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Fix #12618 FN variableScope with member or array access #6301

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merged 5 commits into from
Apr 18, 2024
Merged

Fix #12618 FN variableScope with member or array access #6301

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320381f
Update checkother.cpp
chrchr-github Apr 17, 2024
26722c2
Update testother.cpp
chrchr-github Apr 17, 2024
a7b0eb8
Update valueflow.cpp
chrchr-github Apr 17, 2024
785b11d
Update checkother.cpp
chrchr-github Apr 17, 2024
a2af205
Update checkother.cpp
chrchr-github Apr 17, 2024
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14 changes: 10 additions & 4 deletions lib/checkother.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -911,14 +911,20 @@ static bool isSimpleExpr(const Token* tok, const Variable* var, const Settings*
return true;
bool needsCheck = tok->varId() > 0;
if (!needsCheck) {
if (tok->isArithmeticalOp())
return isSimpleExpr(tok->astOperand1(), var, settings) && (!tok->astOperand2() || isSimpleExpr(tok->astOperand2(), var, settings));
const Token* ftok = tok->previous();
if (Token::Match(ftok, "%name% (") &&
((ftok->function() && ftok->function()->isConst()) || settings->library.isFunctionConst(ftok->str(), /*pure*/ true)))
needsCheck = true;
if (tok->isArithmeticalOp() &&
(!tok->astOperand1() || isSimpleExpr(tok->astOperand1(), var, settings)) &&
(!tok->astOperand2() || isSimpleExpr(tok->astOperand2(), var, settings)))
return true;
else if (tok->str() == "[") {
needsCheck = tok->astOperand1() && tok->astOperand1()->varId() > 0;
tok = tok->astOperand1();
}
else if (isLeafDot(tok->astOperand2())) {
needsCheck = tok->astOperand2()->varId() > 0;
tok = tok->astOperand2();
}
}
return (needsCheck && !findExpressionChanged(tok, tok->astParent(), var->scope()->bodyEnd, settings));
}
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3 changes: 1 addition & 2 deletions lib/valueflow.cpp
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Expand Up @@ -8438,9 +8438,8 @@ bool ValueFlow::isContainerSizeChanged(const Token* tok, int indirect, const Set
return true;
if (astIsLHS(tok) && Token::Match(tok->astParent(), "%assign%|<<"))
return true;
const Library::Container* container = tok->valueType()->container;
if (astIsLHS(tok) && Token::simpleMatch(tok->astParent(), "["))
return container->stdAssociativeLike;
return tok->valueType()->container->stdAssociativeLike;
const Library::Container::Action action = astContainerAction(tok);
switch (action) {
case Library::Container::Action::RESIZE:
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15 changes: 14 additions & 1 deletion test/testother.cpp
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Expand Up @@ -1712,7 +1712,7 @@ class TestOther : public TestFixture {
}

void varScope40() {
checkP("#define NUM (-999.9)\n"
checkP("#define NUM (-999.9)\n" // #8862
"double f(int i) {\n"
" double a = NUM;\n"
" double b = -NUM;\n"
Expand All @@ -1732,6 +1732,19 @@ class TestOther : public TestFixture {
"[test.cpp:4]: (style) The scope of the variable 'b' can be reduced.\n"
"[test.cpp:5]: (style) The scope of the variable 'c' can be reduced.\n",
errout_str());

check("struct S { int a; };\n" // #12618
"int f(const S* s, int i) {\n"
" int x = s->a;\n"
" const int b[] = { 1, 2, 3 };\n"
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Even the scope of 'b' could be reduced.

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yeah.. but that requires that scope of y can be reduced. I don't know if we will warn about b if y is moved.

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We don't warn for arrays because of

if (Token::Match(tok, "= %varid%", var->declarationId()) && (var->isArray() || var->isPointer() || (var->valueType() && var->valueType()->container))) // Create a copy of array/pointer. Bailout, because the memory it points to might be necessary in outer scope
            return false;

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ok it's a bailout we should fix.. good that the comment says "bailout" explicitly so we can search for it..

" int y = b[1];\n"
" if (i)\n"
" return x + y;\n"
" return 0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) The scope of the variable 'x' can be reduced.\n"
"[test.cpp:5]: (style) The scope of the variable 'y' can be reduced.\n",
errout_str());
}

#define checkOldStylePointerCast(code) checkOldStylePointerCast_(code, __FILE__, __LINE__)
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