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constStatementError: don't warn for casts with possible side effects,… (#3885) 

* constStatementError: don't warn for casts with possible side effects, handle bool constants

* Recursive call, add tests

* Restore test

* Don't warn for C++ casts to void

* Don't warn for cast to void*
This commit is contained in:
chrchr-github 2022-03-11 21:45:51 +01:00 committed by GitHub
parent ffd9f9a93f
commit 705931266c
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2 changed files with 47 additions and 7 deletions
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24
lib/checkother.cpp
View File

@ -1739,7 +1739,7 @@ static bool isVarDeclOp(const Token* tok)
return isType(typetok, Token::Match(vartok, "%var%"));
}
static bool isConstStatement(const Token *tok)
static bool isConstStatement(const Token *tok, bool cpp)
{
if (!tok)
return false;
@ -1759,11 +1759,13 @@ static bool isConstStatement(const Token *tok)
if (Token::simpleMatch(tok->previous(), "sizeof ("))
return true;
if (isCPPCast(tok))
return isConstStatement(tok->astOperand2());
return isWithoutSideEffects(cpp, tok) && isConstStatement(tok->astOperand2(), cpp);
else if (tok->isCast())
return isWithoutSideEffects(cpp, tok->astOperand1()) && isConstStatement(tok->astOperand1(), cpp);
if (Token::Match(tok, "( %type%"))
return isConstStatement(tok->astOperand1());
return isConstStatement(tok->astOperand1(), cpp);
if (Token::simpleMatch(tok, ","))
return isConstStatement(tok->astOperand2());
return isConstStatement(tok->astOperand2(), cpp);
return false;
}
@ -1771,6 +1773,8 @@ static bool isVoidStmt(const Token *tok)
{
if (Token::simpleMatch(tok, "( void"))
return true;
if (isCPPCast(tok) && tok->astOperand1() && Token::Match(tok->astOperand1()->next(), "< void *| >"))
return true;
const Token *tok2 = tok;
while (tok2->astOperand1())
tok2 = tok2->astOperand1();
@ -1838,7 +1842,7 @@ void CheckOther::checkIncompleteStatement()
// Skip statement expressions
if (Token::simpleMatch(rtok, "; } )"))
continue;
if (!isConstStatement(tok))
if (!isConstStatement(tok, mTokenizer->isCPP()))
continue;
if (isVoidStmt(tok))
continue;
@ -1864,8 +1868,14 @@ void CheckOther::constStatementError(const Token *tok, const std::string &type,
msg = "Found suspicious operator '" + tok->str() + "'";
else if (Token::Match(tok, "%var%"))
msg = "Unused variable value '" + tok->str() + "'";
else if (Token::Match(valueTok, "%str%|%num%"))
msg = "Redundant code: Found a statement that begins with " + std::string(valueTok->isNumber() ? "numeric" : "string") + " constant.";
else if (Token::Match(valueTok, "%str%|%num%|%bool%")) {
std::string typeStr("string");
if (valueTok->isNumber())
typeStr = "numeric";
else if (valueTok->isBoolean())
typeStr = "bool";
msg = "Redundant code: Found a statement that begins with " + typeStr + " constant.";
}
else if (!tok)
msg = "Redundant code: Found a statement that begins with " + type + " constant.";
else if (tok->isCast() && tok->tokType() == Token::Type::eExtendedOp) {

30
test/testincompletestatement.cpp
View File

@ -386,6 +386,36 @@ private:
check("void f(int x) { static_cast<unsigned>(x); }");
ASSERT_EQUALS("[test.cpp:1]: (warning) Found unused cast of expression 'x'.\n", errout.str());
check("void f(int x, int* p) {\n"
" static_cast<void>(x);\n"
" (void)x;\n"
" static_cast<void*>(p);\n"
" (void*)p;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f() { false; }"); // #10856
ASSERT_EQUALS("[test.cpp:1]: (warning) Redundant code: Found a statement that begins with bool constant.\n", errout.str());
check("void f(int i) {\n"
" (float)(char)i;\n"
" static_cast<float>((char)i);\n"
" (char)static_cast<float>(i);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (warning) Found unused cast of expression 'i'.\n"
"[test.cpp:3]: (warning) Found unused cast of expression 'i'.\n"
"[test.cpp:4]: (warning) Found unused cast of expression 'i'.\n",
errout.str());
check("struct S; struct T; struct U;\n"
"void f() {\n"
" T t;\n"
" (S)(U)t;\n"
" (S)static_cast<U>(t);\n"
" static_cast<S>((U)t);\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
void vardecl() {