[clang][Interp] Handle one-past-the-end pointers in SubPtr

ChuanqiXu9 · Jun 6, 2024 · 026fbdf · 026fbdf
1 parent 86295dc
commit 026fbdf
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Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/clang/lib/AST/Interp/Interp.h b/clang/lib/AST/Interp/Interp.h
@@ -1773,8 +1773,10 @@ inline bool SubPtr(InterpState &S, CodePtr OpPC) {
     return true;
   }
 
-  T A = T::from(LHS.getIndex());
-  T B = T::from(RHS.getIndex());
+  T A = LHS.isElementPastEnd() ? T::from(LHS.getNumElems())
+                               : T::from(LHS.getIndex());
+  T B = RHS.isElementPastEnd() ? T::from(RHS.getNumElems())
+                               : T::from(RHS.getIndex());
   return AddSubMulHelper<T, T::sub, std::minus>(S, OpPC, A.bitWidth(), A, B);
 }
 

diff --git a/clang/test/AST/Interp/arrays.cpp b/clang/test/AST/Interp/arrays.cpp
@@ -609,3 +609,9 @@ namespace ArrayMemberAccess {
     bool cond = a->x;
   }
 }
+
+namespace OnePastEndSub {
+  struct A {};
+  constexpr A a[3][3];
+  constexpr int diff2 = &a[1][3] - &a[1][0]; /// Used to crash.
+}