Add enableDebugSol following discussion on mailing list

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 ### Added
+- Added enableDebugSol() and disableDebugSol() for controlling the debug solution mechanism if DEBUGSOL=true
 - More support for AND-Constraints
 - Added support for knapsack constraints
 - Added isPositive(), isNegative(), isFeasLE(), isFeasLT(), isFeasGE(), isFeasGT(), isHugeValue(), and tests

docs/build.rst

@@ -159,8 +159,10 @@ Build with Debug
 To use debug information in PySCIPOpt you need to build it with the following command:
 
 .. code-block::
-
-  python -m pip install --install-option="--debug" .
+
+  export CFLAGS="-UNDEBUG"
+  export CXXFLAGS="-UNDEBUG"
+  python -m pip install .
 
 .. note:: Be aware that you will need the debug library of the SCIP Optimization Suite for this to work
   (cmake .. -DCMAKE_BUILD_TYPE=Debug).

src/pyscipopt/scip.pxd

@@ -924,6 +924,8 @@ cdef extern from "scip/scip.h":
     SCIP_Real SCIPgetSolTime(SCIP* scip, SCIP_SOL* sol)
 
     SCIP_RETCODE SCIPsetRelaxSolVal(SCIP* scip, SCIP_RELAX* relax, SCIP_VAR* var, SCIP_Real val)
+    void SCIPenableDebugSol(SCIP* scip)
+    void SCIPdisableDebugSol(SCIP* scip)
 
     # Row Methods
     SCIP_RETCODE SCIPcreateRow(SCIP* scip, SCIP_ROW** row, const char* name, int len, SCIP_COL** cols, SCIP_Real* vals,

src/pyscipopt/scip.pxi

@@ -56,6 +56,14 @@
 _SCIP_BOUNDTYPE_TO_STRING = {SCIP_BOUNDTYPE_UPPER: '<=',
                              SCIP_BOUNDTYPE_LOWER: '>='}
 
+cdef extern from "scip/config.h":
+    """
+    #ifndef WITH_DEBUG_SOLUTION
+    #define WITH_DEBUG_SOLUTION 0
+    #endif
+    """
+    bint WITH_DEBUG_SOLUTION
+
 # Mapping the SCIP_RESULT enum to a python class
 # This is required to return SCIP_RESULT in the python code
 # In __init__.py this is imported as SCIP_RESULT to keep the
@@ -141,7 +149,6 @@
     INFORUNBD      = SCIP_STATUS_INFORUNBD
 
 StageNames = {}
-
 cdef class PY_SCIP_STAGE:
     INIT         = SCIP_STAGE_INIT
     PROBLEM      = SCIP_STAGE_PROBLEM
@@ -171,7 +178,6 @@
     SUBROOT     = SCIP_NODETYPE_SUBROOT
     REFOCUSNODE = SCIP_NODETYPE_REFOCUSNODE
 
-
 cdef class PY_SCIP_PROPTIMING:
     BEFORELP     = SCIP_PROPTIMING_BEFORELP
     DURINGLPLOOP = SCIP_PROPTIMING_DURINGLPLOOP
@@ -198,7 +204,6 @@
     AFTERPROPLOOP     = SCIP_HEURTIMING_AFTERPROPLOOP
 
 EventNames = {}
-
 cdef class PY_SCIP_EVENTTYPE:
     DISABLED        = SCIP_EVENTTYPE_DISABLED
     VARADDED        = SCIP_EVENTTYPE_VARADDED
@@ -301,7 +306,7 @@
     if rc == SCIP_OKAY:
         pass
     elif rc == SCIP_ERROR:
         raise Exception('SCIP: unspecified error!')
     elif rc == SCIP_NOMEMORY:
         raise MemoryError('SCIP: insufficient memory error!')
     elif rc == SCIP_READERROR:
@@ -7495,6 +7500,24 @@
         """
         PY_SCIP_CALL(SCIPsetRelaxSolVal(self._scip, NULL, var.scip_var, val))
 
+    def enableDebugSol(self):
+        """
+        Enables the debug solution mechanism, which allows tracing back the invalidation of
+        a debug solution during the solution process of SCIP. It must be explicitly
+        enabled for the SCIP data structure.
+        """
+        if not WITH_DEBUG_SOLUTION:
+            raise RuntimeError("SCIP must be built with `DEBUGSOL=true` to enable the debug solution mechanism.")
+        SCIPenableDebugSol(self._scip)
+
+    def disableDebugSol(self):
+        """
+        Disables the debug solution mechanism.
+        """
+        if not WITH_DEBUG_SOLUTION:
+            raise RuntimeError("SCIP must be built with `DEBUGSOL=true` to disable the debug solution mechanism.")
+        SCIPdisableDebugSol(self._scip)
+
     def getConss(self, transformed=True):
         """
         Retrieve all constraints.