Bug 1324239 - Refactor the clang plugin; r=mystor

This patch mostly just splits up clang-plugin.cpp into separate files for
different classes or helpers.

build/clang-plugin/ExplicitOperatorBoolChecker.cpp

@@ -0,0 +1,36 @@
+/* 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 "ExplicitOperatorBoolChecker.h"
+#include "CustomMatchers.h"
+
+void ExplicitOperatorBoolChecker::registerMatcher(MatchFinder& AstMatcher) {
+  // Older clang versions such as the ones used on the infra recognize these
+  // conversions as 'operator _Bool', but newer clang versions recognize these
+  // as 'operator bool'.
+  AstMatcher.addMatcher(
+      cxxMethodDecl(anyOf(hasName("operator bool"), hasName("operator _Bool")))
+          .bind("node"),
+      this);
+}
+
+void ExplicitOperatorBoolChecker::run(
+    const MatchFinder::MatchResult &Result) {
+  DiagnosticsEngine &Diag = Result.Context->getDiagnostics();
+  unsigned ErrorID = Diag.getDiagnosticIDs()->getCustomDiagID(
+      DiagnosticIDs::Error, "bad implicit conversion operator for %0");
+  unsigned NoteID = Diag.getDiagnosticIDs()->getCustomDiagID(
+      DiagnosticIDs::Note, "consider adding the explicit keyword to %0");
+  const CXXConversionDecl *Method =
+      Result.Nodes.getNodeAs<CXXConversionDecl>("node");
+  const CXXRecordDecl *Clazz = Method->getParent();
+
+  if (!Method->isExplicitSpecified() &&
+      !MozChecker::hasCustomAnnotation(Method, "moz_implicit") &&
+      !ASTIsInSystemHeader(Method->getASTContext(), *Method) &&
+      isInterestingDeclForImplicitConversion(Method)) {
+    Diag.Report(Method->getLocStart(), ErrorID) << Clazz;
+    Diag.Report(Method->getLocStart(), NoteID) << "'operator bool'";
+  }
+}