00:\00 \00n\00u\00l\00l\00\00\00\00\00\00\00\00\00\00\00")
+ (data $58 (i32.const 4716) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\02\00\00\00c\00\00\00\00\00\00\00\00\00\00\00")
+ (data $59 (i32.const 4748) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\02\00\00\00:\00\00\00\00\00\00\00\00\00\00\00")
+ (data $60 (i32.const 4780) "\1c\00\00\00\03\00\00\00\00\00\00\00\04\00\00\00\0c\00\00\00\00\00\00\00\a0\12\00\00\00\00\00\00")
+ (data $61 (i32.const 4812) "\1c\00\00\00\00\00\00\00\00\00\00\00\02\00\00\00\n\00\00\00a\00:\00b\00:\00c\00\00\00")
+ (data $62 (i32.const 4848) "\07\00\00\00 \00\00\00 \00\00\00 \00\00\00\00\00\00\00\04A\00\00 \00\00\00\00\00\00\00")
  (table $0 1 1 funcref)
  (elem $0 (i32.const 1))
  (export "memory" (memory $0))
@@ -4365,6 +4370,7 @@
   call $templateliteral/test_float
   call $templateliteral/test_fast_paths_string
   call $templateliteral/test_ref
+  call $templateliteral/test_null
   call $templateliteral/test_recursive
  )
  (func $~lib/rt/__visit_globals (param $0 i32)
@@ -4519,8 +4525,8 @@
   global.get $~lib/memory/__data_end
   i32.lt_s
   if
-   i32.const 37472
-   i32.const 37520
+   i32.const 37680
+   i32.const 37728
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -5991,6 +5997,126 @@
   i32.add
   global.set $~lib/memory/__stack_pointer
  )
+ (func $templateliteral/test_null
+  (local $c i32)
+  (local $d i32)
+  (local $2 i32)
+  (local $3 i32)
+  (local $4 i32)
+  (local $5 i32)
+  global.get $~lib/memory/__stack_pointer
+  i32.const 32
+  i32.sub
+  global.set $~lib/memory/__stack_pointer
+  call $~stack_check
+  global.get $~lib/memory/__stack_pointer
+  i32.const 0
+  i32.const 32
+  memory.fill
+  global.get $~lib/memory/__stack_pointer
+  i32.const 0
+  i32.const 3
+  call $templateliteral/Ref#constructor
+  local.tee $c
+  i32.store
+  i32.const 0
+  local.set $d
+  global.get $~lib/memory/__stack_pointer
+  local.get $c
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=12
+  local.get $5
+  call $templateliteral/Ref#toString
+  local.tee $2
+  i32.store offset=16
+  global.get $~lib/memory/__stack_pointer
+  global.get $~lib/memory/__stack_pointer
+  local.get $d
+  local.tee $4
+  i32.store offset=20
+  local.get $4
+  if (result i32)
+   local.get $4
+   local.set $5
+   global.get $~lib/memory/__stack_pointer
+   local.get $5
+   i32.store offset=12
+   local.get $5
+   call $templateliteral/Ref#toString
+  else
+   i32.const 4640
+  end
+  local.tee $3
+  i32.store offset=24
+  i32.const 4592
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=12
+  local.get $5
+  i32.const 1
+  local.get $2
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=28
+  local.get $5
+  call $~lib/staticarray/StaticArray<~lib/string/String>#__uset
+  i32.const 4592
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=12
+  local.get $5
+  i32.const 3
+  local.get $3
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=28
+  local.get $5
+  call $~lib/staticarray/StaticArray<~lib/string/String>#__uset
+  i32.const 4592
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=12
+  local.get $5
+  i32.const 160
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=28
+  local.get $5
+  call $~lib/staticarray/StaticArray<~lib/string/String>#join
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=4
+  local.get $5
+  i32.const 4672
+  local.set $5
+  global.get $~lib/memory/__stack_pointer
+  local.get $5
+  i32.store offset=8
+  local.get $5
+  call $~lib/string/String.__eq
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 96
+   i32.const 60
+   i32.const 3
+   call $~lib/builtins/abort
+   unreachable
