Highlight the warning results differently to clearly separate them visually from the normal output.

src/backends/maxima/maximaexpression.cpp

 /*
     SPDX-License-Identifier: GPL-2.0-or-later
     SPDX-FileCopyrightText: 2009-2012 Alexander Rieder <alexanderrieder@gmail.com>
-    SPDX-FileCopyrightText: 2017-2021 by Alexander Semke (alexander.semke@web.de)
+    SPDX-FileCopyrightText: 2017-2022 by Alexander Semke (alexander.semke@web.de)
 */
 
 #include "maximaexpression.h"
@@ -228,7 +228,12 @@ bool MaximaExpression::parseOutput(QString& out)
             //"\nrat: replaced 7.5 by 15/2 = 7.5\n<cantor-result><cantor-text>\n(%o2) 15/2\n</cantor-text></cantor-result>\n<cantor-prompt>(%i3) </cantor-prompt>\n".
             //In such cases we just add a new text result with the warning.
             qDebug() << "warning: " << errorContent;
-            addResult(new Cantor::TextResult(errorContent.trimmed()));
+            auto* result = new Cantor::TextResult(errorContent.trimmed());
+
+            //the output of tex() function is also placed outside of the result section, don't treat it as a warning
+            if (!command().remove(QLatin1Char(' ')).startsWith(QLatin1String("tex(")))
+                result->setIsWarning(true);
+            addResult(result);
         }
     }
 

src/backends/maxima/testmaxima.cpp

 /*
     SPDX-License-Identifier: GPL-2.0-or-later
     SPDX-FileCopyrightText: 2009 Alexander Rieder <alexanderrieder@gmail.com>
+    SPDX-FileCopyrightText: 2018-2022 by Alexander Semke (alexander.semke@web.de)
 */
 
 #include "testmaxima.h"
@@ -107,7 +108,7 @@ void TestMaxima::testInvalidSyntax()
     QVERIFY( e->status()==Cantor::Expression::Error );
 }
 
-void TestMaxima::testWarning()
+void TestMaxima::testWarning01()
 {
     auto* e = evalExp( QLatin1String("rat(0.75*10)") );
 
@@ -116,12 +117,33 @@ void TestMaxima::testWarning()
 
     //the actual warning string "rat: replaced 7.5 by 15/2 = 7.5" which we don't checked since it's translated,
     //we just check it's existance.
-    QVERIFY(e->results().at(0)->data().toString().isEmpty() == false);
+    auto* result = dynamic_cast<Cantor::TextResult*>(e->results().at(0));
+    QVERIFY(e != nullptr);
+    QVERIFY(result->data().toString().isEmpty() == false);
+    QVERIFY(result->isWarning() == true);
 
     //the result of the calculation
     QCOMPARE(e->results().at(1)->data().toString(), QLatin1String("15/2"));
 }
 
+/*!
+ * test the output of the tex() function which is similarly formatted as other functions producing warning
+ * but which shouldn't be treated as a warning.
+ * */
+void TestMaxima::testWarning02()
+{
+    auto* e = evalExp( QLatin1String("tex(\"sin(x)\")") );
+
+    QVERIFY(e != nullptr);
+    QVERIFY(e->results().size() == 2); //two results, the TeX output and an additional 'false'
+
+    //the actual TeX string is of no interest for us, we just check it's existance.
+    auto* result = dynamic_cast<Cantor::TextResult*>(e->results().at(0));
+    QVERIFY(e != nullptr);
+    QVERIFY(result->data().toString().isEmpty() == false);
+    QVERIFY(result->isWarning() == false);
+}
+
 void TestMaxima::testExprNumbering()
 {
     Cantor::Expression* e=evalExp( QLatin1String("kill(labels)") ); //first reset the labels

src/backends/maxima/testmaxima.h

 /*
     SPDX-License-Identifier: GPL-2.0-or-later
     SPDX-FileCopyrightText: 2009 Alexander Rieder <alexanderrieder@gmail.com>
+    SPDX-FileCopyrightText: 2018-2022 by Alexander Semke (alexander.semke@web.de)
 */
 
 #ifndef _TESTMAXIMA_H
@@ -32,7 +33,8 @@ private Q_SLOTS:
 
     //tests a syntax error (not closing bracket)
     void testInvalidSyntax();
-    void testWarning();
+    void testWarning01();
+    void testWarning02();
     //tests if the expression numbering works
     void testExprNumbering();
     void testInvalidAssignment();

src/lib/textresult.cpp

 /*
     SPDX-License-Identifier: GPL-2.0-or-later
     SPDX-FileCopyrightText: 2009 Alexander Rieder <alexanderrieder@gmail.com>
+    SPDX-FileCopyrightText: 2022 Alexander Semke <alexander.semke@web.de>
 */
 
 #include "textresult.h"
@@ -26,15 +27,11 @@ QString rtrim(const QString& s)
 class Cantor::TextResultPrivate
 {
 public:
-    TextResultPrivate()
-    {
-        format=TextResult::PlainTextFormat;
-    }
-
     QString data;
     QString plain;
-    TextResult::Format format;
+    TextResult::Format format{TextResult::PlainTextFormat};
     bool isStderr{false};
+    bool isWarning{false};
 };
 
 TextResult::TextResult(const QString& data) : d(new TextResultPrivate)
@@ -49,12 +46,21 @@ TextResult::TextResult(const QString& data, const QString& plain) : d(new TextRe
     d->plain=rtrim(plain);
 }
 
-
 TextResult::~TextResult()
 {
     delete d;
 }
 
+void TextResult::setIsWarning(bool value)
+{
+    d->isWarning = value;
+}
+
+bool TextResult::isWarning() const
+{
+    return d->isWarning;
+}
+
 QString TextResult::toHtml()
 {
     QString s=d->data.toHtmlEscaped();

src/lib/textresult.h

 /*
     SPDX-License-Identifier: GPL-2.0-or-later
     SPDX-FileCopyrightText: 2009 Alexander Rieder <alexanderrieder@gmail.com>
+    SPDX-FileCopyrightText: 2022 Alexander Semke <alexander.semke@web.de>
 */
 
 #ifndef _TEXTRESULT_H
@@ -19,10 +20,14 @@ class CANTOR_EXPORT TextResult : public Result
   public:
     enum { Type=1 };
     enum Format { PlainTextFormat, LatexFormat};
+
     TextResult(const QString& text);
     TextResult(const QString& text, const QString& plain);
     ~TextResult() override;
 
+    void setIsWarning(bool);
+    bool isWarning() const;
+
     QString toHtml() override;
     QVariant data() override;
 

src/textresultitem.cpp

@@ -30,6 +30,10 @@ TextResultItem::TextResultItem(WorksheetEntry* parent, Cantor::Result* result)
     setTextInteractionFlags(Qt::TextSelectableByMouse);
     update();
 
+    auto* textResult = dynamic_cast<Cantor::TextResult*>(result);
+    if (textResult && textResult->isWarning())
+        setDefaultTextColor(qApp->palette().color(QPalette::Highlight));
+
     // So useful behaviour:
     // If we have HtmlResult, but after setting we have empty document
     // So show Plain version - it more useful