C++: Improvements to "Declaration hides parameter"

cpp/ql/src/Best Practices/Hiding/DeclarationHidesParameter.ql

@@ -8,29 +8,38 @@
  * @tags maintainability
  *       readability
  */
-import cpp
 
+import cpp
 
-/* Names of parameters in the implementation of a function.
-   Notice that we need to exclude parameter names used in prototype
-   declarations and only include the ones from the actual definition.
-   We also exclude names from functions that have multiple definitions.
-   This should not happen in a single application but since we
-   have a system wide view it is likely to happen for instance for
-   the main function. */
+/**
+ * Gets the parameter of `f` with name `name`, which has to come from the
+ * _definition_ of `f` and not a prototype declaration.
+ * We also exclude names from functions that have multiple definitions.
+ * This should not happen in a single application but since we
+ * have a system wide view it is likely to happen for instance for
+ * the main function.
+ */
 ParameterDeclarationEntry functionParameterNames(Function f, string name) {
   exists(FunctionDeclarationEntry fe |
-    result.getFunctionDeclarationEntry() = fe
-    and fe.getFunction() = f
-    and fe.getLocation() = f.getDefinitionLocation()
-    and strictcount(f.getDefinitionLocation()) = 1
-    and result.getName() = name
+    result.getFunctionDeclarationEntry() = fe and
+    fe.getFunction() = f and
+    fe.getLocation() = f.getDefinitionLocation() and
+    result.getFile() = fe.getFile() and // Work around CPP-331
+    strictcount(f.getDefinitionLocation()) = 1 and
+    result.getName() = name
   )
 }
 
-from Function f, LocalVariable lv, ParameterDeclarationEntry pde
-where f = lv.getFunction() and
-      pde = functionParameterNames(f, lv.getName()) and
-      not lv.isInMacroExpansion()
-select lv, "Local variable '"+ lv.getName() +"' hides a $@.",
-       pde, "parameter of the same name"
+/** Gets a local variable in `f` with name `name`. */
+pragma[nomagic]
+LocalVariable localVariableNames(Function f, string name) {
+  name = result.getName() and
+  f = result.getFunction()
+}
+
+from Function f, LocalVariable lv, ParameterDeclarationEntry pde, string name
+where
+  lv = localVariableNames(f, name) and
+  pde = functionParameterNames(f, name) and
+  not lv.isInMacroExpansion()
+select lv, "Local variable '" + lv.getName() + "' hides a $@.", pde, "parameter of the same name"