[clang] Consider array filler in MaybeElementDependentArrayfiller()

Any InitListExpr may have an array filler and since we may be evaluating
the array filler as well, we need to take into account that the array
filler expression might make the InitListExpr element dependent.

Fixes https://github.com/llvm/llvm-project/issues/56016

Differential Revision: https://reviews.llvm.org/D131155

3 files changed, 33 insertions, 0 deletions

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c9f65b271413..a2d7526bb770 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -62,6 +62,10 @@ Bug Fixes
   already properly diagnosing this case).
 - Fix clang not properly diagnosing the failing subexpression when chained
   binary operators are used in a ``static_assert`` expression.
+- Fix a crash when evaluating a multi-dimensional array's array filler
+  expression is element-dependent. This fixes
+  `Issue 50601 <https://github.com/llvm/llvm-project/issues/56016>`_.
+
 
 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 6f3539a4b2c1..36f957711316 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -10695,6 +10695,11 @@ static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) {
       if (MaybeElementDependentArrayFiller(ILE->getInit(I)))
         return true;
     }
+
+    if (ILE->hasArrayFiller() &&
+        MaybeElementDependentArrayFiller(ILE->getArrayFiller()))
+      return true;
+
     return false;
   }
   return true;
diff --git a/clang/test/SemaCXX/constexpr-array-init.cpp b/clang/test/SemaCXX/constexpr-array-init.cpp
new file mode 100644
index 000000000000..cb11f47fb3cb
--- /dev/null
+++ b/clang/test/SemaCXX/constexpr-array-init.cpp
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -std=c++20 -verify %s
+
+/// This test case used to crash in constant evaluation
+/// because of the two-dimensional array with an array
+/// filler expression.
+
+/// expected-no-diagnostics
+struct Foo {
+  int a;
+  constexpr Foo()
+      : a(get_int()) {
+  }
+
+  constexpr int get_int() const {
+    return 5;
+  }
+};
+
+static constexpr Foo bar[2][1] = {
+    {{}},
+};
+static_assert(bar[0][0].a == 5);
+static_assert(bar[1][0].a == 5);
+