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Fix #13148 FN: constStatement (static_cast<void>(integer|nullptr|NULL)) #8694

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Fix #13148 FN: constStatement (static_cast<void>(integer|nullptr|NULL)) #8694

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84bf3bf
Update checkother.cpp
chrchr-github Jul 3, 2026
256f3c3
Update testincompletestatement.cpp
chrchr-github Jul 3, 2026
b4c8be1
Fix
web-flow Jul 3, 2026
6fb5cb0
Update cfg.c
chrchr-github Jul 3, 2026
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14 changes: 4 additions & 10 deletions lib/checkother.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2323,18 +2323,12 @@ static bool isConstStatement(const Token *tok, const Library& library, bool plat

static bool isVoidStmt(const Token *tok)
{
if (Token::simpleMatch(tok, "( void"))
if (Token::simpleMatch(tok, "( void") && !(tok->astOperand1() && (tok->astOperand1()->isLiteral() || isNullOperand(tok->astOperand1()))))
return true;
if (isCPPCast(tok) && tok->astOperand1() && Token::Match(tok->astOperand1()->next(), "< void *| >"))
if (isCPPCast(tok) && tok->astOperand1() && Token::Match(tok->astOperand1()->next(), "< void *| >") &&
!(tok->astOperand2() && (tok->astOperand2()->isLiteral() || isNullOperand(tok->astOperand2()))))
return true;
const Token *tok2 = tok;
while (tok2->astOperand1())
tok2 = tok2->astOperand1();
if (Token::simpleMatch(tok2->previous(), ")") && Token::simpleMatch(tok2->linkAt(-1), "( void"))
return true;
if (Token::simpleMatch(tok2, "( void"))
return true;
return Token::Match(tok2->previous(), "delete|throw|return");
return false;
}

static bool isConstTop(const Token *tok)
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4 changes: 2 additions & 2 deletions test/cli/proj-inline-suppress/cfg.c
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Expand Up @@ -2,9 +2,9 @@ void f()
{
#if DEF_1
// cppcheck-suppress id
(void)0;
;
#endif

// cppcheck-suppress id
(void)0;
;
}
18 changes: 17 additions & 1 deletion test/testincompletestatement.cpp
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Expand Up @@ -180,9 +180,25 @@ class TestIncompleteStatement : public TestFixture {
}

void void0() { // #6327
check("void f() { (void*)0; }");
check("#define assert(x) ((void)0)\n"
"void f(int* p) {\n"
" assert(p);\n"
"}\n");
ASSERT_EQUALS("", errout_str());

check("void f() { (void*)0; }");
ASSERT_EQUALS("[test.cpp:1:12]: (warning) Redundant code: Found a statement that begins with numeric constant. [constStatement]\n", errout_str());

@danmar danmar Jul 11, 2026

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hmm.. the warning message is not technically correct. I would say that the cast comes before the numeric constant.
maybe we should try to reformulate this somehow.


check("void f() {\n" // #13148
" static_cast<void>(1);\n"
" static_cast<void>(nullptr);\n"
" (void)NULL;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2:22]: (warning) Redundant code: Found a statement that begins with numeric constant. [constStatement]\n"
"[test.cpp:3:22]: (warning) Redundant code: Found a statement that begins with NULL constant. [constStatement]\n"

@danmar danmar Jul 11, 2026

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Ideally we would not say that nullptr ist a NULL constant. can we write nullptr instead or null?

"[test.cpp:4:5]: (warning) Redundant code: Found a statement that begins with NULL constant. [constStatement]\n",

@danmar danmar Jul 11, 2026

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In this test case it just looks like a redundant statement , I wonder if the severity should be "style" instead. Are there bugs discovered by this checker or just code cleanup?

We could change the severity in a separate PR.

errout_str());

check("#define X 0\n"
"void f() { X; }");
ASSERT_EQUALS("", errout_str());
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7 changes: 5 additions & 2 deletions test/testother.cpp
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Expand Up @@ -3914,7 +3914,9 @@ class TestOther : public TestFixture {
" (void)(true);\n"
" if (r) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:1:13]: (style) Parameter 'r' can be declared as reference to const [constParameterReference]\n", errout_str());
ASSERT_EQUALS("[test.cpp:2:5]: (warning) Redundant code: Found a statement that begins with bool constant. [constStatement]\n"
"[test.cpp:1:13]: (style) Parameter 'r' can be declared as reference to const [constParameterReference]\n",
errout_str());

check("struct S { void f(int&); };\n" // #12216
"void g(S& s, int& r, void (S::* p2m)(int&)) {\n"
Expand Down Expand Up @@ -7012,7 +7014,8 @@ class TestOther : public TestFixture {
" std::pair<int, int>(1, 2);\n"
" (void)0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2:10]: (style) Instance of 'std::string' object is destroyed immediately. [unusedScopedObject]\n"
ASSERT_EQUALS("[test.cpp:5:5]: (warning) Redundant code: Found a statement that begins with numeric constant. [constStatement]\n"
"[test.cpp:2:10]: (style) Instance of 'std::string' object is destroyed immediately. [unusedScopedObject]\n"
"[test.cpp:3:10]: (style) Instance of 'std::string' object is destroyed immediately. [unusedScopedObject]\n"
"[test.cpp:4:10]: (style) Instance of 'std::pair' object is destroyed immediately. [unusedScopedObject]\n",
errout_str());
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