Fix #11368 FP "Same value in both branches of ternary operator" on plus and minus zero (cppcheck-opensource#4569)

chrchr-github · web-flow · commit cf8051b7e2e9 · 2022-10-31T15:18:25.000+01:00
Fix #11368 FP "Same value in both branches of ternary operator" on plus and minus zero
diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
@@ -468,9 +468,6 @@ double MathLib::toDoubleNumber(const std::string &str)
     }
     if (isIntHex(str))
         return static_cast<double>(toLongNumber(str));
-    // nullcheck
-    if (isNullValue(str))
-        return 0.0;
 #ifdef _LIBCPP_VERSION
     if (isFloat(str)) // Workaround libc++ bug at http://llvm.org/bugs/show_bug.cgi?id=17782
         // TODO : handle locale
@@ -1053,7 +1050,7 @@ std::string MathLib::divide(const std::string &first, const std::string &second)
     } else if (isNullValue(second)) {
         if (isNullValue(first))
             return "nan.0";
-        return isPositive(first) ? "inf.0" : "-inf.0";
+        return isPositive(first) == isPositive(second) ? "inf.0" : "-inf.0";
     }
     return toString(toDoubleNumber(first) / toDoubleNumber(second));
 #endif
diff --git a/lib/valueflow.h b/lib/valueflow.h
@@ -26,6 +26,7 @@
 
 #include <cassert>
 #include <cstdlib>
+#include <cmath>
 #include <functional>
 #include <list>
 #include <string>
@@ -130,8 +131,7 @@ namespace ValueFlow {
                     return false;
                 break;
             case ValueType::FLOAT:
-                // TODO: Write some better comparison
-                if (floatValue > rhs.floatValue || floatValue < rhs.floatValue)
+                if (floatValue > rhs.floatValue || floatValue < rhs.floatValue || std::signbit(floatValue) != std::signbit(rhs.floatValue))
                     return false;
                 break;
             case ValueType::MOVED:
diff --git a/test/testmathlib.cpp b/test/testmathlib.cpp
@@ -977,7 +977,7 @@ class TestMathLib : public TestFixture {
         ASSERT_EQUALS("inf.0", MathLib::divide("3.0", "0.f")); // inf (#5875)
         ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "0.0")); // -inf (#5142)
         ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "0.0f")); // -inf (#5142)
-        ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "-0.0f")); // inf (#5142)
+        ASSERT_EQUALS("inf.0", MathLib::divide("-3.0", "-0.0f")); // inf (#5142)
     }
 
     void isdec() const {
diff --git a/test/testother.cpp b/test/testother.cpp
@@ -6463,6 +6463,11 @@ class TestOther : public TestFixture {
               "    return f;\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("float f(float x) {\n" // # 11368
+              "    return (x >= 0.0) ? 0.0 : -0.0;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void duplicateExpressionTemplate() {

Original file line number	Diff line number	Diff line change
`@@ -977,7 +977,7 @@ class TestMathLib : public TestFixture {`
`977`	`977`	`ASSERT_EQUALS("inf.0", MathLib::divide("3.0", "0.f")); // inf (#5875)`
`978`	`978`	`ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "0.0")); // -inf (#5142)`
`979`	`979`	`ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "0.0f")); // -inf (#5142)`
`980`		`- ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "-0.0f")); // inf (#5142)`
	`980`	`+ ASSERT_EQUALS("inf.0", MathLib::divide("-3.0", "-0.0f")); // inf (#5142)`
`981`	`981`	`}`
`982`	`982`
`983`	`983`	`void isdec() const {`