[clang] [clang-tools-extra] [clang-tidy] Avoid matching nodes in system headers (PR #151035)

[Carlos Galvez via cfe-commits]

================
@@ -1336,6 +1336,44 @@ class MatchASTVisitor : public RecursiveASTVisitor<MatchASTVisitor>,
     return false;
   }
 
+  template <typename T> static SourceLocation getNodeLocation(const T &Node) {
+    return Node.getBeginLoc();
+  }
+
+  static SourceLocation getNodeLocation(const QualType &Node) { return {}; }
+
+  static SourceLocation getNodeLocation(const NestedNameSpecifier &Node) {
+    return {};
+  }
+
+  static SourceLocation getNodeLocation(const CXXCtorInitializer &Node) {
+    return Node.getSourceLocation();
+  }
+
+  static SourceLocation getNodeLocation(const TemplateArgumentLoc &Node) {
+    return Node.getLocation();
+  }
+
+  static SourceLocation getNodeLocation(const Attr &Node) {
+    return Node.getLocation();
+  }
+
+  bool isInSystemHeader(const SourceLocation &Loc) {
+    const SourceManager &SM = getASTContext().getSourceManager();
+    return SM.isInSystemHeader(Loc);
+  }
+
+  template <typename T> bool shouldSkipNode(const T &Node) {
+    if constexpr (std::is_pointer_v<T>)
+      return (Node == nullptr) || shouldSkipNode(*Node);
+    else {
+      if (Options.IgnoreSystemHeaders &&
+          isInSystemHeader(getNodeLocation(Node)))
+        return true;
+      return false;
----------------
carlosgalvezp wrote:

This suggestion will likely need to be undone soon, by the above-mentioned PR regarding modules, like:

```cpp
if (SystemHeaders)
{
  return true;
}
else if (Modules)
{
  return true;
}
return false;
```

https://github.com/llvm/llvm-project/pull/151035