Fix #14783 / #14784 FN unusedVariable with templated type (default constructor, regression) (#8574)

Co-authored-by: chrchr-github <noreply@github.com>

Author: chrchr-github

lib/checkunusedvar.cpp

@@ -1155,10 +1155,6 @@ void CheckUnusedVarImpl::checkFunctionVariableUsage_iterateScopes(const Scope* c
                         variables.read(tok2->varId(), tok);
                 }
             }
-        } else if (tok->variable() && tok->variable()->isClass() && tok->variable()->type() &&
-                   (tok->variable()->type()->needInitialization == Type::NeedInitialization::False) &&
-                   tok->strAt(1) == ";") {
-            variables.write(tok->varId(), tok);
         }
     }
 }

test/testunusedvar.cpp

@@ -7083,6 +7083,24 @@ class TestUnusedVar : public TestFixture {
                               "    S<0> s;\n"
                               "}\n");
         ASSERT_EQUALS("[test.cpp:6:10]: (style) Unused variable: s [unusedVariable]\n", errout_str());
+
+        functionVariableUsage("template <typename T>\n" // #14783
+                              "struct A {\n"
+                              "    A() = default;\n"
+                              "};\n"
+                              "void f() {\n"
+                              "    A<int> a;\n"
+                              "}\n");
+        ASSERT_EQUALS("[test.cpp:6:12]: (style) Unused variable: a [unusedVariable]\n", errout_str());
+
+        functionVariableUsage("template <typename T>\n" // #14784
+                              "struct A {\n"
+                              "    A() {}\n"
+                              "};\n"
+                              "void f() {\n"
+                              "    A<int> a;\n"
+                              "}\n");
+        ASSERT_EQUALS("[test.cpp:6:12]: (style) Unused variable: a [unusedVariable]\n", errout_str());
     }
 
     void localvarFuncPtr() {
@@ -7171,6 +7189,7 @@ class TestUnusedVar : public TestFixture {
                               "void f() {\n"
                               "    Y y;\n"
                               "}"); // #4695
+        ASSERT_EQUALS("[test.cpp:6:7]: (style) Unused variable: y [unusedVariable]\n", errout_str());
     }
 
     void crash3() {