loplugin:ostr: Rewrite some uses of O[U]String to use ""_ostr/u""_ustr literals

This is a first cut at rewriting uses of OUString constructed from u"..." as
u"..."_ustr.  It covers the same changes as
<https://gerrit.libreoffice.org/c/core/+/155412/6/> "WIP: Delete OUString UTF-16
string literal ctor/assignment op", but does so with automatic rewriting (see
e0c33ec15f53a01fa3ee07489871bbe09bb5c9c3 "loplugin:ostr: automatic rewrite",
plus a handful of 002b0a9d5793e07609f953b9961b04bcab7a7e3f "loplugin:ostr:
manual modifications" where automatic rewriting wasn't set up to handle macro
bodies).

The compilation-time impact of all those changes appears to be negligible:  For
some Windows build of mine, just touching the files that would be affected by
002b0a9d5793e07609f953b9961b04bcab7a7e3f and
e0c33ec15f53a01fa3ee07489871bbe09bb5c9c3 (but without actually applying those
changes yet) and doing `time /opt/lo/bin/make -O check screenshot PKGFORMAT=
gb_SUPPRESS_TESTS=x`, three times in a row reported sample real times of

21m15.438s  23m17.840s  23m41.529s

and repeating all that with the two changes actually applied reported sample
real times of

22m43.547s  21m42.687s  23m1.813s

The plugin itself is already prepared to do further rewrites (see the TODOs),
which will be done in follow-up commits.

Change-Id: I408ecf056dce1b9da683d7c377b8d9058df1558d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/157676
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 286 insertions, 0 deletions

