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Fixed #4109 (if (c == 1) c == 0; Isn't picked up)

This commit is contained in:
Zachary Blair 2013-01-17 23:03:04 -08:00
parent 77e9f65e6b
commit a1cbed3df8
3 changed files with 161 additions and 0 deletions
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58
lib/checkother.cpp
View File

@ -1105,6 +1105,64 @@ void CheckOther::suspiciousCaseInSwitchError(const Token* tok, const std::string
"Using an operator like '" + operatorString + "' in a case label is suspicious. Did you intend to use a bitwise operator, multiple case labels or if/else instead?", true);
}
//---------------------------------------------------------------------------
// if (x == 1)
// x == 0; // <- suspicious equality comparison.
//---------------------------------------------------------------------------
void CheckOther::checkSuspiciousEqualityComparison()
{
if (!_settings->isEnabled("style"))
return;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
if (Token::simpleMatch(tok, "for (")) {
// Search for any suspicious equality comparison in the initialization
// or increment-decrement parts of the for() loop.
// For example:
// for (i == 2; i < 10; i++)
// or
// for (i = 0; i < 10; i == a)
const Token* tok2 = Token::findmatch(tok->next(), "[;(] %var% == %any% [;)]", tok->linkAt(1));
if (tok2 && (tok2->str() == "(" || tok2->strAt(4) == ")")) {
suspiciousEqualityComparisonError(tok2->tokAt(2));
}
// Equality comparisons with 0 are simplified to negation. For instance,
// (x == 0) is simplified to (!x), so also check for suspicious negation
// in the initialization or increment-decrement parts of the for() loop.
// For example:
// for (!i; i < 10; i++)
const Token* tok3 = Token::findmatch(tok->next(), "[;(] ! %var% [;)]", tok->linkAt(1));
if (tok3 && (tok3->str() == "(" || tok3->strAt(3) == ")")) {
suspiciousEqualityComparisonError(tok3->tokAt(2));
}
// Skip over for() loop conditions because "for (;running==1;)"
// is a bit strange, but not necessarily incorrect.
tok = tok->linkAt(1);
}
if (Token::Match(tok, "[;{}] *| %var% == %any% ;")) {
// Exclude compound statements surrounded by parentheses, such as
// printf("%i\n", ({x==0;}));
// because they may appear as an expression in GNU C/C++.
// See http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html
const Token* afterStatement = tok->strAt(1) == "*" ? tok->tokAt(6) : tok->tokAt(5);
if (!Token::simpleMatch(afterStatement, "} )"))
suspiciousEqualityComparisonError(tok->next());
}
}
}
void CheckOther::suspiciousEqualityComparisonError(const Token* tok)
{
reportError(tok, Severity::warning, "suspiciousEqualityComparison",
"Found suspicious equality comparison. Did you intend to assign a value instead?", true);
}
//---------------------------------------------------------------------------
// int x = 1;

7
lib/checkother.h
View File

@ -116,6 +116,7 @@ public:
checkOther.checkDoubleFree();
checkOther.checkRedundantCopy();
checkOther.checkNegativeBitwiseShift();
checkOther.checkSuspiciousEqualityComparison();
}
/** To check the dead code in a program, which is unaccessible due to the counter-conditions check in nested-if statements **/
@ -191,6 +192,9 @@ public:
/** @brief %Check for code like 'case A||B:'*/
void checkSuspiciousCaseInSwitch();
/** @brief %Check for code like 'case A||B:'*/
void checkSuspiciousEqualityComparison();
/** @brief %Check for switch case fall through without comment */
void checkSwitchCaseFallThrough();
@ -320,6 +324,7 @@ private:
void redundantBitwiseOperationInSwitchError(const Token *tok, const std::string &varname);
void switchCaseFallThrough(const Token *tok);
void suspiciousCaseInSwitchError(const Token* tok, const std::string& operatorString);
void suspiciousEqualityComparisonError(const Token* tok);
void selfAssignmentError(const Token *tok, const std::string &varname);
void assignmentInAssertError(const Token *tok, const std::string &varname);
void incorrectLogicOperatorError(const Token *tok, const std::string &condition, bool always);
@ -403,6 +408,7 @@ private:
c.redundantCopyInSwitchError(0, 0, "var");
c.switchCaseFallThrough(0);
c.suspiciousCaseInSwitchError(0, "||");
c.suspiciousEqualityComparisonError(0);
c.selfAssignmentError(0, "varname");
c.assignmentInAssertError(0, "varname");
c.incorrectLogicOperatorError(0, "foo > 3 && foo < 4", true);
@ -482,6 +488,7 @@ private:
"* look for suspicious calculations with sizeof()\n"
"* assignment of a variable to itself\n"
"* Suspicious case labels in switch()\n"
"* Suspicious equality comparisons\n"
"* mutual exclusion over || always evaluating to true\n"
"* Clarify calculation with parentheses\n"
"* using increment on boolean\n"

96
test/testother.cpp
View File

@ -88,6 +88,7 @@ private:
TEST_CASE(unreachableCode);
TEST_CASE(suspiciousCase);
TEST_CASE(suspiciousEqualityComparison);
TEST_CASE(selfAssignment);
TEST_CASE(trac1132);
@ -2769,6 +2770,101 @@ private:
ASSERT_EQUALS("", errout.str());
}
void suspiciousEqualityComparison() {
check("void foo(int c) {\n"
" if (c == 1) {\n"
" c == 0;\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:3]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int c) {\n"
" if (c == 1) c == 0;\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int* c) {\n"
" if (*c == 1) *c == 0;\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int c) {\n"
" if (c == 1) {\n"
" c = 0;\n"
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int c) {\n"
" c == 1;\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int c) {\n"
" for (int i = 0; i == 10; i ++) {\n"
" a ++;\n"
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int c) {\n"
" for (i == 0; i < 10; i ++) {\n"
" c ++;\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int c) {\n"
" for (i == 1; i < 10; i ++) {\n"
" c ++;\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int c) {\n"
" for (i == 2; i < 10; i ++) {\n"
" c ++;\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int c) {\n"
" for (int i = 0; i < 10; i == c) {\n"
" c ++;\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
check("void foo(int c) {\n"
" for (; running == 1;) {\n"
" c ++;\n"
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int c) {\n"
" for (; running == 1;) {\n"
" c ++;\n"
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int c) {\n"
" printf(\"%i\n\", ({x==0;}));\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int x) {\n"
" printf(\"%i\n\", ({int x = do_something(); x == 0;}));\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int x) {\n"
" printf(\"%i\n\", ({x == 0; x > 0 ? 10 : 20}));\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning, inconclusive) Found suspicious equality comparison. Did you intend to assign a value instead?\n", errout.str());
}
void selfAssignment() {
check("void foo()\n"