Incorrect "negated boolean expression is always false" with boolean comparison of variadic parameter and "treatPhpDocTypesAsCertain: false" #6393
Description
Bug report
Reproduced in latest PHPStan v1.4.1.
When a function has a variadic parameter, that parameter is typed as an object, and treatPhpDocTypesAsCertain: false is used, PHPStan seems to incorrectly believe that the array created from the variadic parameter values will be non-empty.
Code snippet that reproduces the problem
Playground test case
https://phpstan.org/r/9c91108d-fdf7-44a0-8710-4549a756684d
Expected output
No error should be thrown on line 10. It is valid to call sayHello() with no parameters, and then an empty $people array would be created.
If you enable the "Treat PHPDoc types as certain" flag, the correct behaviour is used.
In addition, if you change the type of $people to a scalar type, the correct behaviour is used.
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