Fix warning 'unused-lambda-capture'.

src/app/puzzle/vpmainwindow.cpp

@@ -61,6 +61,7 @@
 #include "dialogs/dialogsavemanuallayout.h"
 #include "../vdxf/libdxfrw/drw_base.h"
 #include "../vmisc/dialogs/dialogselectlanguage.h"
+#include "../vmisc/lambdaconstants.h"
 
 #if QT_VERSION < QT_VERSION_CHECK(5, 12, 0)
 #include "../vmisc/backport/qscopeguard.h"
@@ -775,8 +776,8 @@ void VPMainWindow::InitPropertyTabCurrentPiece()
     ui->comboBoxTranslateUnit->setCurrentIndex(0);
     ui->comboBoxTranslateUnit->blockSignals(false);
 
-    int minTranslate = -1000;
-    int maxTranslate = 1000;
+    const int minTranslate = -1000;
+    const int maxTranslate = 1000;
 
     ui->doubleSpinBoxCurrentPieceBoxPositionX->setMinimum(
                 UnitConvertor(minTranslate, Unit::Cm, m_oldPieceTranslationUnit));
@@ -791,7 +792,7 @@ void VPMainWindow::InitPropertyTabCurrentPiece()
     ui->doubleSpinBoxCurrentPieceBoxPositionY->setValue(0);
 
     connect(ui->comboBoxTranslateUnit, QOverload<int>::of(&QComboBox::currentIndexChanged), this,
-            [this, minTranslate, maxTranslate]()
+            [this V_LAMBDA_CONSTANTS(minTranslate, maxTranslate)]()
     {
         const Unit newUnit = TranslateUnit();
         const qreal oldTranslateX = ui->doubleSpinBoxCurrentPieceBoxPositionX->value();

src/app/valentina/dialogs/vwidgetbackgroundimages.cpp

@@ -42,6 +42,7 @@
 #include "../vtools/undocommands/image/scalebackgroundimage.h"
 #include "../vtools/undocommands/image/resetbackgroundimage.h"
 #include "../vmisc/vabstractapplication.h"
+#include "../vmisc/lambdaconstants.h"
 
 #include <QMenu>
 #include <QPushButton>
@@ -844,7 +845,7 @@ void VWidgetBackgroundImages::InitImageTranslation()
     ui->doubleSpinBoxImageVerticalTranslate->setValue(0);
 
     connect(ui->comboBoxTranslateUnit, QOverload<int>::of(&QComboBox::currentIndexChanged), this,
-            [this, minTranslate, maxTranslate]()
+            [this V_LAMBDA_CONSTANTS(minTranslate, maxTranslate)]()
     {
         const Unit newUnit = CurrentTranslateUnit();
         const qreal oldTranslateX = ui->doubleSpinBoxImageHorizontalTranslate->value();
@@ -891,7 +892,7 @@ void VWidgetBackgroundImages::InitImageTranslation()
     ui->doubleSpinBoxScaleHeight->setValue(100);
 
     connect(ui->comboBoxScaleUnit, QOverload<int>::of(&QComboBox::currentIndexChanged), this,
-            [this, minScale, maxScale]()
+            [this V_LAMBDA_CONSTANTS(minScale, maxScale)]()
     {
         const enum ScaleUnit newUnit = CurrentScaleUnit();
         const qreal oldScaleWidth = ui->doubleSpinBoxScaleWidth->value();

src/libs/vmisc/lambdaconstants.h

@@ -0,0 +1,68 @@
+/************************************************************************
+ **
+ **  @file   lambdaconstants.h
+ **  @author Roman Telezhynskyi <dismine(at)gmail.com>
+ **  @date   29 1, 2022
+ **
+ **  @brief
+ **  @copyright
+ **  This source code is part of the Valentina project, a pattern making
+ **  program, whose allow create and modeling patterns of clothing.
+ **  Copyright (C) 2022 Valentina project
+ **  <https://gitlab.com/smart-pattern/valentina> All Rights Reserved.
+ **
+ **  Valentina is free software: you can redistribute it and/or modify
+ **  it under the terms of the GNU General Public License as published by
+ **  the Free Software Foundation, either version 3 of the License, or
+ **  (at your option) any later version.
+ **
+ **  Valentina is distributed in the hope that it will be useful,
+ **  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ **  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ **  GNU General Public License for more details.
+ **
+ **  You should have received a copy of the GNU General Public License
+ **  along with Valentina.  If not, see <http://www.gnu.org/licenses/>.
+ **
+ *************************************************************************/
+#ifndef LAMBDACONSTANTS_H
+#define LAMBDACONSTANTS_H
+
+/*
+    given a lambda that wants to capture two constants
+
+    const auto k1 = 1000;
+    const auto k2 = 2000;
+    int v = 0;
+
+    auto lambda = [&v, &k1, &k2]() {
+        v = k1 * k2;
+    }
+
+    Then unfortunately clang will correctly warn about unnecessary captures. And MSVC will fail to compile if you don't
+    capture.
+
+    https://stackoverflow.com/questions/52416362/unused-lambda-capture-warning-when-capture-is-actually-used
+
+    An imperfect solution is to declare the lambda using the V_LAMBDA_CONSTANTS macro.
+
+    auto lambda = [&v
+    V_LAMBDA_CONSTANTS(&k1, &k2)
+    ](){
+        v = k1 * k2;
+    }
+
+    This should work correctly. Most of the time.
+
+NOTE: There is no comma after the final capture variable before the V_LAMBDA_CONSTANTS macro. The macro is variadic and
+will work with 1 or more captures.
+*/
+#ifndef V_LAMBDA_CONSTANTS
+#if defined(Q_CC_MSVC)
+#define V_LAMBDA_CONSTANTS(...) ,__VA_ARGS__
+#else
+#define V_LAMBDA_CONSTANTS(...)
+#endif
+#endif
+
+#endif // LAMBDACONSTANTS_H

src/libs/vmisc/vmisc.pri

@@ -27,6 +27,7 @@ contains(DEFINES, APPIMAGE) {
 
 HEADERS += \
     $$PWD/compatibility.h \
+    $$PWD/lambdaconstants.h \
     $$PWD/stable.h \
     $$PWD/def.h \
     $$PWD/testpath.h \