issue doxygen#11939 LaTeX output does not properly break lines with long doxylink

There following parts are fixed:
- 5. Index
  Introducing the LaTeX environment `doxyIndexDescription` and setting an extra flag `escapeUnderscore` for the function `latexEscapeIndexChars` to false.
- 4. Section title
  Using the `escapeUnderscore` flag to determine wheter or not the "word breaking" doxygen LaTeX command `\+` can be used (was by default set to `true` in the `filterLatexString`, when always usingh `false` would lead to TeX capacity exceeded or to `\+` in the index output).
- 1. File Index
  Solved due to point 4.

Author: albert-github

src/latexgen.cpp

@@ -2563,7 +2563,7 @@ QCString latexEscapeLabelName(const QCString &s)
   return t.str();
 }
 
-QCString latexEscapeIndexChars(const QCString &s)
+QCString latexEscapeIndexChars(const QCString &s, bool escapeUnderscore)
 {
   //printf("latexEscapeIndexChars(%s)\n",qPrint(s));
   if (s.isEmpty()) return s;
@@ -2583,6 +2583,7 @@ QCString latexEscapeIndexChars(const QCString &s)
       case ']': t << "]"; break;
       case '{': t << "\\lcurly{}"; break;
       case '}': t << "\\rcurly{}"; break;
+      case '_': if (!escapeUnderscore) {t << "_"; break;}
       // NOTE: adding a case here, means adding it to while below as well!
       default:
         {
@@ -2591,12 +2592,13 @@ QCString latexEscapeIndexChars(const QCString &s)
           tmp[i++]=c;
           while ((c=*p) && c!='"' && c!='@' && c!='[' && c!=']' && c!='!' && c!='{' && c!='}' && c!='|')
           {
+            if (c=='_' && !escapeUnderscore) break;
             tmp[i++]=c;
             p++;
           }
           tmp[i]=0;
           filterLatexString(t,tmp,
-                            true,   // insideTabbing
+                            !escapeUnderscore,   // "insideTabbing"
                             false,  // insidePre
                             false,  // insideItem
                             false,  // insideTable
@@ -2674,16 +2676,16 @@ void latexWriteIndexItem(TextStream &m_t,const QCString &s1,const QCString &s2)
   {
     m_t << "\\index{";
     m_t << latexEscapeLabelName(s1);
-    m_t << "@{";
-    m_t << latexEscapeIndexChars(s1);
-    m_t << "}";
+    m_t << "@{\\doxyIndexDescription{";
+    m_t << latexEscapeIndexChars(s1,false);
+    m_t << "}}";
     if (!s2.isEmpty())
     {
       m_t << "!";
       m_t << latexEscapeLabelName(s2);
-      m_t << "@{";
-      m_t << latexEscapeIndexChars(s2);
-      m_t << "}";
+      m_t << "@{\\doxyIndexDescription{";
+      m_t << latexEscapeIndexChars(s2,false);
+      m_t << "}}";
     }
     m_t << "}\n";
   }

src/latexgen.h

@@ -344,7 +344,7 @@ void filterLatexString(TextStream &t,const QCString &str,
                        const bool retainNewline = false);
 
 QCString latexEscapeLabelName(const QCString &s);
-QCString latexEscapeIndexChars(const QCString &s);
+QCString latexEscapeIndexChars(const QCString &s, bool escapeUnderscore = true);
 QCString latexEscapePDFString(const QCString &s);
 QCString latexFilterURL(const QCString &s);
 void latexWriteIndexItem(TextStream &t,const QCString &r1,const QCString &s2 = "");

templates/latex/header.tex

@@ -42,6 +42,11 @@
   \newenvironment{NoHyper}{}{}
 %%END !PDF_HYPERLINKS
 
+  \usepackage{xurl}
+  \newcommand{\doxyIndexDescription}[1]{%
+    \begin{NoHyper}\url{#1}\end{NoHyper}%
+  }
+
   \usepackage{doxygen}
 
   $extralatexstylesheet