Add enableDebugSol following discussion on mailing list (#1013)

* Add enableDebugSol

* Add disableDebugSol and check

* update docs

* Apply suggestions from code review

Co-authored-by: DominikKamp <130753997+DominikKamp@users.noreply.github.com>

* remove redundant variable

* Fixed error during compilation, changed flag to PYSCIPOPT_WITH_DEBUG_SOLUTION to avoid side effect (#1040)

---------

Co-authored-by: DominikKamp <130753997+DominikKamp@users.noreply.github.com>
Co-authored-by: Gennesaret Kharistio Tjusila <33521666+gtjusila@users.noreply.github.com>

Author: 3 people

CHANGELOG.md

@@ -2,7 +2,6 @@
 
 ## Unreleased
 ### Added
-- Added recipe for getting local constraints
 - More support for AND-Constraints
 - Added support for knapsack constraints
 - Added isPositive(), isNegative(), isFeasLE(), isFeasLT(), isFeasGE(), isFeasGT(), isHugeValue(), and tests
@@ -12,6 +11,8 @@
 - Wrapped SCIPgetNLPBranchCands
 - Added getConsVals() to get coefficients of any linear type constraint
 - Generalized getLhs() and getRhs() to additionally support any linear type constraint
+- Added recipe for getting local constraints
+- Added enableDebugSol() and disableDebugSol() for controlling the debug solution mechanism if DEBUGSOL=true
 ### Fixed
 - Raised an error when an expression is used when a variable is required
 - Fixed some compile warnings

docs/build.rst

@@ -168,8 +168,10 @@ 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

@@ -917,6 +917,8 @@ 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 +56,16 @@ else:
 _SCIP_BOUNDTYPE_TO_STRING = {SCIP_BOUNDTYPE_UPPER: '<=',
                              SCIP_BOUNDTYPE_LOWER: '>='}
 
+cdef extern from "scip/config.h":
+    """
+    #ifdef WITH_DEBUG_SOLUTION
+    #define PYSCIPOPT_WITH_DEBUG_SOLUTION 1
+    #else
+    #define PYSCIPOPT_WITH_DEBUG_SOLUTION 0
+    #endif
+    """
+    bint PYSCIPOPT_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 +151,6 @@ cdef class PY_SCIP_STATUS:
     INFORUNBD      = SCIP_STATUS_INFORUNBD
 
 StageNames = {}
-
 cdef class PY_SCIP_STAGE:
     INIT         = SCIP_STAGE_INIT
     PROBLEM      = SCIP_STAGE_PROBLEM
@@ -171,7 +180,6 @@ cdef class PY_SCIP_NODETYPE:
     SUBROOT     = SCIP_NODETYPE_SUBROOT
     REFOCUSNODE = SCIP_NODETYPE_REFOCUSNODE
 
-
 cdef class PY_SCIP_PROPTIMING:
     BEFORELP     = SCIP_PROPTIMING_BEFORELP
     DURINGLPLOOP = SCIP_PROPTIMING_DURINGLPLOOP
@@ -198,7 +206,6 @@ cdef class PY_SCIP_HEURTIMING:
     AFTERPROPLOOP     = SCIP_HEURTIMING_AFTERPROPLOOP
 
 EventNames = {}
-
 cdef class PY_SCIP_EVENTTYPE:
     DISABLED        = SCIP_EVENTTYPE_DISABLED
     VARADDED        = SCIP_EVENTTYPE_VARADDED
@@ -7756,6 +7763,24 @@ cdef class Model:
         """
         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 PYSCIPOPT_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 PYSCIPOPT_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.