Build Clipper with `tools=no` and patch it to auto-disable exceptions

Reverts "Build polygon clipper only in tools builds" (see #17319)
which allows to build Clipper with tools disabled (release) and because
of that, Clipper has to be patched to optionally disable exceptions in
order to be built on some platforms.

Patched Clipper 6.4.2 to be compiled with exceptions enabled/disabled.
and ensure that Clipper-specific exception macros are defined: don't use
exceptions by default unless exception handling is detected.

Compilation with exceptions will be determined by various
C++ exceptions defines:

* ` __cpp_exceptions` is part of C++ feature testing macros (since C++98);
* `__EXCEPTIONS` is used by some GNU compilers;
* `_CPPUNWIND` is used by MSVC.

The user can override specific exceptions behavior via corresponding
`*_USER` macros (i.e. compiling for embedded systems).

2 files changed, 200 insertions, 14 deletions

diff --git a/thirdparty/misc/clipper-exceptions.patch b/thirdparty/misc/clipper-exceptions.patch
new file mode 100644
index 0000000000..537afd59b3
--- /dev/null
+++ b/thirdparty/misc/clipper-exceptions.patch
@@ -0,0 +1,154 @@
+diff --git a/thirdparty/misc/clipper.cpp b/thirdparty/misc/clipper.cpp
+index 8c3a59c4ca..c67045d113 100644
+--- a/thirdparty/misc/clipper.cpp
++++ b/thirdparty/misc/clipper.cpp
+@@ -48,6 +48,38 @@
+ #include <ostream>
+ #include <functional>
+ 
++//Explicitly disables exceptions handling for target platform
++//#define CLIPPER_NOEXCEPTION
++
++#define CLIPPER_THROW(exception) std::abort()
++#define CLIPPER_TRY if(true)
++#define CLIPPER_CATCH(exception) if(false)
++
++#if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)
++  #ifndef CLIPPER_NOEXCEPTION
++    #undef CLIPPER_THROW
++    #define CLIPPER_THROW(exception) throw exception
++    #undef CLIPPER_TRY
++    #define CLIPPER_TRY try
++    #undef CLIPPER_CATCH
++    #define CLIPPER_CATCH(exception) catch(exception)
++  #endif
++#endif
++
++//Optionally allows to override exception macros
++#if defined(CLIPPER_THROW_USER)
++	#undef CLIPPER_THROW
++	#define CLIPPER_THROW CLIPPER_THROW_USER
++#endif
++#if defined(CLIPPER_TRY_USER)
++	#undef CLIPPER_TRY
++	#define CLIPPER_TRY CLIPPER_TRY_USER
++#endif
++#if defined(CLIPPER_CATCH_USER)
++	#undef CLIPPER_CATCH
++	#define CLIPPER_CATCH CLIPPER_CATCH_USER
++#endif
++
+ namespace ClipperLib {
+ 
+ static double const pi = 3.141592653589793238;
+@@ -898,7 +930,7 @@ void RangeTest(const IntPoint& Pt, bool& useFullRange)
+   if (useFullRange)
+   {
+     if (Pt.X > hiRange || Pt.Y > hiRange || -Pt.X > hiRange || -Pt.Y > hiRange) 
+-      throw clipperException("Coordinate outside allowed range");
++      CLIPPER_THROW(clipperException("Coordinate outside allowed range"));
+   }
+   else if (Pt.X > loRange|| Pt.Y > loRange || -Pt.X > loRange || -Pt.Y > loRange) 
+   {
+@@ -1046,10 +1078,10 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
+ {
+ #ifdef use_lines
+   if (!Closed && PolyTyp == ptClip)
+-    throw clipperException("AddPath: Open paths must be subject.");
++    CLIPPER_THROW(clipperException("AddPath: Open paths must be subject."));
+ #else
+   if (!Closed)
+-    throw clipperException("AddPath: Open paths have been disabled.");
