C++: Avoid inline namespaces in generated code

Task-number: QTCREATORBUG-16086
Change-Id: Ic2f3fd38ae6cc93725bc214c24320f40a0a519a8
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/cplusplus/LookupContext.cpp

@@ -230,6 +230,32 @@ static bool symbolIdentical(Symbol *s1, Symbol *s2)
     return QByteArray(s1->fileName()) == QByteArray(s2->fileName());
 }
 
+static const Name *toName(const QList<const Name *> &names, Control *control)
+{
+    const Name *n = 0;
+    for (int i = names.size() - 1; i >= 0; --i) {
+        if (! n)
+            n = names.at(i);
+        else
+            n = control->qualifiedNameId(names.at(i), n);
+    }
+
+    return n;
+}
+
+static bool isInlineNamespace(ClassOrNamespace *con, const Name *name)
+{
+    const QList<LookupItem> items = con->find(name);
+    if (!items.isEmpty()) {
+        if (const Symbol *declaration = items.first().declaration() ) {
+            if (const Namespace *ns = declaration->asNamespace())
+                return ns->isInline();
+        }
+    }
+
+    return false;
+}
+
 const Name *LookupContext::minimalName(Symbol *symbol, ClassOrNamespace *target, Control *control)
 {
     const Name *n = 0;
@@ -245,8 +271,17 @@ const Name *LookupContext::minimalName(Symbol *symbol, ClassOrNamespace *target,
         if (target) {
             const QList<LookupItem> tresults = target->lookup(n);
             foreach (const LookupItem &tr, tresults) {
-                if (symbolIdentical(tr.declaration(), symbol))
-                    return n;
+                if (symbolIdentical(tr.declaration(), symbol)) {
+                    // eliminate inline namespaces
+                    QList<const Name *> minimal = names.mid(i);
+                    for (int i = minimal.size() - 2; i >= 0; --i) {
+                        const Name *candidate = toName(minimal.mid(0, i + 1), control);
+                        if (isInlineNamespace(target, candidate))
+                            minimal.removeAt(i);
+                    }
+
+                    return toName(minimal, control);
+                }
             }
         }
     }

tests/auto/cplusplus/lookup/tst_lookup.cpp

@@ -32,6 +32,7 @@
 #include <cplusplus/Literals.h>
 #include <cplusplus/LookupContext.h>
 #include <cplusplus/Name.h>
+#include <cplusplus/NamePrettyPrinter.h>
 #include <cplusplus/Overview.h>
 #include <cplusplus/ResolveExpression.h>
 #include <cplusplus/Symbols.h>
@@ -99,6 +100,9 @@ private slots:
     void templates_3();
     void templates_4();
     void templates_5();
+
+    void minimalname_data();
+    void minimalname();
 };
 
 void tst_Lookup::base_class_defined_1()
@@ -631,5 +635,47 @@ void tst_Lookup::templates_5()
     QVERIFY(doc->diagnosticMessages().isEmpty());
 }
 
+void tst_Lookup::minimalname_data()
+{
+    QTest::addColumn<QByteArray>("source");
+    QTest::addColumn<int>("index");
+
+    QTest::newRow("inlineNamespace1")
+            << QByteArray("namespace std { inline namespace __cxx11 { class string{}; } }\n")
+            << 0;
+
+    // This case is extracted from libstdc++ 5.4.0.
+    // The inline namespace is re-opened as non-inline, which is not standard
+    // compliant. However, gcc does this and clang only issues a warning.
+    QTest::newRow("inlineNamespace2")
+            << QByteArray("namespace std { inline namespace __cxx11 {} }\n"
+                          "namespace std { namespace __cxx11 { class string{}; } }\n")
+            << 1;
+}
+
+void tst_Lookup::minimalname()
+{
+    QFETCH(QByteArray, source);
+    QFETCH(int, index);
+
+    Document::Ptr doc = Document::create("minimalname");
+    doc->setUtf8Source(source);
+    doc->parse();
+    doc->check();
+
+    Snapshot snapshot;
+    snapshot.insert(doc);
+    LookupContext ctx(doc, snapshot);
+    Control control;
+    Symbol *symbol = doc->globalSymbolAt(unsigned(index))
+            ->asNamespace()->memberAt(0)->asNamespace()->memberAt(0);
+
+    const Name *minimalName = LookupContext::minimalName(symbol, ctx.globalNamespace(), &control);
+
+    Overview oo;
+    const QString minimalNameAsString = NamePrettyPrinter(&oo)(minimalName);
+    QCOMPARE(minimalNameAsString, QString::fromUtf8("std::string"));
+}
+
 QTEST_APPLESS_MAIN(tst_Lookup)
 #include "tst_lookup.moc"