Partial fix for #12529 FN unreadVariable/unusedVariable with library type (#6170)

Author: chrchr-github

lib/checkunusedvar.cpp

@@ -1201,8 +1201,9 @@ void CheckUnusedVar::checkFunctionVariableUsage()
             if (!isAssignment && !isInitialization && !isIncrementOrDecrement)
                 continue;
 
+            bool isTrivialInit = false;
             if (isInitialization && Token::Match(tok, "%var% { }")) // don't warn for trivial initialization
-                continue;
+                isTrivialInit = true;
 
             if (isIncrementOrDecrement && tok->astParent() && precedes(tok, tok->astOperand1()))
                 continue;
@@ -1308,6 +1309,8 @@ void CheckUnusedVar::checkFunctionVariableUsage()
                         reportLibraryCfgError(tok, bailoutTypeName);
                     continue;
                 }
+                if (isTrivialInit && findExpressionChanged(expr, start, scopeEnd, mSettings))
+                    continue;
 
                 // warn
                 if (!expr->variable() || !expr->variable()->isMaybeUnused())

test/cfg/wxwidgets.cpp

@@ -87,7 +87,7 @@ void unreadVariable_wxTimeSpan(const long x, const wxLongLong y)
 {
     // cppcheck-suppress unusedVariable
     wxTimeSpan a;
-    // TODO cppcheck-suppress unreadVariable
+    // cppcheck-suppress unreadVariable
     wxTimeSpan b{};
     // cppcheck-suppress unreadVariable
     wxTimeSpan c{x};
@@ -109,7 +109,7 @@ void unreadVariable_wxPosition(const int x)
 {
     // cppcheck-suppress unusedVariable
     wxPosition a;
-    // TODO cppcheck-suppress unreadVariable
+    // cppcheck-suppress unreadVariable
     wxPosition b{};
     // cppcheck-suppress unreadVariable
     wxPosition c{x,x};
@@ -129,7 +129,7 @@ void unreadVariable_wxRegion(const wxCoord x, const wxPoint &pt, const wxRect &r
 {
     // cppcheck-suppress unusedVariable
     wxRegion a;
-    // TODO cppcheck-suppress unreadVariable
+    // cppcheck-suppress unreadVariable
     wxRegion b{};
     // cppcheck-suppress unreadVariable
     wxRegion c{x,x,x,x};
@@ -165,7 +165,7 @@ void unreadVariable_wxSize(const wxSize &s)
 {
     // cppcheck-suppress unusedVariable
     wxSize a;
-    // TODO cppcheck-suppress unreadVariable
+    // cppcheck-suppress unreadVariable
     wxSize b{};
     // cppcheck-suppress unreadVariable
     wxSize c{4, 2};
@@ -179,7 +179,7 @@ void unreadVariable_wxPoint(const wxRealPoint &rp, const int x, const int y)
 {
     // cppcheck-suppress unusedVariable
     wxPoint a;
-    // TODO cppcheck-suppress unreadVariable
+    // cppcheck-suppress unreadVariable
     wxPoint b{};
     // cppcheck-suppress unreadVariable
     wxPoint c{4, 2};
@@ -197,7 +197,7 @@ void unreadVariable_wxRealPoint(const wxPoint &pt, const double x, const double
 {
     // cppcheck-suppress unusedVariable
     wxRealPoint a;
-    // TODO cppcheck-suppress unreadVariable
+    // cppcheck-suppress unreadVariable
     wxRealPoint b{};
     // cppcheck-suppress unreadVariable
     wxRealPoint c{4.0, 2.0};
@@ -215,7 +215,7 @@ void unreadVariable_wxRect(const int x, const wxPoint &pt, const wxSize &sz)
 {
     // cppcheck-suppress unusedVariable
     wxRect a;
-    // TODO cppcheck-suppress unreadVariable
+    // cppcheck-suppress unreadVariable
     wxRect b{};
     // cppcheck-suppress unreadVariable
     wxRect c{x,x,x,x};

test/testunusedvar.cpp

@@ -3778,7 +3778,7 @@ class TestUnusedVar : public TestFixture {
         functionVariableUsage("void f() {\n"
                               "    S* s{};\n"
                               "}\n");
-        TODO_ASSERT_EQUALS("[test.cpp:2]: (style) Variable 's' is assigned a value that is never used.\n", "", errout_str());
+        ASSERT_EQUALS("[test.cpp:2]: (style) Variable 's' is assigned a value that is never used.\n", errout_str());
 
         functionVariableUsage("int f() {\n"
                               "    int i = 0, j = 1;\n"
@@ -5137,7 +5137,7 @@ class TestUnusedVar : public TestFixture {
                               "        b = false;\n"
                               "    if (*p) {}\n"
                               "}\n");
-        ASSERT_EQUALS("", errout_str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) Variable 'j' is assigned a value that is never used.\n", errout_str());
     }
 
     void localvaralias22() { // #11139