diff --git a/compilerplugins/clang/ostr.cxx b/compilerplugins/clang/ostr.cxx
new file mode 100644
index 000000000000..13fd5df0b29a
--- /dev/null
+++ b/compilerplugins/clang/ostr.cxx
@@ -0,0 +1,286 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * 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 <cassert>
+#include <set>
+#include <stack>
+
+#include "check.hxx"
+#include "compat.hxx"
+#include "plugin.hxx"
+
+// Rewrite some uses of O[U]String to use ""_ostr/u""_ustr literals.
+
+namespace
+{
+class Ostr : public loplugin::FilteringRewritePlugin<Ostr>
+{
+public:
+    explicit Ostr(loplugin::InstantiationData const& data)
+        : FilteringRewritePlugin(data)
+    {
+    }
+
+    // Needed so that e.g.
+    //
+    //   struct S { OUString s; };
+    //   S s = {u"foo"};
+    //
+    // is caught:
+    bool shouldVisitImplicitCode() const { return true; }
+
+    void run() override
+    {
+        if (compiler.getLangOpts().CPlusPlus)
+        {
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+        }
+    }
+
+    bool TraverseParmVarDecl(ParmVarDecl* decl)
+    {
+        // Otherwise,
+        //
+        //   struct S { void f(int = 0); };
+        //   void S::f(int) {}
+        //
+        // would visit the default argument twice:
+        if (decl->hasDefaultArg() && !decl->hasUninstantiatedDefaultArg()
+            && !decl->hasUnparsedDefaultArg() && !defaultArgs_.insert(decl->getDefaultArg()).second)
+        {
+            return true;
+        }
+        return RecursiveASTVisitor::TraverseParmVarDecl(decl);
+    }
+
+    bool TraverseCXXFunctionalCastExpr(CXXFunctionalCastExpr* expr)
+    {
+        functionalCasts_.push(expr);
+        auto const ret = RecursiveASTVisitor::TraverseCXXFunctionalCastExpr(expr);
+        functionalCasts_.pop();
+        return ret;
+    }
+
+    bool VisitCXXConstructExpr(CXXConstructExpr const* expr)
+    {
+        if (ignoreLocation(expr))
+        {
+            return true;
+        }
+        if (!loplugin::DeclCheck(expr->getConstructor()->getParent())
+                 .Class("OUString")
+                 .Namespace("rtl")
+                 .GlobalNamespace())
+        {
+            return true;
+        }
+        if (expr->getNumArgs() != 2)
+        {
+            return true;
+        }
+        if (!loplugin::TypeCheck(expr->getArg(1)->getType())
+                 .Struct("Dummy")
+                 .Namespace("libreoffice_internal")
+                 .Namespace("rtl")
+                 .GlobalNamespace())
+        {
+            return true;
+        }
+        auto const e2 = dyn_cast<clang::StringLiteral>(expr->getArg(0)->IgnoreParenImpCasts());
+        if (e2 == nullptr)
+        {
+            return true;
+        }
+        if (!(compat::isOrdinary(e2) || e2->isUTF16()))
+        {
+            assert(!e2->isUTF8()); //TODO
+            return true;
+        }
+        auto const temp = isa<CXXTemporaryObjectExpr>(expr)
+                          || (!functionalCasts_.empty()
+                              && functionalCasts_.top()->getSubExpr()->IgnoreImplicit() == expr);
+        auto const e1 = temp ? static_cast<Expr const*>(expr) : static_cast<Expr const*>(e2);
+        auto l1 = e1->getBeginLoc();
+        auto l2 = e2->getBeginLoc();
+        auto l3 = e2->getEndLoc();
+        auto l4 = e1->getEndLoc();
+        while (compiler.getSourceManager().isMacroArgExpansion(l1)
+               && compiler.getSourceManager().isMacroArgExpansion(l2)
+               && compiler.getSourceManager().isMacroArgExpansion(l3)
+               && compiler.getSourceManager().isMacroArgExpansion(l4))
+        //TODO: check all four locations are part of the same macro argument expansion
+        {
+            l1 = compiler.getSourceManager().getImmediateMacroCallerLoc(l1);
+            l2 = compiler.getSourceManager().getImmediateMacroCallerLoc(l2);
+            l3 = compiler.getSourceManager().getImmediateMacroCallerLoc(l3);
+            l4 = compiler.getSourceManager().getImmediateMacroCallerLoc(l4);
+        }
+        if (!locs_.insert(l1).second)
+        {
+            return true;
+        }
+        auto const macroBegin = l2.isMacroID()
+                                && Lexer::isAtStartOfMacroExpansion(l2, compiler.getSourceManager(),
+                                                                    compiler.getLangOpts());
+        if (macroBegin)
+        {
+            l2 = compiler.getSourceManager().getImmediateMacroCallerLoc(l2);
+        }
+        auto const macroEnd = l3.isMacroID()
+                              && Lexer::isAtEndOfMacroExpansion(l3, compiler.getSourceManager(),
+                                                                compiler.getLangOpts());
+        if (macroEnd)
+        {
+            l3 = compiler.getSourceManager().getImmediateMacroCallerLoc(l3);
+        }
+        if (!temp)
+        {
+            l1 = l2;
+            l4 = l3;
+        }
+        if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(l1)))
+        {
+            return true;
+        }
+        if (!(e2->isUTF16() || compiler.getDiagnosticOpts().VerifyDiagnostics))
+        {
+            //TODO: Leave rewriting these uses of ordinary string literals for later (but already
+            // cover them when verifying CompilerTest_compilerplugins_clang):
+            return true;
+        }
+        if (rewriter != nullptr && isSpellingRange(l1, l2) && isSpellingRange(l3, l4))
+        {
+            l3 = l3.getLocWithOffset(
+                Lexer::MeasureTokenLength(l3, compiler.getSourceManager(), compiler.getLangOpts()));
+            l4 = l4.getLocWithOffset(
+                Lexer::MeasureTokenLength(l4, compiler.getSourceManager(), compiler.getLangOpts()));
+            if ((e2->isUTF16() ? removeText(l1, delta(l1, l2))
+                               : replaceText(l1, delta(l1, l2), macroBegin ? "u\"\" " : "u"))
+                && replaceText(l3, delta(l3, l4), macroEnd ? " \"\"_ustr" : "_ustr"))
+            {
+                return true;
+            }
+        }
+        report(DiagnosticsEngine::Warning,
+               "use a _ustr user-defined string literal instead of constructing an instance of %0 "
+               "from %select{an ordinary|a UTF-16}1 string literal",
+               expr->getExprLoc())
+            << expr->getType().getLocalUnqualifiedType() << e2->isUTF16() << expr->getSourceRange();
+        return true;
+    }
+
+    bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr const* expr)
+    {
+        if (ignoreLocation(expr))
+        {
+            return true;
+        }
+        if (expr->getOperator() != OO_Equal)
+        {
+            return true;
+        }
+        if (!loplugin::TypeCheck(expr->getArg(0)->getType())
+                 .Class("OUString")
+                 .Namespace("rtl")
+                 .GlobalNamespace())
+        {
+            return true;
+        }
+        auto const e2 = dyn_cast<clang::StringLiteral>(expr->getArg(1)->IgnoreParenImpCasts());
+        if (e2 == nullptr)
+        {
+            return true;
+        }
+        if (!e2->isUTF16())
+        {
+            return true;
+        }
+        if (rewriter != nullptr)
+        {
+            if (insertTextAfterToken(e2->getEndLoc(), "_ustr"))
+            {
+                return true;
+            }
+        }
+        report(DiagnosticsEngine::Warning,
+               "use a _ustr user-defined string literal instead of assigning from a UTF-16 string"
+               " literal",
+               expr->getExprLoc())
+            << expr->getSourceRange();
+        return true;
+    }
+
+    bool VisitCXXMemberCallExpr(CXXMemberCallExpr const* expr)
+    {
+        if (ignoreLocation(expr))
+        {
+            return true;
+        }
+        if (!loplugin::DeclCheck(expr->getMethodDecl()).Operator(OO_Equal))
+        {
+            return true;
+        }
+        if (!loplugin::TypeCheck(expr->getObjectType())
+                 .Class("OUString")
+                 .Namespace("rtl")
+                 .GlobalNamespace())
+        {
+            return true;
+        }
+        auto const e2 = dyn_cast<clang::StringLiteral>(expr->getArg(0)->IgnoreParenImpCasts());
+        if (e2 == nullptr)
+        {
+            return true;
+        }
+        if (!e2->isUTF16())
+        {
+            return true;
+        }
+        if (rewriter != nullptr)
+        {
+            //TODO
+        }
+        report(DiagnosticsEngine::Warning,
+               "use a _ustr user-defined string literal instead of assigning from a UTF-16 string"
+               " literal",
+               expr->getExprLoc())
+            << expr->getSourceRange();
+        return true;
+    }
+
+private:
+    bool isSpellingRange(SourceLocation loc1, SourceLocation loc2)
+    {
+        if (!SourceLocation::isPairOfFileLocations(loc1, loc2))
+        {
+            return false;
+        }
+        if (compiler.getSourceManager().getFileID(loc1)
+            != compiler.getSourceManager().getFileID(loc2))
+        {
+            return false;
+        }
+        return loc1 <= loc2;
+    }
+
+    unsigned delta(SourceLocation loc1, SourceLocation loc2)
+    {
+        return compiler.getSourceManager().getDecomposedLoc(loc2).second
+               - compiler.getSourceManager().getDecomposedLoc(loc1).second;
+    }
+
+    std::set<Expr const*> defaultArgs_;
+    std::stack<CXXFunctionalCastExpr const*> functionalCasts_;
+    std::set<SourceLocation> locs_;
+};
+
+loplugin::Plugin::Registration<Ostr> X("ostr", true);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */