fix misleading compile error on multi-assignment

multiassignment causes compiler error later on code that has no errors

fix #1699

Author: petersalomonsen

NOTICE

@@ -33,6 +33,7 @@ under the licensing terms detailed in LICENSE:
 * Piotr Oleś <piotrek.oles@gmail.com>
 * Saúl Cabrera <saulecabrera@gmail.com>
 * Chance Snow <git@chancesnow.me>
+* Peter Salomonsen <petersalomonsen@runbox.com>
 
 Portions of this software are derived from third-party works licensed under
 the following terms:

src/flow.ts

@@ -327,7 +327,8 @@ export class Flow {
       }
       local = parentFunction.addLocal(type);
     } else {
-      if (temps !== null && temps.length > 0) {
+      if (temps !== null && temps.length > 0
+          && temps[temps.length-1].type === type) {
         local = assert(temps.pop());
         local.type = type;
         local.flags = CommonFlags.NONE;

tests/compiler/abi.untouched.wat

@@ -131,8 +131,8 @@
   end
   i32.const 2
   i32.ctz
-  local.set $0
-  local.get $0
+  local.set $1
+  local.get $1
   i32.const 0
   i32.ne
   i32.eqz
@@ -146,8 +146,8 @@
   end
   i32.const 1
   i32.clz
-  local.set $0
-  local.get $0
+  local.set $1
+  local.get $1
   i32.const 0
   i32.ne
   i32.eqz
@@ -161,8 +161,8 @@
   end
   i32.const 2
   i32.ctz
-  local.set $1
-  local.get $1
+  local.set $0
+  local.get $0
   i32.eqz
   if
    i32.const 0
@@ -174,8 +174,8 @@
   end
   i32.const 1
   i32.clz
-  local.set $1
-  local.get $1
+  local.set $0
+  local.get $0
   i32.eqz
   if
    i32.const 0

tests/compiler/assert-nonnull.untouched.wat

@@ -128,6 +128,7 @@
  (func $assert-nonnull/testAll (param $0 i32) (result i32)
   (local $1 i32)
   (local $2 i32)
+  (local $3 i32)
   global.get $~lib/memory/__stack_pointer
   i32.const 8
   i32.sub
@@ -150,18 +151,18 @@
    call $~lib/builtins/abort
    unreachable
   end
-  local.set $2
+  local.set $3
   global.get $~lib/memory/__stack_pointer
-  local.get $2
+  local.get $3
   i32.store
-  local.get $2
+  local.get $3
   i32.const 0
   call $~lib/array/Array<assert-nonnull/Foo|null>#__get
-  local.tee $1
+  local.tee $2
   i32.store offset=4
-  local.get $1
+  local.get $2
   if (result i32)
-   local.get $1
+   local.get $2
   else
    i32.const 32
    i32.const 96
@@ -171,11 +172,11 @@
    unreachable
   end
   i32.load
-  local.tee $1
+  local.tee $2
   i32.store offset=4
-  local.get $1
+  local.get $2
   if (result i32)
-   local.get $1
+   local.get $2
   else
    i32.const 32
    i32.const 96
@@ -184,16 +185,17 @@
    call $~lib/builtins/abort
    unreachable
   end
-  local.set $2
+  local.set $3
   global.get $~lib/memory/__stack_pointer
   i32.const 8
   i32.add
   global.set $~lib/memory/__stack_pointer
-  local.get $2
+  local.get $3
  )
  (func $assert-nonnull/testAll2 (param $0 i32) (result i32)
   (local $1 i32)
   (local $2 i32)
+  (local $3 i32)
   global.get $~lib/memory/__stack_pointer
   i32.const 8
   i32.sub
@@ -216,18 +218,18 @@
    call $~lib/builtins/abort
    unreachable
   end
-  local.set $2
+  local.set $3
   global.get $~lib/memory/__stack_pointer
-  local.get $2
+  local.get $3
   i32.store
-  local.get $2
+  local.get $3
   i32.const 0
   call $~lib/array/Array<assert-nonnull/Foo|null>#__get
-  local.tee $1
+  local.tee $2
   i32.store offset=4
-  local.get $1
+  local.get $2
   if (result i32)
-   local.get $1
+   local.get $2
   else
    i32.const 32
    i32.const 96
@@ -237,11 +239,11 @@
    unreachable
   end
   i32.load
-  local.tee $1
+  local.tee $2
   i32.store offset=4
-  local.get $1
+  local.get $2
   if (result i32)
-   local.get $1
+   local.get $2
   else
    i32.const 32
    i32.const 96
@@ -250,12 +252,12 @@
    call $~lib/builtins/abort
    unreachable
   end
-  local.set $2
+  local.set $3
   global.get $~lib/memory/__stack_pointer
   i32.const 8
   i32.add
   global.set $~lib/memory/__stack_pointer
-  local.get $2
+  local.get $3
  )
  (func $assert-nonnull/testProp (param $0 i32) (result i32)
   (local $1 i32)