Git: Add new files with --intent-to-add

Sometimes the file is modified after adding it, either by Qt Creator itself
or by the user.

Running Diff on such a file may look strange. Instead of showing the entire
file, it shows the diff since it was added with its initial content.

Fixes: QTCREATORBUG-23441
Change-Id: I712cc574053f39753250685aec148d2b6d7db192
Reviewed-by: André Hartmann <aha_1980@gmx.de>

src/plugins/git/gitclient.cpp

@@ -1438,10 +1438,13 @@ bool GitClient::synchronousLog(const QString &workingDirectory, const QStringLis
     }
 }
 
-bool GitClient::synchronousAdd(const QString &workingDirectory, const QStringList &files)
+bool GitClient::synchronousAdd(const QString &workingDirectory,
+                               const QStringList &files,
+                               const QStringList &extraOptions)
 {
-    return vcsFullySynchronousExec(workingDirectory, QStringList({"add"}) + files).result
-            == SynchronousProcessResponse::Finished;
+    QStringList args{"add"};
+    args += extraOptions + files;
+    return vcsFullySynchronousExec(workingDirectory, args).result == SynchronousProcessResponse::Finished;
 }
 
 bool GitClient::synchronousDelete(const QString &workingDirectory,
@@ -2890,7 +2893,7 @@ bool GitClient::addAndCommit(const QString &repositoryDirectory,
             filesToReset.removeAll(file);
             filesToAdd.append(file);
         } else if (state == AddedFile && checked) {
-            QTC_ASSERT(false, continue); // these should be untracked!
+            filesToAdd.append(file);
         } else if (state == DeletedFile && checked) {
             filesToReset.removeAll(file);
             filesToRemove.append(file);

src/plugins/git/gitclient.h

@@ -185,7 +185,8 @@ public:
     bool synchronousLog(const QString &workingDirectory, const QStringList &arguments,
                         QString *output, QString *errorMessage = nullptr,
                         unsigned flags = 0);
-    bool synchronousAdd(const QString &workingDirectory, const QStringList &files);
+    bool synchronousAdd(const QString &workingDirectory, const QStringList &files,
+                        const QStringList &extraOptions = {});
     bool synchronousDelete(const QString &workingDirectory,
                            bool force,
                            const QStringList &files);

src/plugins/git/gitplugin.cpp

@@ -1859,7 +1859,7 @@ bool GitPluginPrivate::vcsOpen(const QString & /*fileName*/)
 bool GitPluginPrivate::vcsAdd(const QString & fileName)
 {
     const QFileInfo fi(fileName);
-    return m_gitClient.synchronousAdd(fi.absolutePath(), {fi.fileName()});
+    return m_gitClient.synchronousAdd(fi.absolutePath(), {fi.fileName()}, {"--intent-to-add"});
 }
 
 bool GitPluginPrivate::vcsDelete(const QString & fileName)