+  end
+  global.get $~lib/memory/__stack_pointer
+  i32.const 32
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+ )
  (func $templateliteral/RecursiveObject#constructor (param $this i32) (param $key i32) (param $val i32) (result i32)
   (local $3 i32)
   global.get $~lib/memory/__stack_pointer
@@ -6110,7 +6236,7 @@
   call $templateliteral/RecursiveObject#toString
   local.tee $3
   i32.store offset=12
-  i32.const 4592
+  i32.const 4800
   local.set $4
   global.get $~lib/memory/__stack_pointer
   local.get $4
@@ -6124,7 +6250,7 @@
   i32.store offset=16
   local.get $4
   call $~lib/staticarray/StaticArray<~lib/string/String>#__uset
-  i32.const 4592
+  i32.const 4800
   local.set $4
   global.get $~lib/memory/__stack_pointer
   local.get $4
@@ -6138,7 +6264,7 @@
   i32.store offset=16
   local.get $4
   call $~lib/staticarray/StaticArray<~lib/string/String>#__uset
-  i32.const 4592
+  i32.const 4800
   local.set $4
   global.get $~lib/memory/__stack_pointer
   local.get $4
@@ -6175,7 +6301,7 @@
   memory.fill
   global.get $~lib/memory/__stack_pointer
   i32.const 0
-  i32.const 4528
+  i32.const 4736
   local.set $3
   global.get $~lib/memory/__stack_pointer
   local.get $3
@@ -6231,7 +6357,7 @@
   local.get $3
   i32.store
   local.get $3
-  i32.const 4624
+  i32.const 4832
   local.set $3
   global.get $~lib/memory/__stack_pointer
   local.get $3
@@ -6242,7 +6368,7 @@
   if
    i32.const 0
    i32.const 96
-   i32.const 118
+   i32.const 125
    i32.const 3
    call $~lib/builtins/abort
    unreachable
diff --git a/tests/compiler/templateliteral.release.wat b/tests/compiler/templateliteral.release.wat
index a2ded6a5ae..2b8c925ca0 100644
--- a/tests/compiler/templateliteral.release.wat
+++ b/tests/compiler/templateliteral.release.wat
@@ -28,7 +28,7 @@
  (global $~lib/util/number/_K (mut i32) (i32.const 0))
  (global $~lib/util/number/_frc_pow (mut i64) (i64.const 0))
  (global $~lib/util/number/_exp_pow (mut i32) (i32.const 0))
- (global $~lib/memory/__stack_pointer (mut i32) (i32.const 38464))
+ (global $~lib/memory/__stack_pointer (mut i32) (i32.const 38672))
  (global $~started (mut i32) (i32.const 0))
  (memory $0 1)
  (data $0 (i32.const 1036) "\1c")
@@ -122,13 +122,22 @@
  (data $52 (i32.const 5468) "<")
  (data $52.1 (i32.const 5480) "\02\00\00\00$\00\00\00(\00A\00=\00r\00e\00f\00#\001\00,\00 \00B\00=\00r\00e\00f\00#\002\00)")
  (data $53 (i32.const 5532) "\1c")
- (data $53.1 (i32.const 5544) "\02\00\00\00\02\00\00\00c")
+ (data $53.1 (i32.const 5544) "\02\00\00\00\06\00\00\00c\00:\00 ")
  (data $54 (i32.const 5564) "\1c")
- (data $54.1 (i32.const 5576) "\02\00\00\00\02\00\00\00:")
- (data $55 (i32.const 5596) "\1c\00\00\00\03\00\00\00\00\00\00\00\04\00\00\00\0c\00\00\00\00\00\00\00\d0\15")
- (data $56 (i32.const 5628) "\1c")
- (data $56.1 (i32.const 5640) "\02\00\00\00\n\00\00\00a\00:\00b\00:\00c")
- (data $57 (i32.const 5664) "\07\00\00\00 \00\00\00 \00\00\00 \00\00\00\00\00\00\00\04A\00\00 ")
+ (data $54.1 (i32.const 5576) "\02\00\00\00\n\00\00\00;\00 \00d\00:\00 ")
+ (data $55 (i32.const 5596) ",\00\00\00\03\00\00\00\00\00\00\00\04\00\00\00\10\00\00\00\b0\15\00\00\00\00\00\00\d0\15")
+ (data $56 (i32.const 5644) "\1c")
+ (data $56.1 (i32.const 5656) "\02\00\00\00\08\00\00\00n\00u\00l\00l")
+ (data $57 (i32.const 5676) "<")
+ (data $57.1 (i32.const 5688) "\02\00\00\00\"\00\00\00c\00:\00 \00r\00e\00f\00#\003\00;\00 \00d\00:\00 \00n\00u\00l\00l")
+ (data $58 (i32.const 5740) "\1c")
+ (data $58.1 (i32.const 5752) "\02\00\00\00\02\00\00\00c")
+ (data $59 (i32.const 5772) "\1c")
+ (data $59.1 (i32.const 5784) "\02\00\00\00\02\00\00\00:")
