Handle reverse conditions in isOppositeCond function

Signed-off-by: Francois Berder <fberder@outlook.fr>

Author: francois-berder

lib/astutils.cpp

@@ -1810,21 +1810,32 @@ bool isSameExpression(bool macro, const Token *tok1, const Token *tok2, const Se
     return commutativeEquals;
 }
 
-static bool isZeroBoundCond(const Token * const cond)
+static bool isZeroBoundCond(const Token * const cond, bool reverse)
 {
     if (cond == nullptr)
         return false;
     // Assume unsigned
-    // TODO: Handle reverse conditions
-    const bool isZero = cond->astOperand2()->getValue(0);
-    if (cond->str() == "==" || cond->str() == ">=")
-        return isZero;
-    if (cond->str() == "<=")
-        return true;
-    if (cond->str() == "<")
-        return !isZero;
-    if (cond->str() == ">")
-        return false;
+    const bool isZero = reverse ? cond->astOperand1()->getValue(0) : cond->astOperand2()->getValue(0);
+    if (reverse) {
+        if (cond->str() == "==" || cond->str() == "<=")
+            return isZero;
+        if (cond->str() == ">=")
+            return true;
+        if (cond->str() == ">")
+            return !isZero;
+        if (cond->str() == "<")
+            return false;
+    } else {
+        if (cond->str() == "==" || cond->str() == ">=")
+            return isZero;
+        if (cond->str() == "<=")
+            return true;
+        if (cond->str() == "<")
+            return !isZero;
+        if (cond->str() == ">")
+            return false;
+    }
+
     return false;
 }
 
@@ -1888,7 +1899,7 @@ bool isOppositeCond(bool isNot, const Token * const cond1, const Token * const c
             if (isSameExpression(true, cond1->astOperand2(), cond2->astOperand2(), settings, pure, followVar, errors))
                 return isDifferentKnownValues(cond1->astOperand1(), cond2->astOperand1());
         }
-        // TODO: Handle reverse conditions
+
         if (Library::isContainerYield(cond1, Library::Container::Yield::EMPTY, "empty") &&
             Library::isContainerYield(cond2->astOperand1(), Library::Container::Yield::SIZE, "size") &&
             isSameExpression(true,
@@ -1898,7 +1909,19 @@ bool isOppositeCond(bool isNot, const Token * const cond1, const Token * const c
                              pure,
                              followVar,
                              errors)) {
-            return !isZeroBoundCond(cond2);
+            return !isZeroBoundCond(cond2, false);
+        }
+
+        if (Library::isContainerYield(cond1, Library::Container::Yield::EMPTY, "empty") &&
+            Library::isContainerYield(cond2->astOperand2(), Library::Container::Yield::SIZE, "size") &&
+            isSameExpression(true,
+                             cond1->astOperand1()->astOperand1(),
+                             cond2->astOperand2()->astOperand1()->astOperand1(),
+                             settings,
+                             pure,
+                             followVar,
+                             errors)) {
+            return !isZeroBoundCond(cond2, true);
         }
 
         if (Library::isContainerYield(cond2, Library::Container::Yield::EMPTY, "empty") &&
@@ -1910,7 +1933,19 @@ bool isOppositeCond(bool isNot, const Token * const cond1, const Token * const c
                              pure,
                              followVar,
                              errors)) {
-            return !isZeroBoundCond(cond1);
+            return !isZeroBoundCond(cond1, false);
+        }
+
+        if (Library::isContainerYield(cond2, Library::Container::Yield::EMPTY, "empty") &&
+            Library::isContainerYield(cond1->astOperand2(), Library::Container::Yield::SIZE, "size") &&
+            isSameExpression(true,
+                             cond2->astOperand1()->astOperand1(),
+                             cond1->astOperand2()->astOperand1()->astOperand1(),
+                             settings,
+                             pure,
+                             followVar,
+                             errors)) {
+            return !isZeroBoundCond(cond1, true);
         }
     }
 

test/testcondition.cpp

@@ -2674,6 +2674,12 @@ class TestCondition : public TestFixture {
         check("void f1(const std::string &s) { if(s.size() >= 0) if(s.empty()) {}} "); // CheckOther says: Unsigned expression 's.size()' can't be negative so it is unnecessary to test it. [unsignedPositive]
         ASSERT_EQUALS("", errout_str());
 
+        check("void f1(const std::string &s) { if(42 < s.size()) if(s.empty()) {}}");
+        ASSERT_EQUALS("[test.cpp:1:39] -> [test.cpp:1:61]: (warning) Opposite inner 'if' condition leads to a dead code block. [oppositeInnerCondition]\n", errout_str());
+
+        check("void f1(const std::string &s) { if(s.empty()) if(42 < s.size()) {}}");
+        ASSERT_EQUALS("[test.cpp:1:43] -> [test.cpp:1:53]: (warning) Opposite inner 'if' condition leads to a dead code block. [oppositeInnerCondition]\n", errout_str());
+
         // TODO: These are identical condition since size cannot be negative
         check("void f1(const std::string &s) { if(s.size() <= 0) if(s.empty()) {}}");
         ASSERT_EQUALS("", errout_str());