From 1e27db6c20913bf1c8b607f1eb5e899fc8f4112e Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@qt.io>
Date: Fri, 6 Dec 2019 22:03:35 +0100
Subject: Avoid using a QRegExp for trivial replacements

It's slow and we want to get rid of it. In this case,
it's just as easy to do the replacing manually using
a small loop.

Task-number: QTBUG-72587
Change-Id: I32e1cc89642bc0e5b6f500d072960cd8871e0684
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
---
 src/corelib/io/qprocess_win.cpp | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/corelib/io/qprocess_win.cpp b/src/corelib/io/qprocess_win.cpp
index 05af5a5aee..1527cf93ed 100644
--- a/src/corelib/io/qprocess_win.cpp
+++ b/src/corelib/io/qprocess_win.cpp
@@ -49,7 +49,6 @@
 #include <qelapsedtimer.h>
 #include <qfileinfo.h>
 #include <qrandom.h>
-#include <qregexp.h>
 #include <qwineventnotifier.h>
 #include <private/qsystemlibrary_p.h>
 #include <private/qthread_p.h>
@@ -398,7 +397,17 @@ static QString qt_create_commandline(const QString &program, const QStringList &
     for (int i=0; i<arguments.size(); ++i) {
         QString tmp = arguments.at(i);
         // Quotes are escaped and their preceding backslashes are doubled.
-        tmp.replace(QRegExp(QLatin1String("(\\\\*)\"")), QLatin1String("\\1\\1\\\""));
+        int index = tmp.indexOf(QLatin1Char('"'));
+        while (index >= 0) {
+            // Escape quote
+            tmp.insert(index++, QLatin1Char('\\'));
+            // Double preceding backslashes (ignoring the one we just inserted)
+            for (int i = index - 2 ; i >= 0 && tmp.at(i) == QLatin1Char('\\') ; --i) {
+                tmp.insert(i, QLatin1Char('\\'));
+                index++;
+            }
+            index = tmp.indexOf(QLatin1Char('"'), index + 1);
+        }
         if (tmp.isEmpty() || tmp.contains(QLatin1Char(' ')) || tmp.contains(QLatin1Char('\t'))) {
             // The argument must not end with a \ since this would be interpreted
             // as escaping the quote -- rather put the \ behind the quote: e.g.
-- 
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