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Fix 15042: ValueFlow: conditionally reassigned value should not be known - #8899

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pfultz2 wants to merge 7 commits into
cppcheck-opensource:mainfrom
pfultz2:programmmemory-multi-values
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Fix 15042: ValueFlow: conditionally reassigned value should not be known#8899
pfultz2 wants to merge 7 commits into
cppcheck-opensource:mainfrom
pfultz2:programmmemory-multi-values

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@pfultz2 pfultz2 commented Sep 27, 2026

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This refactors ProgramMemory so it can store a list of values.

A condition such as x > 3 was recorded as the possible value 4 with a lower bound, and the executor then used it as if x were exactly 4. Nested conditions were decided wrongly, so branches were skipped and values leaked past or were lost before them. This what lead to the FP in 15042.

Now it can understand these constraints better. As new values are added, it is resolved similar to Token::addValue.

github-advanced-security[bot]
github-advanced-security Bot found potential problems Sep 27, 2026
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Comment thread lib/programmemory.cpp
// Shifts: calculate() rejects a negative or too large shift and a negative value
bool error = false;
result = calculate(op, edge, k, &error);
if (!rangeIsLhs || error || (op == "<<" && (result >> k) != edge))
Comment thread lib/programmemory.cpp
// Shifts: calculate() rejects a negative or too large shift and a negative value
bool error = false;
result = calculate(op, edge, k, &error);
if (!rangeIsLhs || error || (op == "<<" && (result >> k) != edge))
Comment thread lib/programmemory.cpp
// known value and does not depend on a tracked value
const Values* getStoredValues(const Token* expr) const
{
if (expr->exprId() == 0)
Comment thread lib/programmemory.cpp
const ValueFlow::Value& v = utils::as_const(*pm).at(expr->exprId());
if (v.isIntValue())
return v;
if (const ValueFlow::Value* v = pm->getValue(expr->exprId(), /*impossible*/ true)) {
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