failed cell dependency check should not set invalid values (tdf#132451)

Calc's dependency check done before parallel formula cell group
calculation tries to ensure valid cell values for all the dependencies
of the group's cell, and if it detects a problem such as a cycle
it bails out. But since ScFormulaCell::Interpret() simply bailed out
without doing anything, other cells could use that cell's possibly
incorrect value for their calculation and get their dirty flag reset.

This fix adds a flag to mark that bailing out is in progress, which
ensures the bail-out is short-circuited and no cell values are set.

Change-Id: Ia93c70d456682e19ce533abd2cf65ce35ffed9ca
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/96838
Reviewed-by: Dennis Francis <dennis.francis@collabora.com>
Tested-by: Jenkins

1 files changed, 8 insertions, 2 deletions

diff --git a/sc/inc/recursionhelper.hxx b/sc/inc/recursionhelper.hxx
index 10c4ddc6f02e..48508ec61e64 100644
--- a/sc/inc/recursionhelper.hxx
+++ b/sc/inc/recursionhelper.hxx
@@ -63,6 +63,7 @@ class ScRecursionHelper
     bool                                bInIterationReturn;
     bool                                bConverging;
     bool                                bGroupsIndependent;
+    bool                                bAbortingDependencyComputation;
     std::vector< ScFormulaCell* >       aTemporaryGroupCells;
     o3tl::sorted_vector< ScFormulaCellGroup* >* pFGSet;
 
@@ -76,8 +77,8 @@ public:
     void    IncRecursionCount()             { ++nRecursionCount; }
     void    DecRecursionCount()             { --nRecursionCount; }
     sal_uInt16 GetDepComputeLevel() const   { return nDependencyComputationLevel; }
-    void    IncDepComputeLevel()            { ++nDependencyComputationLevel; }
-    void    DecDepComputeLevel()            { --nDependencyComputationLevel; }
+    void    IncDepComputeLevel();
+    void    DecDepComputeLevel();
     /// A pure recursion return, no iteration.
     bool    IsInRecursionReturn() const     { return bInRecursionReturn &&
         !bInIterationReturn; }
@@ -115,6 +116,11 @@ public:
     bool AnyCycleMemberInDependencyEvalMode(ScFormulaCell* pCell);
     bool AnyParentFGInCycle();
     void SetFormulaGroupDepEvalMode(bool bSet);
+    // When dependency computation detects a cycle, it may not compute proper cell values.
+    // This sets a flag that ScFormulaCell will use to avoid setting those new values
+    // and resetting the dirty flag, until the dependency computation bails out.
+    void AbortDependencyComputation();
+    bool IsAbortingDependencyComputation() const { return bAbortingDependencyComputation; }
 
     void AddTemporaryGroupCell(ScFormulaCell* cell);
     void CleanTemporaryGroupCells();