Static analysis: Using $this in a static method should show an error

[MaartenStaa]

Closes #476

Two scenarios produce errors, either $this is used in a static method (as described in the issue), or when it's used outside of a class method altogether, e.g.:

<?php class A { public static function foo() { return $this; // error here } public function bar() { return $this; // no error here (of course) } } function foo() { return $this; // error here } echo $this; // error here

[codecov]

Codecov Report

Merging #528 into master will increase coverage by 0.47%.
The diff coverage is 100%.

@@ Coverage Diff @@ ## master #528 +/- ## ============================================ + Coverage 78.91% 79.38% +0.47%  - Complexity 832 837 +5  ============================================ Files 56 56 Lines 1968 1979 +11 ============================================ + Hits 1553 1571 +18  + Misses 415 408 -7

Impacted Files	Coverage Δ	Complexity Δ
src/TreeAnalyzer.php	94.64% <100%> (+0.58%)	54 <0> (+5)	⬆️
src/DefinitionResolver.php	84.05% <0%> (+1.12%)	302% <0%> (ø)	⬇️
src/Cache/FileSystemCache.php	27.27% <0%> (+4.54%)	8% <0%> (ø)	⬇️

[felixfbecker]

Could you add a test for this?

[jens1o]

Should this be included in the parser instead?

[MaartenStaa]

@jens1o see #476, I asked the same question.

edit: as php -l itself does not produce a parse error either for this, it makes sense that the parser would not produce an error diagnostic.

[felixfbecker]

This is awesome