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Report overlappingInnerCondition errors #8448

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37deb79
Report overlapping inner conditions as identicalInnerCondition
francois-berder Apr 1, 2026
8dad4aa
fixup! Report overlapping inner conditions as identicalInnerCondition
francois-berder Apr 17, 2026
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20 changes: 19 additions & 1 deletion lib/checkcondition.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -602,7 +602,7 @@ void CheckCondition::oppositeElseIfConditionError(const Token *ifCond, const Tok

//---------------------------------------------------------------------------
// - Opposite inner conditions => always false
// - (TODO) Same/Overlapping inner condition => always true
// - Same/Overlapping inner condition => always true
// - same condition after early exit => always false
//---------------------------------------------------------------------------

Expand Down Expand Up @@ -759,6 +759,8 @@ void CheckCondition::multiCondition2()
oppositeInnerConditionError(firstCondition, cond2, errorPath);
} else if (!isReturnVar && isSameExpression(true, firstCondition, cond2, *mSettings, true, true, &errorPath)) {
identicalInnerConditionError(firstCondition, cond2, errorPath);
} else if (!isReturnVar && isOverlappingCond(cond2, firstCondition, true)) {
overlappingInnerConditionError(firstCondition, cond2, errorPath);
}
}
return ChildrenToVisit::none;
Expand Down Expand Up @@ -879,6 +881,21 @@ void CheckCondition::oppositeInnerConditionError(const Token *tok1, const Token*
reportError(std::move(errorPath), Severity::warning, "oppositeInnerCondition", msg, CWE398, Certainty::normal);
}

void CheckCondition::overlappingInnerConditionError(const Token *tok1, const Token* tok2, ErrorPath errorPath)
{
if (diag(tok1, tok2))
return;
const std::string s1(tok1 ? tok1->expressionString() : "x");
const std::string s2(tok2 ? tok2->expressionString() : "x");
const std::string innerSmt = innerSmtString(tok2);
errorPath.emplace_back(tok1, "outer condition: " + s1);
errorPath.emplace_back(tok2, "overlapping inner condition: " + s2);

const std::string msg("Overlapping inner '" + innerSmt + "' condition is always true.\n"
"Overlapping inner '" + innerSmt + "' condition is always true (outer condition is '" + s1 + "' and inner condition is '" + s2 + "').");
reportError(std::move(errorPath), Severity::warning, "overlappingInnerCondition", msg, CWE398, Certainty::normal);
}

void CheckCondition::identicalInnerConditionError(const Token *tok1, const Token* tok2, ErrorPath errorPath)
{
if (diag(tok1, tok2))
Expand Down Expand Up @@ -2111,6 +2128,7 @@ void CheckCondition::getErrorMessages(ErrorLogger *errorLogger, const Settings *
c.comparisonError(nullptr, "&", 6, "==", 1, false);
c.duplicateConditionError(nullptr, nullptr, ErrorPath{});
c.overlappingElseIfConditionError(nullptr, 1);
c.overlappingInnerConditionError(nullptr, nullptr, ErrorPath());
c.mismatchingBitAndError(nullptr, 0xf0, nullptr, 1);
c.oppositeInnerConditionError(nullptr, nullptr, ErrorPath{});
c.identicalInnerConditionError(nullptr, nullptr, ErrorPath{});
Expand Down
3 changes: 2 additions & 1 deletion lib/checkcondition.h
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Expand Up @@ -84,7 +84,7 @@ class CPPCHECKLIB CheckCondition : public Check {
/**
* multiconditions #2
* - Opposite inner conditions => always false
* - (TODO) Same/Overlapping inner condition => always true
* - Same/Overlapping inner condition => always true
* - same condition after early exit => always false
**/
void multiCondition2();
Expand Down Expand Up @@ -130,6 +130,7 @@ class CPPCHECKLIB CheckCondition : public Check {
bool result);
void duplicateConditionError(const Token *tok1, const Token *tok2, ErrorPath errorPath);
void overlappingElseIfConditionError(const Token *tok, nonneg int line1);
void overlappingInnerConditionError(const Token *tok1, const Token *tok2, ErrorPath errorPath);
void oppositeElseIfConditionError(const Token *ifCond, const Token *elseIfCond, ErrorPath errorPath);

void oppositeInnerConditionError(const Token *tok1, const Token* tok2, ErrorPath errorPath);
Expand Down
18 changes: 18 additions & 0 deletions test/testcondition.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,8 @@ class TestCondition : public TestFixture {
TEST_CASE(identicalConditionAfterEarlyExit);
TEST_CASE(innerConditionModified);

TEST_CASE(overlappingInnerCondition);

TEST_CASE(clarifyCondition1); // if (a = b() < 0)
TEST_CASE(clarifyCondition2); // if (a & b == c)
TEST_CASE(clarifyCondition3); // if (! a & b)
Expand Down Expand Up @@ -3022,6 +3024,22 @@ class TestCondition : public TestFixture {
ASSERT_EQUALS("", errout_str());
}

void overlappingInnerCondition() {
check("void f(int x) {\n"
" if (x == 1) {\n"
" if (x & 7) {}\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:2:11] -> [test.cpp:3:15]: (warning) Overlapping inner 'if' condition is always true. [overlappingInnerCondition]\n", errout_str());

check("void f(int x) {\n"
" if (x & 7) {\n"
" if (x == 1) {}\n"
" }\n"
"}");
ASSERT_EQUALS("", errout_str());
}

// clarify conditions with = and comparison
void clarifyCondition1() {
check("void f() {\n"
Expand Down
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