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Compare ternary arm values, not their truthiness, in exact narrowing contexts - #6580
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…contexts `(cond ? if : else) !== false` was narrowed through the boolean rewrite `(cond && if) || (!cond && else)` with the `!== false` context passed to the arms, which reads `0 !== false` as `0` being truthy. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LuUxEfBoMtVfZmJsUxA85s
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The ternary exact-context narrowing (#6580) is ported onto the composed (cond && if) || (!cond && else) narrowing: in an exact context the arms become `arm === true` / `arm !== false` (...) operands of a truthy decomposition, narrowed like the comparison node would be, with a native mirror in turbo-ext/src/TernaryHandler.cpp. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LuUxEfBoMtVfZmJsUxA85s
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TernaryHandler::specifyTypes()narrowscond ? if : elsethrough the boolean rewrite(cond && if) || (!cond && else)and passes the context down unchanged. That only holds for truthy/falsey contexts. For the exact contexts (=== true,=== false,!== true,!== false) the arms became boolean operands, so e.g.(!$a ? f() : 0) !== falseread0 !== falseas "0is truthy", ruled out the$aarm and narrowed$atofalse.The assign-time conditional expressions (
if $b is int then $a is false) are built from exactly this narrowing, so the wrong type then leaked into later branches.Exact contexts now compare each arm to the constant instead (
(cond && if !== false) || (!cond && else !== false), evaluated in a truthy context), so only the condition is treated by truthiness. Side effect:=== false/=== trueon a ternary now narrows more precisely, e.g.(!$a ? f() : 0) === falsegives$aasfalse.Closes phpstan/phpstan#15307
Closes phpstan/phpstan#15226
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