Fewer varEnvs in generators

If the original function has a variable that the generator does not,
we create a varenv. Its not clear that that should ever happen, but
it *was* happening because:

 - closures get a magic variable called 0Closure, but generators
from closures did not.

 - unused parameters didnt get put into the variable table, so
generators with unused parameters got a varenv

hphp/compiler/analysis/emitter.cpp

@@ -5319,15 +5319,17 @@ void EmitterVisitor::emitPostponedMeths() {
 
     m_curFunc = fe;
 
-    if (fe->isClosureBody()) {
+    if (fe->isClosureBody() || fe->isGeneratorFromClosure()) {
       // We are going to keep the closure as the first local
       fe->allocVarId(StringData::GetStaticString("0Closure"));
 
-      ClosureUseVarVec* useVars = p.m_closureUseVars;
-      for (auto& useVar : *useVars) {
-        // These are all locals. I want them right after the params so I don't
-        // have to keep track of which one goes where at runtime.
-        fe->allocVarId(useVar.first);
+      if (fe->isClosureBody()) {
+        ClosureUseVarVec* useVars = p.m_closureUseVars;
+        for (auto& useVar : *useVars) {
+          // These are all locals. I want them right after the params so I don't
+          // have to keep track of which one goes where at runtime.
+          fe->allocVarId(useVar.first);
+        }
       }
     }
 

hphp/compiler/statement/method_statement.cpp

@@ -14,8 +14,6 @@
    +----------------------------------------------------------------------+
 */
 
-#include "hphp/runtime/base/complex_types.h"
-
 #include "hphp/compiler/statement/method_statement.h"
 #include "hphp/compiler/statement/return_statement.h"
 #include "hphp/compiler/statement/statement_list.h"
@@ -47,6 +45,8 @@
 #include "hphp/compiler/builtin_symbols.h"
 #include "hphp/compiler/analysis/alias_manager.h"
 
+#include "hphp/runtime/base/complex_types.h"
+
 #include "hphp/util/parser/parser.h"
 #include "hphp/util/util.h"
 
@@ -389,8 +389,7 @@ void MethodStatement::analyzeProgram(AnalysisResultPtr ar) {
       if (ExpressionListPtr params = orig->getParams()) {
         for (int i = 0; i < params->getCount(); ++i) {
           auto param = dynamic_pointer_cast<ParameterExpression>((*params)[i]);
-          Symbol *gp = variables->addDeclaredSymbol(
-            param->getName(), ConstructPtr());
+          Symbol *gp = variables->addDeclaredSymbol(param->getName(), param);
           gp->setGeneratorParameter();
           if (param->isRef()) {
             gp->setRefGeneratorParameter();