resolve classes from @param phpdoc (#1015)

Purpose: when a class occurs only in @param and is actually never created, 
resolve it in CollectRequiredPass.
Previously, @param weren't analyzed there, because phpdocs haven't been 
parsed up to that execution point, and I didn't want to perform parsing twice.

compiler/pipes/collect-required-and-classes.cpp

@@ -126,9 +126,23 @@ class CollectRequiredPass final : public FunctionPassBase {
     }
   }
 
-  // Collect classes only from type hints in PHP code, as phpdocs @param/@return haven't been parsed up to this execution point.
-  // TODO: shall we fix this?
+  // Collect classes from @param and type hints
   inline void require_all_classes_from_func_declaration(FunctionPtr f) {
+    // note, that @param has't been parsed up to this execution point, so parsing is done twice
+    // (here and later in ParseAndApplyPhpdocF), it's very ugly, since parsing is quite a heavy operation
+    // ideally, types in phpdoc should be parsed once in gentree, but actually,
+    // vkcom has so much syntax-invalid phpdocs, that it's unavailable
+    // (that "invalid" functions aren't reachable in fact, they just exist in a dead codebase,
+    //  so their phpdocs aren't analyzed later, but trying to parse them in gentree leads to 10k errors)
+    if (f->phpdoc && !f->is_lambda()) {
+      for (const PhpDocTag &tag : f->phpdoc->tags) {
+        if (tag.type == PhpDocType::param) {
+          if (auto tag_parsed = tag.value_as_type_and_var_name(current_function, current_function->genericTs)) {
+            require_all_classes_in_phpdoc_type(tag_parsed.type_hint);
+          }
+        }
+      }
+    }
     for (const auto &p: f->get_params()) {
       if (p.as<op_func_param>()->type_hint) {
         require_all_classes_in_phpdoc_type(p.as<op_func_param>()->type_hint);

tests/phpt/cl/030_resolve_from_phpdoc.php

@@ -26,6 +26,14 @@ function f2() {
     else echo "a null\n";
 }
 
+/**
+ * @param ?\Classes\Z3Infer $b
+ */
+function f3($b) {
+  if ($b) $b->thisHasInfer(1,2);
+}
+
 f1(null);
 f2();
+f3(null);
 (new BB)->f();