[clang] c8c9af1 - [clang][Interp] Decay arrays to the first element (#72660)

[via cfe-commits]

Author: Timm Baeder
Date: 2023-12-12T11:01:47+01:00
New Revision: c8c9af150d34306ee0af94baf8357891ace233ba

URL: https://github.com/llvm/llvm-project/commit/c8c9af150d34306ee0af94baf8357891ace233ba
DIFF: https://github.com/llvm/llvm-project/commit/c8c9af150d34306ee0af94baf8357891ace233ba.diff

LOG: [clang][Interp] Decay arrays to the first element (#72660)

This way we have a pointer to the
first element on the stack.

Added: 
    

Modified: 
    clang/lib/AST/Interp/Interp.h
    clang/test/AST/Interp/arrays.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/Interp/Interp.h b/clang/lib/AST/Interp/Interp.h
index 6cf122f2ba55e1..a240d74d63425e 100644
--- a/clang/lib/AST/Interp/Interp.h
+++ b/clang/lib/AST/Interp/Interp.h
@@ -1826,10 +1826,12 @@ inline bool ArrayElemPtr(InterpState &S, CodePtr OpPC) {
 /// Just takes a pointer and checks if its' an incomplete
 /// array type.
 inline bool ArrayDecay(InterpState &S, CodePtr OpPC) {
-  const Pointer &Ptr = S.Stk.peek<Pointer>();
+  const Pointer &Ptr = S.Stk.pop<Pointer>();
 
-  if (!Ptr.isUnknownSizeArray())
+  if (!Ptr.isUnknownSizeArray()) {
+    S.Stk.push<Pointer>(Ptr.atIndex(0));
     return true;
+  }
 
   const SourceInfo &E = S.Current->getSource(OpPC);
   S.FFDiag(E, diag::note_constexpr_unsupported_unsized_array);

diff  --git a/clang/test/AST/Interp/arrays.cpp b/clang/test/AST/Interp/arrays.cpp
index 34e0086fb9ee8c..c455731e76699f 100644
--- a/clang/test/AST/Interp/arrays.cpp
+++ b/clang/test/AST/Interp/arrays.cpp
@@ -27,6 +27,10 @@ static_assert(foo[2][3] == &m, "");
 static_assert(foo[2][4] == nullptr, "");
 
 
+constexpr int SomeInt[] = {1};
+constexpr int getSomeInt() { return *SomeInt; }
+static_assert(getSomeInt() == 1, "");
+
 /// A init list for a primitive value.
 constexpr int f{5};
 static_assert(f == 5, "");