Random bug fixes (#542)

* Document bug comparison empty statements
The operators `<=` and `>=` should be treated as empty.
They are currently treated as assignments.

* Fix false negative, `<=` and `>=` in NoEmptyStatementsLinter

* Document bug NodeList::getChildrenOfItemsOfType() does not refine

* Fix type refinement of NodeList::getChildrenOfItemsOfType<T>()

* Add NodeList::getChildrenOfItemsByType<T>()
This completes this list:
 - Node->getChildrenOfType<T>()
 - Node->getDescendantsOfType<T>()
 - Node->getFirstDescendantOfType<T>()
 - NodeList->getChildrenOfItemsByType<T>()

* Remove reference in comment to createMaybeEmptyList
This function does not exist anymore.

* Post commit formatting

* Lint clean

* Lint clean (with HHClientLinter)

* Post commit formatting

* One (last) lint error from HHClientLinter

* Demonstrate the `() ==> constant` can not be parsed

* Regenerate codegen, allowing constants as lambda bodies
The Package* classes were deleted by codegen.
I have ignored these deletions for backwards compat.

* Limit semaphore to cpu count
I don't got no 32 hardware threads

* Fix lint error in syntax example

Author: lexidor

codegen/inferred_relationships.hack

@@ -131,7 +131,7 @@ final class NoEmptyStatementsLinter extends AutoFixingASTLinter {
   /**
    * Returns whether the given token is an assignment operator.
    *
-   * This list is all the types returned from ExpressionStatement::getOperator
+   * This list is all the types returned from BinaryExpression::getOperator
    * that include "Equal" and are not comparison operators (==, >=, etc.);
    */
   private function isAssignmentOperator(Token $op): bool {
@@ -140,9 +140,7 @@ final class NoEmptyStatementsLinter extends AutoFixingASTLinter {
       $op is CaratEqualToken ||
       $op is DotEqualToken ||
       $op is EqualToken ||
-      $op is GreaterThanEqualToken ||
       $op is GreaterThanGreaterThanEqualToken ||
-      $op is LessThanEqualToken ||
       $op is LessThanLessThanEqualToken ||
       $op is MinusEqualToken ||
       $op is PercentEqualToken ||

codegen/syntax/LambdaExpression.hack

@@ -55,8 +55,8 @@ final class UnusedUseClauseLinter extends AutoFixingASTLinter {
           $as = $name->getText();
         } else {
           invariant($name is QualifiedName, 'Unhandled name type');
-          $as = $name->getParts()->getChildrenOfItemsOfType(NameToken::class)
-            |> (C\lastx($$) as nonnull)->getText();
+          $as = $name->getParts()->getChildrenOfItemsByType<NameToken>()
+            |> C\lastx($$)->getText();
         }
       }
       if ($kind is NamespaceToken) {

codegen/syntax/QualifiedName.hack

@@ -55,10 +55,8 @@ final class UseStatementWithoutKindLinter extends AutoFixingASTLinter {
         }
         $name = $clause->getName();
         if ($name is QualifiedName) {
-          return (
-            C\lastx(
-              $name->getParts()->getChildrenOfItemsOfType(NameToken::class),
-            ) as nonnull
+          return C\lastx(
+            $name->getParts()->getChildrenOfItemsByType<NameToken>(),
           )->getText();
         }
         invariant(
@@ -73,10 +71,8 @@ final class UseStatementWithoutKindLinter extends AutoFixingASTLinter {
     // We need to look at the full file to figure out if this should be a
     // `use type`, or `use namespace`
     $used = $this->getUnresolvedReferencedNames();
-    $used_as_ns = C\any(
-      $names,
-      $name ==> C\contains($used['namespaces'], $name),
-    );
+    $used_as_ns =
+      C\any($names, $name ==> C\contains($used['namespaces'], $name));
     $used_as_type = C\any($names, $name ==> C\contains($used['types'], $name));
 
     $leading = $node->getClauses()->getFirstTokenx()->getLeadingWhitespace();
@@ -94,8 +90,7 @@ final class UseStatementWithoutKindLinter extends AutoFixingASTLinter {
   }
 
   <<__Memoize>>
-  private function getUnresolvedReferencedNames(
-  ): shape(
+  private function getUnresolvedReferencedNames(): shape(
     'namespaces' => keyset<string>,
     'types' => keyset<string>,
     'functions' => keyset<string>,

codegen/tokens/NameToken.hack

@@ -523,7 +523,7 @@ final class HSLMigration extends BaseMigration {
         }
         $found_prefix = true;
         foreach ($parts as $i => $token) {
-          if ($token?->getText() === $search[$i]) {
+          if ($token->getText() === $search[$i]) {
             continue;
           }
           $found_prefix = false;
@@ -569,14 +569,14 @@ final class HSLMigration extends BaseMigration {
             }
 
             foreach ($parts as $i => $token) {
-              if ($i < 2 && $token?->getText() !== $search[$i]) {
+              if ($i < 2 && $token->getText() !== $search[$i]) {
                 break;
               }
 
               if ($i === 2) {
                 // we found an HH\Lib\* use statement, add the node and suffix
                 $nodes[] = $decl;
-                $ns = HslNamespace::coerce($token?->getText());
+                $ns = HslNamespace::coerce($token->getText());
                 if ($ns !== null) {
                   $suffixes[] = $ns;
                 }

src/Linters/NoEmptyStatementsLinter.hack

@@ -217,6 +217,9 @@ abstract class CodegenBase {
       HHAST\ILambdaBody::class => keyset[
         HHAST\IExpression::class,
         HHAST\CompoundStatement::class,
+        // Constants are not wrapped in a name expression on the RHS of `==>`.
+        HHAST\NameToken::class,
+        HHAST\QualifiedName::class,
       ],
       HHAST\ILambdaSignature::class => keyset[
         HHAST\VariableExpression::class,
@@ -239,8 +242,6 @@ abstract class CodegenBase {
         HHAST\ParameterDeclaration::class,
         HHAST\PropertyDeclaration::class,
         HHAST\LambdaExpression::class,
-        // HHAST\Php7AnonymousFunction::class : not valid in hack. No attributes
-        // if not hack
       ],
       HHAST\INameishNode::class => keyset[
         HHAST\NameToken::class,

src/Linters/UnusedUseClauseLinter.hack

@@ -60,7 +60,7 @@ final class CodegenRelations extends CodegenBase {
 
     $relationships = new Ref(dict[]);
     $queue = new Async\Semaphore(
-      /* limit = */ 32,
+      \cpu_get_count(),
       async $file ==> {
         try {
           $links = await $this->getRelationsInFileAsync($file);