Fix compilation issues with C++17

Testable on Linux/macOS by changing c++14 to c++1z in qtcreator.pri.
Testable with latest MSVC2017 by setting _CL_=/std:c++17.

unary_function, binary_function, and a few other things that were
deprecated are removed in C++17.
std::string got a non-const overload for its "data" member function,
so we cannot create a function pointer on it without specifying its
type. Use std::declval instead (though it requires a default constructor
for the type).

MSVC seems to have an issue with Utils::transform for std::vector
(used in Nim plugin), but that looks like a compiler issue.

Change-Id: I94f9a93d591d55b610f86fabfc618158927d6221
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

1 files changed, 16 insertions, 3 deletions

diff --git a/src/plugins/qmljseditor/qmljsfindreferences.cpp b/src/plugins/qmljseditor/qmljsfindreferences.cpp
index 7806d9c385..af2750de0c 100644
--- a/src/plugins/qmljseditor/qmljsfindreferences.cpp
+++ b/src/plugins/qmljseditor/qmljsfindreferences.cpp
@@ -683,7 +683,7 @@ static QString matchingLine(unsigned position, const QString &source)
     return source.mid(start, end - start);
 }
 
-class ProcessFile: public std::unary_function<QString, QList<FindReferences::Usage> >
+class ProcessFile
 {
     ContextPtr context;
     typedef FindReferences::Usage Usage;
@@ -692,6 +692,10 @@ class ProcessFile: public std::unary_function<QString, QList<FindReferences::Usa
     QFutureInterface<Usage> *future;
 
 public:
+    // needed by QtConcurrent
+    using argument_type = const QString &;
+    using result_type = QList<Usage>;
+
     ProcessFile(const ContextPtr &context,
                 QString name,
                 const ObjectValue *scope,
@@ -721,7 +725,7 @@ public:
     }
 };
 
-class SearchFileForType: public std::unary_function<QString, QList<FindReferences::Usage> >
+class SearchFileForType
 {
     ContextPtr context;
     typedef FindReferences::Usage Usage;
@@ -730,6 +734,10 @@ class SearchFileForType: public std::unary_function<QString, QList<FindReference
     QFutureInterface<Usage> *future;
 
 public:
+    // needed by QtConcurrent
+    using argument_type = const QString &;
+    using result_type = QList<Usage>;
+
     SearchFileForType(const ContextPtr &context,
                       QString name,
                       const ObjectValue *scope,
@@ -759,12 +767,17 @@ public:
     }
 };
 
-class UpdateUI: public std::binary_function<QList<FindReferences::Usage> &, QList<FindReferences::Usage>, void>
+class UpdateUI
 {
     typedef FindReferences::Usage Usage;
     QFutureInterface<Usage> *future;
 
 public:
+    // needed by QtConcurrent
+    using first_argument_type = QList<Usage> &;
+    using second_argument_type = const QList<Usage> &;
+    using result_type = void;
+
     UpdateUI(QFutureInterface<Usage> *future): future(future) {}
 
     void operator()(QList<Usage> &, const QList<Usage> &usages)