Preserve reflector-derived column types when AST narrowing yields ErrorType

[ArtemGoutsoul]

Preserve reflector-derived column types when AST narrowing yields ErrorType

Issue

With utilizeSqlAst(true) + defaultFetchMode(FETCH_TYPE_ASSOC) on PHPStan 2.2+, any SELECT that references columns through a table alias collapses every column's value type to *ERROR*:

// service_group(service_group_id int unsigned, name varchar(45))

SELECT service_group_id, name FROM service_group
//  array{service_group_id: int<0, 4294967295>, name: string}        ✅

SELECT sg.service_group_id, sg.name FROM service_group sg
//  array{service_group_id: *ERROR*, name: *ERROR*}                  ❌

Worked on PHPStan 2.1; regressed in 2.2.

Why

In ParserInference::narrowResultType(), per column:

1. $valueType = $resultType->getOffsetValueType(ConstantIntegerType($i)) — but the FETCH_TYPE_ASSOC row shape from the reflector is string-keyed only. PHPStan 2.2 changed missing-offset reads to return ErrorType (previously benign).
2. $queryScope->getType($expression) is supposed to refine it. For unqualified columns it returns the real column type and overwrites the ErrorType. For alias-qualified columns (t.col) resolveExpression() has no branch for qualified identifiers and falls through to MixedType, so the guard ! $type instanceof MixedType skips the assignment.
3. $valueType (still ErrorType) is then written over the correct reflector-derived type under the column-name key.

Fix

After the QueryScope refinement step, skip the column when $valueType is still ErrorType — there is no information to add, so leave the reflector's type untouched.

$type = $queryScope->getType($expression);
if (! $type instanceof MixedType) {
    $valueType = $type;
}

if ($valueType instanceof ErrorType) {
    continue;
}

Minimal, targeted: only changes behavior on the previously-broken path. A follow-up could teach QueryScope::resolveExpression() to resolve qualified identifiers and restore full AST narrowing (JOIN/WHERE nullability) for aliased columns, but that's a larger change.

Test

Added tests/default/ParserInferenceTest.php — a plain PHPUnit test that drives ParserInference::narrowResultType() directly with a synthetic assoc-only ConstantArrayType, covering both unqualified and t.col-qualified queries. Fails without the patch (*ERROR* in the alias-qualified case), passes with it.

[staabm]

could we check $resultType->hasOffsetValueType() before we call $resultType->getOffsetValueType instead?

[ArtemGoutsoul]

Good call — switched to a hasOffsetValueType() guard before the read. Same observable behavior, but no longer depends on the missing-offset return type. Matches the pattern used by the setOffsetValueType() calls below.

[staabm]

thank you!