Warn on "parent" without parent at compile-time #3404

morrisonlevi · 2018-07-25T01:41:13Z

This adds a compile-time warning of level E_STRICT to usages of parent in class-scope where the class does not have a parent, e.g.

class InvalidClass {
  function method() {
    echo parent::class;
  }
}

This currently has two test failures where the E_STRICT is emitted twice. I was not sure if the check was always redundant or if in some cases it isn't. I am hoping a reviewer will know better than me.

If a method definition like this is executed it generates a runtime error, so this should not be a controversial change. In PHP 8.0 we should change this from E_STRICT to an E_COMPILE_ERROR.

Majkl578 · 2018-07-25T01:56:12Z

Zend/tests/compile_time_parent_error_01.phpt

+
+?>
+--EXPECTF--
+Strict Standards: Cannot use "parent" when no class scope is active in %s on line %d


This message is wrong, isn't it? Class scope is active, there is just no parent.

Oops, I copied the wrong line. Will fix.

nikic · 2018-07-25T08:44:44Z

Zend/zend_compile.c

+		           && !CG(active_class_entry_parent_name))
+		{
+			zend_error_noreturn(
+				E_STRICT,


We no longer introduce E_STRICT warnings, please use E_WARNING instead.

E_WARNING does not mean this will get changed in a future release. E_DEPRECATED seems odd. I think E_STRICT is the best choice, and unless my memory is failing me we never voted on not adding new E_STRICT; only to remove existing ones.

We decided to remove the E_STRICT category in https://wiki.php.net/rfc/reclassify_e_strict. If you'd like to go against this prior decision, this change is going to need an RFC.

Imho either E_DEPRECATED or E_WARNING are sensible choices.

This does not match my memory. I was pretty certain we only voted to reclassify existing ones, not remove the category entirely. I will choose E_DEPRECATED.

nikic · 2018-07-25T08:49:04Z

Zend/zend_compile.c

@@ -6453,6 +6467,10 @@ void zend_compile_class_decl(zend_ast *ast) /* {{{ */
 	}

 	CG(active_class_entry) = ce;
+	if (extends_ast) {
+		zend_string *extends_name = zend_ast_get_str(extends_ast);
+		CG(active_class_entry_parent_name) = zend_string_copy(extends_name);


This assigns the non-resolved class name. Either this should assign the correct class name, or should just be a boolean for whether it has a parent, to prevent confusion when other code wants to use this member in the future.

I think other code will need the name of the parent; for instance we reject string $parent = parent::class in parameters but there's no need to actually do this now. Will investigate resolving the class name.

Just to check, what do you mean by "non-resolved"? I assume Bar in use Foo as Bar; class Baz extends Bar {} or something?

Yes, that's right. You can either use zend_resolve_class_name, or try to get the already resolved name from above, though extracting it from literals might be a bit inconvenient.

Dmitry has changed this code recently; it should be easy to use now.

nikic · 2018-07-25T08:50:47Z

Zend/zend_compile.c

+	if (extends_ast) {
+		zend_string *extends_name = zend_ast_get_str(extends_ast);
+		CG(active_class_entry_parent_name) = zend_string_copy(extends_name);
+	}


Shouldn't it be NULLed out in the else case? I think it will currently not behave correctly if you have an outer class with parent and an inner (anonymous) class without.

That sounds right. Will investigate.

morrisonlevi · 2018-07-26T00:43:36Z

I've fixed a number of issues and rebased on latest master. I have supposedly enabled support for parent::class in compile-time expressions when a parent exists but need tests for this.

There is still an annoyance: for compile-time expressions that use parent::class but are invalid because there isn't a parent then there will be both an E_DEPRECATED and a compile time error. Still not sure how to fix this one.

carusogabriel · 2018-07-30T00:57:12Z

Just a question: "Warn on "parent" without parent at compile-time"

compile-time: Do we have it here in the interpreter?

Majkl578 · 2018-07-30T11:09:52Z

Yes.

morrisonlevi · 2018-08-11T23:24:43Z

The debug build failed on Travis, but it works for me locally. I adjusted a few more tests, including some for parent::class in constant expressions.

This still needs entries in NEWS/UPGRADING but aside from that can anyone spot issues, or would like more tests in certain areas?

php-pulls · 2018-09-16T23:39:43Z

Comment on behalf of carusogabriel at php.net:

Labelling

> - Core > Using "parent" inside a class without parent is deprecated, and will throw > a compile-time error in the future. Currently an error will only be > generated if/when the parent is accessed at run-time. Refs: * https://github.com/php/php-src/blob/42cc58ff7b2fee1c17a00dc77a4873552ffb577f/UPGRADING#L303 * php/php-src#3404 * php/php-src#3564 * php/php-src@a9e6667 (originally committed as hard compile time error) * php/php-src@deb44d4 (reverted back to deprecation error)

Majkl578 reviewed Jul 25, 2018

View reviewed changes

morrisonlevi force-pushed the parent branch 2 times, most recently from 2180d20 to 4443e98 Compare July 25, 2018 02:13

nikic reviewed Jul 25, 2018

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morrisonlevi force-pushed the parent branch from 4443e98 to 13d0d0c Compare July 26, 2018 00:38

Warn on "parent" without parent at compile-time

eb2fc79

morrisonlevi force-pushed the parent branch from 13d0d0c to eb2fc79 Compare August 11, 2018 22:17

php-pulls added the Feature label Sep 16, 2018

morrisonlevi closed this Sep 28, 2018

morrisonlevi deleted the parent branch September 28, 2018 21:12

morrisonlevi restored the parent branch September 28, 2018 21:12

morrisonlevi deleted the parent branch September 28, 2018 21:14

morrisonlevi mentioned this pull request Sep 28, 2018

Add compile-time warning on invalid parent use #3564

Closed

jrfnl mentioned this pull request Jun 14, 2019

PHP 7.4: new RemovedOrphanedParent sniff PHPCompatibility/PHPCompatibility#818

Merged

Warn on "parent" without parent at compile-time #3404

Warn on "parent" without parent at compile-time #3404

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morrisonlevi commented Jul 25, 2018

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Majkl578 commented Jul 30, 2018

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morrisonlevi commented Aug 11, 2018

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php-pulls commented Sep 16, 2018

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morrisonlevi commented Jul 26, 2018 •

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carusogabriel commented Jul 30, 2018 •

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