+ (data $60 (i32.const 5804) "\1c\00\00\00\03\00\00\00\00\00\00\00\04\00\00\00\0c\00\00\00\00\00\00\00\a0\16")
+ (data $61 (i32.const 5836) "\1c")
+ (data $61.1 (i32.const 5848) "\02\00\00\00\n\00\00\00a\00:\00b\00:\00c")
+ (data $62 (i32.const 5872) "\07\00\00\00 \00\00\00 \00\00\00 \00\00\00\00\00\00\00\04A\00\00 ")
  (export "memory" (memory $0))
  (export "_start" (func $~start))
  (func $~lib/rt/itcms/visitRoots
@@ -203,7 +212,7 @@
    local.get $1
    global.set $~lib/rt/itcms/iter
   end
-  block $__inlined_func$~lib/rt/itcms/Object#unlink$162
+  block $__inlined_func$~lib/rt/itcms/Object#unlink$164
    local.get $0
    i32.load offset=4
    i32.const -4
@@ -215,7 +224,7 @@
     i32.load offset=8
     i32.eqz
     local.get $0
-    i32.const 38464
+    i32.const 38672
     i32.lt_u
     i32.and
     i32.eqz
@@ -227,7 +236,7 @@
      call $~lib/builtins/abort
      unreachable
     end
-    br $__inlined_func$~lib/rt/itcms/Object#unlink$162
+    br $__inlined_func$~lib/rt/itcms/Object#unlink$164
    end
    local.get $0
    i32.load offset=8
@@ -264,7 +273,7 @@
    i32.const 1
   else
    local.get $1
-   i32.const 5664
+   i32.const 5872
    i32.load
    i32.gt_u
    if
@@ -278,7 +287,7 @@
    local.get $1
    i32.const 2
    i32.shl
-   i32.const 5668
+   i32.const 5876
    i32.add
    i32.load
    i32.const 32
@@ -862,10 +871,10 @@
   if
    unreachable
   end
-  i32.const 38464
+  i32.const 38672
   i32.const 0
   i32.store
-  i32.const 40032
+  i32.const 40240
   i32.const 0
   i32.store
   loop $for-loop|0
@@ -876,7 +885,7 @@
     local.get $0
     i32.const 2
     i32.shl
-    i32.const 38464
+    i32.const 38672
     i32.add
     i32.const 0
     i32.store offset=4
@@ -894,7 +903,7 @@
       i32.add
       i32.const 2
       i32.shl
-      i32.const 38464
+      i32.const 38672
       i32.add
       i32.const 0
       i32.store offset=96
@@ -912,14 +921,14 @@
     br $for-loop|0
    end
   end
-  i32.const 38464
-  i32.const 40036
+  i32.const 38672
+  i32.const 40244
   memory.size
   i64.extend_i32_s
   i64.const 16
   i64.shl
   call $~lib/rt/tlsf/addMemory
-  i32.const 38464
+  i32.const 38672
   global.set $~lib/rt/tlsf/ROOT
  )
  (func $~lib/rt/itcms/step (result i32)
@@ -1004,7 +1013,7 @@
      local.set $0
      loop $while-continue|0
       local.get $0
-      i32.const 38464
+      i32.const 38672
       i32.lt_u
       if
        local.get $0
@@ -1100,7 +1109,7 @@
      unreachable
     end
     local.get $0
-    i32.const 38464
+    i32.const 38672
     i32.lt_u
     if
      local.get $0
@@ -1123,7 +1132,7 @@
      i32.const 4
      i32.add
      local.tee $0
-     i32.const 38464
+     i32.const 38672
      i32.ge_u
      if
       global.get $~lib/rt/tlsf/ROOT
@@ -1801,11 +1810,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -2949,11 +2958,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -3020,7 +3029,7 @@
   memory.size
   i32.const 16
   i32.shl
-  i32.const 38464
+  i32.const 38672
   i32.sub
   i32.const 1
   i32.shr_u
@@ -3055,7 +3064,7 @@
   global.set $~lib/memory/__stack_pointer
   block $folding-inner1
    global.get $~lib/memory/__stack_pointer
-   i32.const 5696
+   i32.const 5904
    i32.lt_s
    br_if $folding-inner1
    global.get $~lib/memory/__stack_pointer
@@ -3182,7 +3191,7 @@
    i32.sub
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
-   i32.const 5696
+   i32.const 5904
    i32.lt_s
    br_if $folding-inner1
    global.get $~lib/memory/__stack_pointer
@@ -3316,7 +3325,7 @@
    i32.sub
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
-   i32.const 5696
+   i32.const 5904
    i32.lt_s
    br_if $folding-inner1
