1 files changed, 60 insertions, 0 deletions
diff --git a/build/clang-plugin/MustOverrideChecker.cpp b/build/clang-plugin/MustOverrideChecker.cpp
new file mode 100644
index 0000000000..b19ae94aac
--- /dev/null
+++ b/build/clang-plugin/MustOverrideChecker.cpp
@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MustOverrideChecker.h"
+#include "CustomMatchers.h"
+
+void MustOverrideChecker::registerMatchers(MatchFinder *AstMatcher) {
+  AstMatcher->addMatcher(cxxRecordDecl(isDefinition()).bind("class"), this);
+}
+
+void MustOverrideChecker::registerPPCallbacks(CompilerInstance &CI) {
+  this->CI = &CI;
+}
+
+void MustOverrideChecker::check(const MatchFinder::MatchResult &Result) {
+  auto D = Result.Nodes.getNodeAs<CXXRecordDecl>("class");
+
+  // Look through all of our immediate bases to find methods that need to be
+  // overridden
+  typedef std::vector<CXXMethodDecl *> OverridesVector;
+  OverridesVector MustOverrides;
+  for (const auto &Base : D->bases()) {
+    // The base is either a class (CXXRecordDecl) or it's a templated class...
+    CXXRecordDecl *Parent = Base.getType()
+                                .getDesugaredType(D->getASTContext())
+                                ->getAsCXXRecordDecl();
+    // The parent might not be resolved to a type yet. In this case, we can't
+    // do any checking here. For complete correctness, we should visit
+    // template instantiations, but this case is likely to be rare, so we will
+    // ignore it until it becomes important.
+    if (!Parent) {
+      continue;
+    }
+    Parent = Parent->getDefinition();
+    for (const auto &M : Parent->methods()) {
+      if (hasCustomAttribute<moz_must_override>(M))
+        MustOverrides.push_back(M);
+    }
+  }
+
+  for (auto &O : MustOverrides) {
+    bool Overridden = false;
+    for (const auto &M : D->methods()) {
+      // The way that Clang checks if a method M overrides its parent method
+      // is if the method has the same name but would not overload.
+      if (getNameChecked(M) == getNameChecked(O) &&
+          !CI->getSema().IsOverload(M, O, false)) {
+        Overridden = true;
+        break;
+      }
+    }
+    if (!Overridden) {
+      diag(D->getLocation(), "%0 must override %1", DiagnosticIDs::Error)
+          << D->getDeclName() << O->getDeclName();
+      diag(O->getLocation(), "function to override is here",
+           DiagnosticIDs::Note);
+    }
+  }
+}