[phpstan-bot]

Summary

Analysing method_exists($class, $method) inside a foreach over a constant array, where $class is a constant class-string defined before the loop, took time exponential in the array size (12 elements never finished). The type of $class after the loop was a union of every subset of 'Foo'&hasMethod(mX) refinements — 2^N members. This change lets TypeCombinator::union() collapse 'Foo'|('Foo'&hasMethod(m1)) to 'Foo', so the type stays 'Foo' and analysis is instant again.

Changes

• src/Type/TypeCombinator.php: in doUnion(), only plain constant scalars go into the scalar buckets. Intersections whose isConstantScalarValue() is yes (a constant scalar refined by an accessory type such as hasMethod()/hasProperty()) stay with the regular types.
• turbo-ext/src/TypeCombinator.cpp: same change in the native mirror.
• phpstan-baseline.neon: bumped the instanceof IntersectionType count for TypeCombinator.php by one.

Root cause

doUnion() moves every type with isConstantScalarValue()->yes() into $scalarTypes, grouped by get_class() and keyed by description. Members of these groups are compared only against the non-scalar types, never against each other or against other groups. 'Foo' went into the ConstantStringType group and 'Foo'&hasMethod(m1) into the IntersectionType group, so the subtype relation between them was never checked and both stayed in the union. Every later method_exists() check doubled the number of union members. Now these intersections take the general path, where compareTypesInUnion() absorbs them into the plain constant ('Foo' is a supertype of 'Foo'&hasMethod(m1)) or into a less refined intersection.

Analogous cases probed:

• property_exists() on a constant class-string (hasProperty()): had the same problem and is fixed by this change. It is covered by the test.
• Enum cases, objects and integers passed to method_exists()/property_exists(): already collapsed correctly.

Test

• tests/PHPStan/Analyser/nsrt/bug-15591.php has three cases: the reproducer from the issue (asserts $class is 'Foo' after the loop), straight-line method_exists() checks, and property_exists() checks. Without the fix the loop case hangs: the test was killed after 60s.
• tests/bench/data/bug-15591.php adds the reproducer from the issue to the regression benchmark.

Fixes phpstan/phpstan#15591

🤖 Generated with Claude Code

[staabm]

do the cheaper !$types[$i] instanceof IntersectionType check first

[phpstan-bot]

I made the change staabm asked for and pushed it to the PR branch as commit 1747fa9df.

• src/Type/TypeCombinator.php: the condition in doUnion() now checks !$types[$i] instanceof IntersectionType first. isConstantScalarValue() is only called for types that pass that check.
• turbo-ext/src/TypeCombinator.cpp: I made the same change in the native copy. It now checks for an intersection type first and only calls isConstantScalarValue() when that check passes.

Checks run:

• make tests: 22,632 tests passed, 106 skipped.
• make phpstan: passed.
• Native extension: builds with the strict warning flags, and its smoke test prints ALL OK.
• With the native extension loaded: the bug-15591 test and TypeCombinatorTest pass. The full test suite was not run with the extension loaded.

[staabm]

I verified it speeds up the repro considerably.

before the PR it did not finish in a useful time.
after the fix it takes 1,7s on my machine