++    CLIPPER_THROW(clipperException("AddPath: Open paths have been disabled."));
+ #endif
+ 
+   int highI = (int)pg.size() -1;
+@@ -1062,7 +1094,7 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
+ 
+   bool IsFlat = true;
+   //1. Basic (first) edge initialization ...
+-  try
++  CLIPPER_TRY
+   {
+     edges[1].Curr = pg[1];
+     RangeTest(pg[0], m_UseFullRange);
+@@ -1075,10 +1107,10 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
+       InitEdge(&edges[i], &edges[i+1], &edges[i-1], pg[i]);
+     }
+   }
+-  catch(...)
++  CLIPPER_CATCH(...)
+   {
+     delete [] edges;
+-    throw; //range test fails
++    CLIPPER_THROW(); //range test fails
+   }
+   TEdge *eStart = &edges[0];
+ 
+@@ -1442,7 +1474,7 @@ void ClipperBase::SwapPositionsInAEL(TEdge *Edge1, TEdge *Edge2)
+ void ClipperBase::UpdateEdgeIntoAEL(TEdge *&e)
+ {
+   if (!e->NextInLML) 
+-    throw clipperException("UpdateEdgeIntoAEL: invalid call");
++    CLIPPER_THROW(clipperException("UpdateEdgeIntoAEL: invalid call"));
+ 
+   e->NextInLML->OutIdx = e->OutIdx;
+   TEdge* AelPrev = e->PrevInAEL;
+@@ -1510,7 +1542,7 @@ bool Clipper::Execute(ClipType clipType, Paths &solution,
+ {
+   if( m_ExecuteLocked ) return false;
+   if (m_HasOpenPaths)
+-    throw clipperException("Error: PolyTree struct is needed for open path clipping.");
++    CLIPPER_THROW(clipperException("Error: PolyTree struct is needed for open path clipping."));
+   m_ExecuteLocked = true;
+   solution.resize(0);
+   m_SubjFillType = subjFillType;
+@@ -1560,7 +1592,7 @@ void Clipper::FixHoleLinkage(OutRec &outrec)
+ bool Clipper::ExecuteInternal()
+ {
+   bool succeeded = true;
+-  try {
++  CLIPPER_TRY {
+     Reset();
+     m_Maxima = MaximaList();
+     m_SortedEdges = 0;
+@@ -1583,7 +1615,7 @@ bool Clipper::ExecuteInternal()
+       InsertLocalMinimaIntoAEL(botY);
+     }
+   }
+-  catch(...) 
++  CLIPPER_CATCH(...) 
+   {
+     succeeded = false;
+   }
+@@ -2827,18 +2859,18 @@ void Clipper::ProcessHorizontal(TEdge *horzEdge)
+ bool Clipper::ProcessIntersections(const cInt topY)
+ {
+   if( !m_ActiveEdges ) return true;
+-  try {
++  CLIPPER_TRY {
+     BuildIntersectList(topY);
+     size_t IlSize = m_IntersectList.size();
+     if (IlSize == 0) return true;
+     if (IlSize == 1 || FixupIntersectionOrder()) ProcessIntersectList();
+     else return false;
+   }
+-  catch(...) 
++  CLIPPER_CATCH(...) 
+   {
+     m_SortedEdges = 0;
+     DisposeIntersectNodes();
+-    throw clipperException("ProcessIntersections error");
++    CLIPPER_THROW(clipperException("ProcessIntersections error"));
+   }
+   m_SortedEdges = 0;
+   return true;
+@@ -3002,7 +3034,7 @@ void Clipper::DoMaxima(TEdge *e)
+     DeleteFromAEL(eMaxPair);
+   } 
+ #endif
+-  else throw clipperException("DoMaxima error");
++  else CLIPPER_THROW(clipperException("DoMaxima error"));
+ }
+ //------------------------------------------------------------------------------
+ 
diff --git a/thirdparty/misc/clipper.cpp b/thirdparty/misc/clipper.cpp
index 8c3a59c4ca..c67045d113 100644
--- a/thirdparty/misc/clipper.cpp
+++ b/thirdparty/misc/clipper.cpp
@@ -48,6 +48,38 @@
 #include <ostream>
 #include <functional>
 
+//Explicitly disables exceptions handling for target platform
+//#define CLIPPER_NOEXCEPTION
+
+#define CLIPPER_THROW(exception) std::abort()
+#define CLIPPER_TRY if(true)
+#define CLIPPER_CATCH(exception) if(false)
+
+#if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)
+  #ifndef CLIPPER_NOEXCEPTION
+    #undef CLIPPER_THROW
+    #define CLIPPER_THROW(exception) throw exception
+    #undef CLIPPER_TRY
+    #define CLIPPER_TRY try
+    #undef CLIPPER_CATCH
+    #define CLIPPER_CATCH(exception) catch(exception)
+  #endif
+#endif
+
+//Optionally allows to override exception macros
+#if defined(CLIPPER_THROW_USER)
+	#undef CLIPPER_THROW
+	#define CLIPPER_THROW CLIPPER_THROW_USER
+#endif
+#if defined(CLIPPER_TRY_USER)
+	#undef CLIPPER_TRY
+	#define CLIPPER_TRY CLIPPER_TRY_USER
+#endif
+#if defined(CLIPPER_CATCH_USER)
+	#undef CLIPPER_CATCH
+	#define CLIPPER_CATCH CLIPPER_CATCH_USER
+#endif
+
 namespace ClipperLib {
 
 static double const pi = 3.141592653589793238;
@@ -898,7 +930,7 @@ void RangeTest(const IntPoint& Pt, bool& useFullRange)
   if (useFullRange)
   {
     if (Pt.X > hiRange || Pt.Y > hiRange || -Pt.X > hiRange || -Pt.Y > hiRange) 
-      throw clipperException("Coordinate outside allowed range");
+      CLIPPER_THROW(clipperException("Coordinate outside allowed range"));
   }
   else if (Pt.X > loRange|| Pt.Y > loRange || -Pt.X > loRange || -Pt.Y > loRange) 
   {
@@ -1046,10 +1078,10 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
 {
 #ifdef use_lines
   if (!Closed && PolyTyp == ptClip)
-    throw clipperException("AddPath: Open paths must be subject.");
+    CLIPPER_THROW(clipperException("AddPath: Open paths must be subject."));
 #else
   if (!Closed)
-    throw clipperException("AddPath: Open paths have been disabled.");
+    CLIPPER_THROW(clipperException("AddPath: Open paths have been disabled."));
 #endif
 
   int highI = (int)pg.size() -1;
@@ -1062,7 +1094,7 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
 
   bool IsFlat = true;
   //1. Basic (first) edge initialization ...
-  try
+  CLIPPER_TRY
   {
     edges[1].Curr = pg[1];
     RangeTest(pg[0], m_UseFullRange);
@@ -1075,10 +1107,10 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
       InitEdge(&edges[i], &edges[i+1], &edges[i-1], pg[i]);
     }
   }
-  catch(...)
+  CLIPPER_CATCH(...)
   {
     delete [] edges;
-    throw; //range test fails
+    CLIPPER_THROW(); //range test fails
   }
   TEdge *eStart = &edges[0];
 
@@ -1442,7 +1474,7 @@ void ClipperBase::SwapPositionsInAEL(TEdge *Edge1, TEdge *Edge2)
 void ClipperBase::UpdateEdgeIntoAEL(TEdge *&e)
 {
   if (!e->NextInLML) 
-    throw clipperException("UpdateEdgeIntoAEL: invalid call");
+    CLIPPER_THROW(clipperException("UpdateEdgeIntoAEL: invalid call"));
 
   e->NextInLML->OutIdx = e->OutIdx;
   TEdge* AelPrev = e->PrevInAEL;
@@ -1510,7 +1542,7 @@ bool Clipper::Execute(ClipType clipType, Paths &solution,
 {
   if( m_ExecuteLocked ) return false;
   if (m_HasOpenPaths)
-    throw clipperException("Error: PolyTree struct is needed for open path clipping.");
+    CLIPPER_THROW(clipperException("Error: PolyTree struct is needed for open path clipping."));
   m_ExecuteLocked = true;
   solution.resize(0);
   m_SubjFillType = subjFillType;
@@ -1560,7 +1592,7 @@ void Clipper::FixHoleLinkage(OutRec &outrec)
 bool Clipper::ExecuteInternal()
 {
   bool succeeded = true;
-  try {
+  CLIPPER_TRY {
     Reset();
     m_Maxima = MaximaList();
     m_SortedEdges = 0;
@@ -1583,7 +1615,7 @@ bool Clipper::ExecuteInternal()
       InsertLocalMinimaIntoAEL(botY);
     }
   }
-  catch(...) 
+  CLIPPER_CATCH(...) 
   {
     succeeded = false;
   }
@@ -2827,18 +2859,18 @@ void Clipper::ProcessHorizontal(TEdge *horzEdge)
 bool Clipper::ProcessIntersections(const cInt topY)
 {
   if( !m_ActiveEdges ) return true;
-  try {
+  CLIPPER_TRY {
     BuildIntersectList(topY);
     size_t IlSize = m_IntersectList.size();
     if (IlSize == 0) return true;
     if (IlSize == 1 || FixupIntersectionOrder()) ProcessIntersectList();
     else return false;
   }
-  catch(...) 
+  CLIPPER_CATCH(...) 
   {
     m_SortedEdges = 0;
     DisposeIntersectNodes();
-    throw clipperException("ProcessIntersections error");
+    CLIPPER_THROW(clipperException("ProcessIntersections error"));
   }
   m_SortedEdges = 0;
   return true;
@@ -3002,7 +3034,7 @@ void Clipper::DoMaxima(TEdge *e)
     DeleteFromAEL(eMaxPair);
   } 
 #endif
-  else throw clipperException("DoMaxima error");
+  else CLIPPER_THROW(clipperException("DoMaxima error"));
 }
 //------------------------------------------------------------------------------