    global.get $~lib/memory/__stack_pointer
@@ -3451,7 +3460,7 @@
    i32.sub
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
-   i32.const 5696
+   i32.const 5904
    i32.lt_s
    br_if $folding-inner1
    global.get $~lib/memory/__stack_pointer
@@ -3606,11 +3615,99 @@
    i32.add
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
-   i32.const 24
+   i32.const 32
    i32.sub
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
+   i32.const 5904
+   i32.lt_s
+   br_if $folding-inner1
+   global.get $~lib/memory/__stack_pointer
+   i32.const 0
+   i32.const 32
+   memory.fill
+   global.get $~lib/memory/__stack_pointer
+   i32.const 3
+   call $templateliteral/Ref#constructor
+   local.tee $0
+   i32.store
+   global.get $~lib/memory/__stack_pointer
+   local.get $0
+   i32.store offset=12
+   global.get $~lib/memory/__stack_pointer
+   local.get $0
+   call $templateliteral/Ref#toString
+   local.tee $0
+   i32.store offset=16
+   global.get $~lib/memory/__stack_pointer
+   i32.const 0
+   i32.store offset=20
+   global.get $~lib/memory/__stack_pointer
+   i32.const 5664
+   i32.store offset=24
+   global.get $~lib/memory/__stack_pointer
+   i32.const 5616
+   i32.store offset=12
+   global.get $~lib/memory/__stack_pointer
+   local.get $0
+   i32.store offset=28
+   i32.const 5620
+   local.get $0
+   i32.store
+   i32.const 5616
+   local.get $0
+   i32.const 1
+   call $~lib/rt/itcms/__link
+   global.get $~lib/memory/__stack_pointer
+   i32.const 5616
+   i32.store offset=12
+   global.get $~lib/memory/__stack_pointer
+   i32.const 5664
+   i32.store offset=28
+   i32.const 5628
+   i32.const 5664
+   i32.store
+   i32.const 5616
+   i32.const 5664
+   i32.const 1
+   call $~lib/rt/itcms/__link
+   global.get $~lib/memory/__stack_pointer
+   i32.const 5616
+   i32.store offset=12
+   global.get $~lib/memory/__stack_pointer
+   i32.const 1184
+   i32.store offset=28
+   i32.const 5616
+   call $~lib/staticarray/StaticArray<~lib/string/String>#join
+   local.set $0
+   global.get $~lib/memory/__stack_pointer
+   local.get $0
+   i32.store offset=4
+   global.get $~lib/memory/__stack_pointer
    i32.const 5696
+   i32.store offset=8
+   local.get $0
+   i32.const 5696
+   call $~lib/string/String.__eq
+   i32.eqz
+   if
+    i32.const 0
+    i32.const 1120
+    i32.const 60
+    i32.const 3
+    call $~lib/builtins/abort
+    unreachable
+   end
+   global.get $~lib/memory/__stack_pointer
+   i32.const 32
+   i32.add
+   global.set $~lib/memory/__stack_pointer
+   global.get $~lib/memory/__stack_pointer
+   i32.const 24
+   i32.sub
+   global.set $~lib/memory/__stack_pointer
+   global.get $~lib/memory/__stack_pointer
+   i32.const 5904
    i32.lt_s
    br_if $folding-inner1
    global.get $~lib/memory/__stack_pointer
@@ -3618,10 +3715,10 @@
    i32.const 24
    memory.fill
    global.get $~lib/memory/__stack_pointer
-   i32.const 5552
+   i32.const 5760
    i32.store
    global.get $~lib/memory/__stack_pointer
-   i32.const 5552
+   i32.const 5760
    i32.const 0
    call $templateliteral/RecursiveObject#constructor
    local.tee $0
@@ -3660,16 +3757,16 @@
    local.get $0
    i32.store
    global.get $~lib/memory/__stack_pointer
-   i32.const 5648
+   i32.const 5856
    i32.store offset=8
    local.get $0
-   i32.const 5648
+   i32.const 5856
    call $~lib/string/String.__eq
    i32.eqz
    if
     i32.const 0
     i32.const 1120
-    i32.const 118
+    i32.const 125
     i32.const 3
     call $~lib/builtins/abort
     unreachable
@@ -3680,8 +3777,8 @@
    global.set $~lib/memory/__stack_pointer
    return
   end
-  i32.const 38496
-  i32.const 38544
+  i32.const 38704
+  i32.const 38752
   i32.const 1
   i32.const 1
   call $~lib/builtins/abort
@@ -3786,11 +3883,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -3889,7 +3986,7 @@
      end
     end
    end
-   block $__inlined_func$~lib/util/string/compareImpl$89
+   block $__inlined_func$~lib/util/string/compareImpl$90
     loop $while-continue|1
      local.get $0
      local.tee $3
@@ -3909,7 +4006,7 @@
       local.get $4
       local.get $5
       i32.ne
-      br_if $__inlined_func$~lib/util/string/compareImpl$89
+      br_if $__inlined_func$~lib/util/string/compareImpl$90
       local.get $2
       i32.const 2
       i32.add
@@ -3947,11 +4044,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -4025,11 +4122,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -4237,11 +4334,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -4280,11 +4377,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -4497,11 +4594,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -4535,7 +4632,7 @@
   global.set $~lib/memory/__stack_pointer
   block $folding-inner0
    global.get $~lib/memory/__stack_pointer
-   i32.const 5696
+   i32.const 5904
    i32.lt_s
    br_if $folding-inner0
    global.get $~lib/memory/__stack_pointer
@@ -4562,7 +4659,7 @@
    i32.sub
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
-   i32.const 5696
+   i32.const 5904
    i32.lt_s
    br_if $folding-inner0
    global.get $~lib/memory/__stack_pointer
@@ -4589,8 +4686,8 @@
    local.get $0
    return
   end
-  i32.const 38496
-  i32.const 38544
+  i32.const 38704
+  i32.const 38752
   i32.const 1
   i32.const 1
   call $~lib/builtins/abort
@@ -4603,11 +4700,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -4664,11 +4761,11 @@
   i32.sub
   global.set $~lib/memory/__stack_pointer
   global.get $~lib/memory/__stack_pointer
-  i32.const 5696
+  i32.const 5904
   i32.lt_s
   if
-   i32.const 38496
-   i32.const 38544
+   i32.const 38704
+   i32.const 38752
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -4719,38 +4816,38 @@
   local.tee $1
   i32.store offset=12
   global.get $~lib/memory/__stack_pointer
-  i32.const 5616
+  i32.const 5824
   i32.store
   global.get $~lib/memory/__stack_pointer
   local.get $0
   i32.store offset=16
-  i32.const 5616
+  i32.const 5824
   local.get $0
   i32.store
-  i32.const 5616
+  i32.const 5824
   local.get $0
   i32.const 1
   call $~lib/rt/itcms/__link
   global.get $~lib/memory/__stack_pointer
-  i32.const 5616
+  i32.const 5824
   i32.store
   global.get $~lib/memory/__stack_pointer
   local.get $1
   i32.store offset=16
-  i32.const 5624
+  i32.const 5832
   local.get $1
   i32.store
-  i32.const 5616
+  i32.const 5824
   local.get $1
   i32.const 1
   call $~lib/rt/itcms/__link
   global.get $~lib/memory/__stack_pointer
-  i32.const 5616
+  i32.const 5824
   i32.store
   global.get $~lib/memory/__stack_pointer
   i32.const 1184
   i32.store offset=16
-  i32.const 5616
+  i32.const 5824
   call $~lib/staticarray/StaticArray<~lib/string/String>#join
   local.set $0
   global.get $~lib/memory/__stack_pointer
diff --git a/tests/compiler/templateliteral.ts b/tests/compiler/templateliteral.ts
index b6d3782712..7ced6c8454 100644
--- a/tests/compiler/templateliteral.ts
+++ b/tests/compiler/templateliteral.ts
@@ -54,6 +54,13 @@ function test_ref(): void {
 }
 test_ref();
 
+function test_null(): void {
+  var c: Ref | null = new Ref(3);
+  var d: Ref | null = null;
+  assert(`c: ${c}; d: ${d}` == "c: ref#3; d: null");
+}
+test_null();
+
 function tag(parts: TemplateStringsArray, a: i32): string {
   var raw = parts.raw;
   assert(parts.length == 2);