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Fix #15067: False positive: unreadVariable with overloaded subscript operator. #8895

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Merged
ludviggunne merged 2 commits into from
Sep 25, 2026
+16 −0
Merged

Fix #15067: False positive: unreadVariable with overloaded subscript operator. #8895

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d8c60bc
test
ludviggunne Sep 24, 2026
31c1fc2
fix
ludviggunne Sep 24, 2026
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5 changes: 5 additions & 0 deletions lib/checkunusedvar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1288,6 +1288,11 @@ void CheckUnusedVarImpl::checkFunctionVariableUsage()
while (Token::Match(op1tok, ".|[|*"))
op1tok = op1tok->astOperand1();

// Bail out for overloaded indexing
if (op1tok && op1tok->valueType() && op1tok->valueType()->pointer == 0 &&
op1tok->valueType()->type == ValueType::Type::RECORD && Token::simpleMatch(op1tok->astParent(), "["))
continue;

// Assignment in macro => do not warn
if (isAssignment && tok->isExpandedMacro() && op1tok && op1tok->isExpandedMacro())
continue;
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11 changes: 11 additions & 0 deletions test/testunusedvar.cpp
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Expand Up @@ -225,6 +225,7 @@ class TestUnusedVar : public TestFixture {
TEST_CASE(localvarStruct13); // #10398
TEST_CASE(localvarStruct14);
TEST_CASE(localvarStructArray);
TEST_CASE(localvarOverloadedSubscript);
TEST_CASE(localvarUnion1);

TEST_CASE(localvarOp); // Usage with arithmetic operators
Expand Down Expand Up @@ -5666,6 +5667,16 @@ class TestUnusedVar : public TestFixture {
ASSERT_EQUALS("[test.cpp:3:12]: (style) Variable 'x[0].a' is assigned a value that is never used. [unreadVariable]\n", errout_str());
}

void localvarOverloadedSubscript() {
functionVariableUsage("struct A { B &operator [](size_t i); }\n"
"struct B { int x; };\n"
"void f(B *b) {\n"
" A a(b);\n"
" a[0].b = 0;\n"
"}\n");
ASSERT_EQUALS("", errout_str());
}

void localvarUnion1() {
// #9707
functionVariableUsage("static short read(FILE *fp) {\n"
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