Plugin to warn about/fix verriding functions not marked SAL_OVERRIDE

Change-Id: I1d49aa9ad238cd5bd2e04479c2eb916f010417df

compilerplugins/clang/saloverride.cxx

+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * 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 <algorithm>
+#include <cassert>
+#include <limits>
+#include <set>
+
+#include "clang/AST/Attr.h"
+
+#include "compat.hxx"
+#include "plugin.hxx"
+
+namespace {
+
+class SalOverride:
+    public RecursiveASTVisitor<SalOverride>, public loplugin::RewritePlugin
+{
+public:
+    explicit SalOverride(InstantiationData const & data): RewritePlugin(data) {}
+
+    virtual void run() override
+    { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    bool VisitCXXMethodDecl(CXXMethodDecl const * decl);
+
+private:
+    std::set<SourceLocation> insertions_;
+};
+
+bool SalOverride::VisitCXXMethodDecl(CXXMethodDecl const * decl) {
+    // As a heuristic, ignore declarations where the name is spelled out in an
+    // ignored location; that e.g. handles uses of the Q_OBJECT macro from
+    // external QtCore/qobjectdefs.h:
+    if (ignoreLocation(decl) || !compat::isFirstDecl(*decl)
+        || decl->begin_overridden_methods() == decl->end_overridden_methods()
+        || decl->hasAttr<OverrideAttr>() || isa<CXXDestructorDecl>(decl)
+        || ignoreLocation(
+            compiler.getSourceManager().getSpellingLoc(
+                decl->getNameInfo().getLoc())))
+    {
+        return true;
+    }
+#if LO_COMPILERPLUGINS_CLANG_COMPAT_HAVE_isAtEndOfImmediateMacroExpansion
+    if (rewriter != nullptr) {
+        // In  void MACRO(...);  getSourceRange().getEnd() would (erroneously?)
+        // point at "MACRO" rather than ")", so make the loop always terminate
+        // at the first ";" or "{" instead of getSourceRange().getEnd():
+        unsigned parens = 0;
+        bool seenSpace = false;
+        //TODO: Whether to add a space after the inserted "SAL_OVERRIDE" should
+        // depend on the following token at the spelling location where
+        // "SAL_OVERRIDE" is inserted, not on the following token in the fully-
+        // macro-expanded view:
+        bool addSpace;
+        SourceLocation loc;
+        for (SourceLocation l(decl->getSourceRange().getBegin());;) {
+            SourceLocation sl(compiler.getSourceManager().getSpellingLoc(l));
+            unsigned n = Lexer::MeasureTokenLength(
+                sl, compiler.getSourceManager(), compiler.getLangOpts());
+            StringRef s(compiler.getSourceManager().getCharacterData(sl), n);
+            //TODO: Looks like a Clang bug that in some cases like
+            // (filter/source/svg/svgexport.cxx)
+            //
+            // #define TEXT_FIELD_GET_CLASS_NAME_METHOD( class_name ) \
+            // virtual OUString getClassName() const                  \
+            // {                                                      \
+            //     static const char className[] = #class_name;       \
+            //     return OUString( className );                      \
+            // }
+            //
+            // TEXT_FIELD_GET_CLASS_NAME_METHOD( TextField )
+            //
+            // where "\<NL>" is followed directly by a real token without
+            // intervening whitespace, tokens "\<NL>virtual" and "\<NL>{" are
+            // reported:
+            if (s.startswith("\\\n")) {
+                s = s.drop_front(2);
+            }
+            if (parens == 0) {
+                if (s == "=" || s == "{") {
+                    if (!seenSpace) {
+                        addSpace = true;
+                    }
+                    break;
+                }
+                if (s == ";") {
+                    break;
+                }
+            }
+            if (s == "(") {
+                assert(parens < std::numeric_limits<unsigned>::max());
+                ++parens;
+            } else if (s == ")") {
+                assert(parens != 0);
+                --parens;
+            }
+            if (s.empty()) {
+                if (!seenSpace) {
+                    addSpace = false;
+                }
+                seenSpace = true;
+            } else if (s.startswith("/*") || s.startswith("//") || s == "\\") {
+                if (!seenSpace) {
+                    addSpace = true;
+                }
+                seenSpace = true;
+            } else {
+                seenSpace = false;
+                addSpace = false;
+                loc = sl;
+            }
+            if (l.isMacroID()
+                && compiler.getSourceManager().isAtEndOfImmediateMacroExpansion(
+                    l, &l))
+            {
+                n = Lexer::MeasureTokenLength(
+                    l, compiler.getSourceManager(), compiler.getLangOpts());
+            }
+            l = l.getLocWithOffset(std::max<unsigned>(n, 1));
+        }
+        assert(loc.isValid());
+        if (!insertions_.insert(loc).second
+            || insertTextAfterToken(
+                loc, addSpace ? " SAL_OVERRIDE " : " SAL_OVERRIDE"))
+        {
+            return true;
+        }
+    }
+#endif
+    report(
+        DiagnosticsEngine::Warning,
+        ("overriding virtual function declaration not marked 'override' (aka"
+         " 'SAL_OVERRIDE')"),
+        decl->getLocation())
+        << decl->getSourceRange();
+    for (auto i = decl->begin_overridden_methods();
+         i != decl->end_overridden_methods(); ++i)
+    {
+        report(
+            DiagnosticsEngine::Note, "overridden declaration is here",
+            (*i)->getLocation())
+            << (*i)->getSourceRange();
+    }
+    return true;
+}
+
+loplugin::Plugin::Registration<SalOverride> X("saloverride", true);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */