loplugin:salunicodeliteral

For the c-char in the u'...' literal, the preceding commits consistently use:

* a simple-escape-sequence if the original code already used one
* \0 for U+0000
* the (\ escaped, for ' and \) source character matching U+0020..7E (even if it
is not a basic source character)
* a consistently four-digit hexadecimal-escape-sequence otherwise, \xNNNN

For non-surrogate code points, the last case could probably also use \uNNNN
universal-character-names.  However, for one, it isn't quite clear to me whether
conversion of such to members of the execution chacacter set in character
literals (in translation phase 5) is implementation-specific.  And for another,
the current C++ standard references the dated (no pun intended) ISO/IEC
10646-1:1993 specification, rather than the current ISO/IEC 10646:2014, and
requires that a universal-characrer-name designate a character with a specific
"character short name in ISO/IEC 10646", but I do not find a specification of a
"short name" in ISO/IEC 10646:2014 and don't have access to ISO/IEC
10646-1:1993, so am not sure whether that would e.g. cover noncharacters like
U+FFFF.

(The only exception is one occurrence of u'\x6C' in bestFitOpenSymbolToMSFont,
filter/source/msfilter/util.cxx, where it is clear from the context that the
value denotes neither a Unicode code point nor a UTF-16 code unit, but rather an
index into the Wingdings font glyph table.)

Change-Id: If36b94168428ba1e05977c370aceaa7e90131e90

3 files changed, 142 insertions, 0 deletions

diff --git a/compilerplugins/clang/salunicodeliteral.cxx b/compilerplugins/clang/salunicodeliteral.cxx
new file mode 100644
index 000000000000..6b03156b55e7
--- /dev/null
+++ b/compilerplugins/clang/salunicodeliteral.cxx
@@ -0,0 +1,86 @@
+/* -*- 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 "check.hxx"
+#include "plugin.hxx"
+
+namespace {
+
+bool isAsciiCharacterLiteral(Expr const * expr) {
+    if (auto const e = dyn_cast<CharacterLiteral>(expr)) {
+        return e->getKind() == CharacterLiteral::Ascii;
+    }
+    return false;
+}
+
+class Visitor final:
+    public RecursiveASTVisitor<Visitor>, public loplugin::Plugin
+{
+public:
+    explicit Visitor(InstantiationData const & data): Plugin(data) {}
+
+    bool VisitCXXStaticCastExpr(CXXStaticCastExpr const * expr) {
+        check(expr);
+        return true;
+    }
+
+    bool VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr const * expr) {
+        check(expr);
+        return true;
+    }
+
+    bool VisitCStyleCastExpr(CStyleCastExpr const * expr) {
+        check(expr);
+        return true;
+    }
+
+private:
+    void run() override {
+        if (compiler.getLangOpts().CPlusPlus
+            && compiler.getPreprocessor().getIdentifierInfo(
+                "LIBO_INTERNAL_ONLY")->hasMacroDefinition())
+        {
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+        }
+    }
+
+    void check(ExplicitCastExpr const * expr) {
+        if (ignoreLocation(expr)
+            || isInUnoIncludeFile(expr->getExprLoc())
+                //TODO: '#ifdef LIBO_INTERNAL_ONLY' within UNO include files
+            || !(loplugin::TypeCheck(expr->getTypeAsWritten())
+                 .Typedef("sal_Unicode").GlobalNamespace()))
+        {
+            return;
+        }
+        auto const e1 = expr->getSubExprAsWritten();
+        auto const loc = e1->getLocStart();
+        if (loc.isMacroID()
+            && compiler.getSourceManager().isAtStartOfImmediateMacroExpansion(
+                loc))
+        {
+            return;
+        }
+        auto const e2 = e1->IgnoreParenImpCasts();
+        if (isAsciiCharacterLiteral(e2) || isa<IntegerLiteral>(e2)) {
+            report(
+                DiagnosticsEngine::Warning,
+                ("in LIBO_INTERNAL_ONLY code, replace literal cast to %0 with a"
+                 " u'...' char16_t character literal"),
+                e2->getExprLoc())
+                << expr->getTypeAsWritten() << expr->getSourceRange();
+        }
+    }
+};
+
+static loplugin::Plugin::Registration<Visitor> reg("salunicodeliteral");
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/compilerplugins/clang/test/salunicodeliteral.cxx b/compilerplugins/clang/test/salunicodeliteral.cxx
new file mode 100644
index 000000000000..1daf9df0acb9
--- /dev/null
+++ b/compilerplugins/clang/test/salunicodeliteral.cxx
@@ -0,0 +1,39 @@
+/* -*- 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 "sal/config.h"
+
+#include "sal/types.h"
+
+#include "salunicodeliteral.hxx"
+
+#define TEST1 'x'
+#define TEST2 sal_Unicode('x')
+
+namespace {
+
+void f(sal_Unicode) {}
+
+}
+
+void test() {
+    f(sal_Unicode('x')); // expected-error {{in LIBO_INTERNAL_ONLY code, replace literal cast to 'sal_Unicode' (aka 'char16_t') with a u'...' char16_t character literal [loplugin:salunicodeliteral]}}
+    f(static_cast<sal_Unicode>('x')); // expected-error {{in LIBO_INTERNAL_ONLY code, replace literal cast to 'sal_Unicode' (aka 'char16_t') with a u'...' char16_t character literal [loplugin:salunicodeliteral]}}
+    f(static_cast<sal_Unicode const>('x')); // expected-error {{in LIBO_INTERNAL_ONLY code, replace literal cast to 'const sal_Unicode' (aka 'const char16_t') with a u'...' char16_t character literal [loplugin:salunicodeliteral]}}
+    f((sal_Unicode) 'x'); // expected-error {{in LIBO_INTERNAL_ONLY code, replace literal cast to 'sal_Unicode' (aka 'char16_t') with a u'...' char16_t character literal [loplugin:salunicodeliteral]}}
+    f(sal_Unicode(('x'))); // expected-error {{in LIBO_INTERNAL_ONLY code, replace literal cast to 'sal_Unicode' (aka 'char16_t') with a u'...' char16_t character literal [loplugin:salunicodeliteral]}}
+    f(sal_Unicode(120)); // expected-error {{in LIBO_INTERNAL_ONLY code, replace literal cast to 'sal_Unicode' (aka 'char16_t') with a u'...' char16_t character literal [loplugin:salunicodeliteral]}}
+    f(sal_Unicode(TEST1));
+    f(TEST2); // expected-error {{in LIBO_INTERNAL_ONLY code, replace literal cast to 'sal_Unicode' (aka 'char16_t') with a u'...' char16_t character literal [loplugin:salunicodeliteral]}}
+    char c = 'x';
+    f(sal_Unicode(c));
+    f(char16_t('x'));
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/compilerplugins/clang/test/salunicodeliteral.hxx b/compilerplugins/clang/test/salunicodeliteral.hxx
new file mode 100644
index 000000000000..f4491c72397f
--- /dev/null
+++ b/compilerplugins/clang/test/salunicodeliteral.hxx
@@ -0,0 +1,17 @@
+/* -*- 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/.
+ */
+
+#ifndef INCLUDED_COMPILERPLUGINS_CLANG_TEST_SALUNICODELITERAL_HXX
+#define INCLUDED_COMPILERPLUGINS_CLANG_TEST_SALUNICODELITERAL_HXX
+
+void test();
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */