Allow void ternary expressions

src/compiler.ts

@@ -9212,20 +9212,32 @@ export class Compiler extends DiagnosticEmitter {
     var ifElseExpr = this.compileExpression(ifElse, ctxType == Type.auto ? ifThenType : ctxType);
     var ifElseType = this.currentType;
 
-    var commonType = Type.commonDenominator(ifThenType, ifElseType, false);
-    if (!commonType) {
-      this.error(
-        DiagnosticCode.Type_0_is_not_assignable_to_type_1,
-        ifElse.range, ifElseType.toString(), ifThenType.toString()
-      );
-      this.currentType = ctxType;
-      return module.unreachable();
+    if (ctxType == Type.void) { // values, including type mismatch, are irrelevant
+      if (ifThenType != Type.void) {
+        ifThenExpr = module.drop(ifThenExpr);
+        ifThenType = Type.void;
+      }
+      if (ifElseType != Type.void) {
+        ifElseExpr = module.drop(ifElseExpr);
+        ifElseType = Type.void;
+      }
+      this.currentType = Type.void;
+    } else {
+      let commonType = Type.commonDenominator(ifThenType, ifElseType, false);
+      if (!commonType) {
+        this.error(
+          DiagnosticCode.Type_0_is_not_assignable_to_type_1,
+          ifElse.range, ifElseType.toString(), ifThenType.toString()
+        );
+        this.currentType = ctxType;
+        return module.unreachable();
+      }
+      ifThenExpr = this.convertExpression(ifThenExpr, ifThenType, commonType, false, ifThen);
+      ifThenType = commonType;
+      ifElseExpr = this.convertExpression(ifElseExpr, ifElseType, commonType, false, ifElse);
+      ifElseType = commonType;
+      this.currentType = commonType;
     }
-    ifThenExpr = this.convertExpression(ifThenExpr, ifThenType, commonType, false, ifThen);
-    ifThenType = commonType;
-    ifElseExpr = this.convertExpression(ifElseExpr, ifElseType, commonType, false, ifElse);
-    ifElseType = commonType;
-    this.currentType = commonType;
 
     ifThenFlow.freeScopedLocals();
     ifElseFlow.freeScopedLocals();

tests/compiler/ternary.optimized.wat

@@ -1,12 +1,91 @@
 (module
+ (type $none_=>_none (func))
  (type $i32_i32_i32_=>_i32 (func (param i32 i32 i32) (result i32)))
- (memory $0 0)
+ (type $i32_=>_none (func (param i32)))
+ (type $i32_i32_i32_i32_=>_none (func (param i32 i32 i32 i32)))
+ (type $i32_i32_=>_none (func (param i32 i32)))
+ (import "env" "abort" (func $~lib/builtins/abort (param i32 i32 i32 i32)))
+ (global $~lib/memory/__stack_pointer (mut i32) (i32.const 17452))
+ (memory $0 1)
+ (data (i32.const 1036) "\1c")
+ (data (i32.const 1048) "\01\00\00\00\02\00\00\00a")
+ (table $0 1 funcref)
  (export "test" (func $ternary/test))
+ (export "testDropWithTypeMismatch" (func $ternary/testDropWithTypeMismatch))
  (export "memory" (memory $0))
+ (export "testVoidInclTypeMismatch" (func $export:ternary/testVoidInclTypeMismatch))
  (func $ternary/test (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
   local.get $1
   local.get $2
   local.get $0
   select
  )
+ (func $ternary/testDropWithTypeMismatch (param $0 i32)
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.sub
+  global.set $~lib/memory/__stack_pointer
+  global.get $~lib/memory/__stack_pointer
+  i32.const 1068
+  i32.lt_s
+  if
+   i32.const 17472
+   i32.const 17520
+   i32.const 1
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
+  global.get $~lib/memory/__stack_pointer
+  local.tee $0
+  i32.const 0
+  i32.store
+  local.get $0
+  i32.const 1056
+  i32.store
+  local.get $0
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+ )
+ (func $export:ternary/testVoidInclTypeMismatch (param $0 i32) (param $1 i32)
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.sub
+  global.set $~lib/memory/__stack_pointer
+  global.get $~lib/memory/__stack_pointer
+  i32.const 1068
+  i32.lt_s
+  if
+   i32.const 17472
+   i32.const 17520
+   i32.const 1
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
+  global.get $~lib/memory/__stack_pointer
+  local.get $1
+  i32.store
+  local.get $1
+  i32.load
+  call_indirect $0 (type $none_=>_none)
+  local.get $0
+  if
+   local.get $1
+   i32.load
+   call_indirect $0 (type $none_=>_none)
+  end
+  local.get $0
+  i32.eqz
+  if
+   local.get $1
+   i32.load
+   call_indirect $0 (type $none_=>_none)
+  end
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+ )
 )

tests/compiler/ternary.ts

@@ -11,3 +11,15 @@ a = (0 ? unreachable() : 1) ? 1 : unreachable();
 export function test(x: i32, y: i32, z: i32): i32 {
   return x ? y : z;
 }
+
+export function testDropWithTypeMismatch(cond: bool): void {
+  var x = 1;
+  var y = "a";
+  cond ? x : y;
+}
+
+export function testVoidInclTypeMismatch(cond: bool, nop: () => void): void {
+  cond ? nop() : nop();
+  cond ? nop() : true;
+  cond ? true : nop();
+}

tests/compiler/ternary.untouched.wat

@@ -1,15 +1,23 @@
 (module
  (type $none_=>_none (func))
+ (type $i32_i32_=>_none (func (param i32 i32)))
  (type $i32_i32_i32_=>_i32 (func (param i32 i32 i32) (result i32)))
+ (type $i32_=>_none (func (param i32)))
+ (type $i32_i32_i32_i32_=>_none (func (param i32 i32 i32 i32)))
+ (import "env" "abort" (func $~lib/builtins/abort (param i32 i32 i32 i32)))
  (global $ternary/a (mut i32) (i32.const 0))
- (global $~lib/memory/__data_end i32 (i32.const 8))
- (global $~lib/memory/__stack_pointer (mut i32) (i32.const 16392))
- (global $~lib/memory/__heap_base i32 (i32.const 16392))
- (memory $0 0)
+ (global $~argumentsLength (mut i32) (i32.const 0))
+ (global $~lib/memory/__data_end i32 (i32.const 44))
+ (global $~lib/memory/__stack_pointer (mut i32) (i32.const 16428))
+ (global $~lib/memory/__heap_base i32 (i32.const 16428))
+ (memory $0 1)
+ (data (i32.const 12) "\1c\00\00\00\00\00\00\00\00\00\00\00\01\00\00\00\02\00\00\00a\00\00\00\00\00\00\00\00\00\00\00")
  (table $0 1 funcref)
  (elem $0 (i32.const 1))
  (export "test" (func $ternary/test))
+ (export "testDropWithTypeMismatch" (func $ternary/testDropWithTypeMismatch))
  (export "memory" (memory $0))
+ (export "testVoidInclTypeMismatch" (func $export:ternary/testVoidInclTypeMismatch))
  (start $~start)
  (func $start:ternary
   i32.const 1
@@ -33,7 +41,105 @@
    local.get $2
   end
  )
+ (func $ternary/testDropWithTypeMismatch (param $0 i32)
+  (local $1 i32)
+  (local $2 i32)
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.sub
+  global.set $~lib/memory/__stack_pointer
+  call $~stack_check
+  global.get $~lib/memory/__stack_pointer
+  i32.const 0
+  i32.store
+  i32.const 1
+  local.set $1
+  global.get $~lib/memory/__stack_pointer
+  i32.const 32
+  local.tee $2
+  i32.store
+  local.get $0
+  if
+   local.get $1
+   drop
+  else
+   local.get $2
+   drop
+  end
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+ )
+ (func $ternary/testVoidInclTypeMismatch (param $0 i32) (param $1 i32)
+  local.get $0
+  if
+   i32.const 0
+   global.set $~argumentsLength
+   local.get $1
+   i32.load
+   call_indirect $0 (type $none_=>_none)
+  else
+   i32.const 0
+   global.set $~argumentsLength
+   local.get $1
+   i32.load
+   call_indirect $0 (type $none_=>_none)
+  end
+  local.get $0
+  if
+   i32.const 0
+   global.set $~argumentsLength
+   local.get $1
+   i32.load
+   call_indirect $0 (type $none_=>_none)
+  else
+   i32.const 1
+   drop
+  end
+  local.get $0
+  if
+   i32.const 1
+   drop
+  else
+   i32.const 0
+   global.set $~argumentsLength
+   local.get $1
+   i32.load
+   call_indirect $0 (type $none_=>_none)
+  end
+ )
  (func $~start
   call $start:ternary
  )
+ (func $~stack_check
+  global.get $~lib/memory/__stack_pointer
+  global.get $~lib/memory/__data_end
+  i32.lt_s
+  if
+   i32.const 16448
+   i32.const 16496
+   i32.const 1
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
+ )
+ (func $export:ternary/testVoidInclTypeMismatch (param $0 i32) (param $1 i32)
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.sub
+  global.set $~lib/memory/__stack_pointer
+  call $~stack_check
+  global.get $~lib/memory/__stack_pointer
+  local.get $1
+  i32.store
+  local.get $0
+  local.get $1
+  call $ternary/testVoidInclTypeMismatch
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+ )
 )