[PATCH] D157554: [NFC][Clang] Fix static analyzer concern about null pointer dereference

[Elizabeth Andrews via Phabricator via cfe-commits]

eandrews created this revision.
eandrews added reviewers: tahonermann, aaron.ballman.
Herald added subscribers: manas, ASDenysPetrov, dkrupp, donat.nagy, Szelethus, a.sidorin, baloghadamsoftware.
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eandrews requested review of this revision.
Herald added a subscriber: wangpc.

Param->getTypeConstraint() can return nullptr, and was dereferenced without a check.

I followed the logic for invalid constraints and set Status as concepts::ExprRequirement::SS_ExprSubstitutionFailure if getTypeConstraint() returns null unexpectedly. I am not a 100% certain about this change since I am unfamiliar with concepts.


https://reviews.llvm.org/D157554

Files:
  clang/lib/Sema/SemaExprCXX.cpp


Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -9072,15 +9072,20 @@
     MultiLevelTemplateArgumentList MLTAL(Param, TAL.asArray(),
                                          /*Final=*/false);
     MLTAL.addOuterRetainedLevels(TPL->getDepth());
-    Expr *IDC = Param->getTypeConstraint()->getImmediatelyDeclaredConstraint();
-    ExprResult Constraint = SubstExpr(IDC, MLTAL);
-    if (Constraint.isInvalid()) {
+    const TypeConstraint *TC = Param->getTypeConstraint();
+    if (!TC) {
       Status = concepts::ExprRequirement::SS_ExprSubstitutionFailure;
     } else {
-      SubstitutedConstraintExpr =
-          cast<ConceptSpecializationExpr>(Constraint.get());
-      if (!SubstitutedConstraintExpr->isSatisfied())
-        Status = concepts::ExprRequirement::SS_ConstraintsNotSatisfied;
+      ExprResult Constraint =
+          SubstExpr(TC->getImmediatelyDeclaredConstraint(), MLTAL);
+      if (Constraint.isInvalid()) {
+        Status = concepts::ExprRequirement::SS_ExprSubstitutionFailure;
+      } else {
+        SubstitutedConstraintExpr =
+            cast<ConceptSpecializationExpr>(Constraint.get());
+        if (!SubstitutedConstraintExpr->isSatisfied())
+          Status = concepts::ExprRequirement::SS_ConstraintsNotSatisfied;
+      }
     }
   }
   return new (Context) concepts::ExprRequirement(E, IsSimple, NoexceptLoc,


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