Merge branch '3924-fix-scip-exact-mode-segfaults-double-free-on-exit-2' into 'master'

Resolve "SCIP exact mode segfaults (double free?) on exit" status

See merge request integer/scip!3853

Author: DominikKamp

src/scip/lpexact.c

@@ -2135,6 +2135,7 @@ SCIP_RETCODE lpExactFlushAddRows(
    lp->solved = FALSE;
    lp->primalfeasible = FALSE;
    lp->primalchecked = FALSE;
+   lp->lpsolstat = SCIP_LPSOLSTAT_NOTSOLVED;
 
    return SCIP_OKAY;
 }
@@ -2247,6 +2248,7 @@ SCIP_RETCODE lpExactFlushChgCols(
       lp->solved = FALSE;
       lp->dualfeasible = FALSE;
       lp->dualchecked = FALSE;
+      lp->lpsolstat = SCIP_LPSOLSTAT_NOTSOLVED;
    }
 
    /* change bounds in LP */
@@ -2259,6 +2261,7 @@ SCIP_RETCODE lpExactFlushChgCols(
       lp->solved = FALSE;
       lp->primalfeasible = FALSE;
       lp->primalchecked = FALSE;
+      lp->lpsolstat = SCIP_LPSOLSTAT_NOTSOLVED;
    }
 
    lp->nchgcols = 0;
@@ -2366,6 +2369,7 @@ SCIP_RETCODE lpExactFlushChgRows(
       lp->solved = FALSE;
       lp->primalfeasible = FALSE;
       lp->primalchecked = FALSE;
+      lp->lpsolstat = SCIP_LPSOLSTAT_NOTSOLVED;
    }
 
    lp->nchgrows = 0;
@@ -3678,6 +3682,7 @@ SCIP_RETCODE SCIPlpExactFlush(
    /* we can't retrieve the solution from Qsoptex after anything was changed, so we need to resolve the lp */
 #ifdef SCIP_WITH_QSOPTEX
    lp->solved = FALSE;
+   lp->lpsolstat = SCIP_LPSOLSTAT_NOTSOLVED;
 #endif
 
    assert(lp->nlpicols == lp->ncols);
@@ -7893,12 +7898,14 @@ SCIP_RETCODE lpExactRestoreSolVals(
    storedsolvals = lpexact->storedsolvals;
    if( storedsolvals != NULL )
    {
-      lpexact->solved = storedsolvals->lpissolved;
 #ifdef SCIP_WITH_QSOPTEX
       lpexact->solved = FALSE;
+      lpexact->lpsolstat = SCIP_LPSOLSTAT_NOTSOLVED;
+#else
+      lpexact->solved = storedsolvals->lpissolved;
+      lpexact->lpsolstat = storedsolvals->lpsolstat;
 #endif
       SCIPrationalSetRational(lpexact->lpobjval, storedsolvals->lpobjval);
-      lpexact->lpsolstat = storedsolvals->lpsolstat;
       lpexact->primalfeasible = storedsolvals->primalfeasible;
       lpexact->primalchecked = storedsolvals->primalchecked;
       lpexact->dualfeasible = storedsolvals->dualfeasible;

src/scip/lpexact_bounding.c

@@ -1206,12 +1206,18 @@ SCIP_RETCODE projectShift(
    int shift;
    SCIP_Bool isfeas;
 
+   assert(lp != NULL);
+   assert(lp->solved);
+   assert(lpexact != NULL);
+   assert(set != NULL);
+   assert(safebound != NULL);
+
    /* project-and-shift method:
     * 1. projection step (to ensure that equalities are satisfied):
     *   - compute error in equalities: r=c-Ay^
     *   - backsolve system of equations to find correction of error: z with Dz=r
     *   - add corretion to approximate dual solution: bold(y)=y^+[z 0]
-    * 2. shifing step (to ensure that inequalities are satisfied):
+    * 2. shifting step (to ensure that inequalities are satisfied):
     *   - take convex combination of projected approximate point bold(y) with interior point y*
     * 3. compute dual objective value of feasible dual solution and set bound
     */
@@ -1269,8 +1275,7 @@ SCIP_RETCODE projectShift(
    SCIP_CALL( SCIPrationalCreateBuffer(set->buffer, &maxv) );
    SCIP_CALL( SCIPrationalCreateBuffer(set->buffer, &dualbound) );
 
-   /* flush exact lp */
-   /* set up the exact lpi for the current node */
+   /* set up the exact lpi for the current node and flush exact lp */
    SCIP_CALL( SCIPlpExactSyncLPs(lpexact, blkmem, set) );
    SCIP_CALL( SCIPlpExactFlush(lp->lpexact, blkmem, set, eventqueue) );
 
@@ -2010,15 +2015,12 @@ SCIP_RETCODE boundShift(
    int i;
    int j;
 
-   assert(lpexact != NULL);
    assert(lp != NULL);
-   assert(lp->solved || lpexact->lpsolstat == SCIP_LPSOLSTAT_NOTSOLVED);
+   assert(lp->solved);
+   assert(lpexact != NULL);
    assert(set != NULL);
    assert(safebound != NULL);
 
-   lpexact->lpsolstat = SCIP_LPSOLSTAT_NOTSOLVED;
-   lpexact->solved = 0;
-
    if( !SCIPlpExactBoundShiftUseful(lpexact) )
       return SCIP_OKAY;