[PATCH] D152003: [clang] Fix `static_cast` to array of unknown bound

[Mariya Podchishchaeva via Phabricator via cfe-commits]

Fznamznon updated this revision to Diff 538165.
Fznamznon added a comment.

Rebase, move the logic, modify c-style casts as well


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D152003/new/

https://reviews.llvm.org/D152003

Files:
  clang/docs/ReleaseNotes.rst
  clang/lib/Sema/SemaType.cpp
  clang/test/SemaCXX/paren-list-agg-init.cpp


Index: clang/test/SemaCXX/paren-list-agg-init.cpp
===================================================================
--- clang/test/SemaCXX/paren-list-agg-init.cpp
+++ clang/test/SemaCXX/paren-list-agg-init.cpp
@@ -273,7 +273,6 @@
 // beforecxx20-warning at -2 {{aggregate initialization of type 'A' from a parenthesized list of values is a C++20 extension}}
 }
 
-
 namespace GH63278 {
 struct S {
   int a = 0;
@@ -294,3 +293,23 @@
 }
 
 }
+
+namespace gh62863 {
+int (&&arr)[] = static_cast<int[]>(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arr1)[1] = static_cast<int[]>(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arr2)[2] = static_cast<int[]>(42); // expected-error {{reference to type 'int[2]' could not bind to an rvalue of type 'int[1]'}}
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arr3)[3] = static_cast<int[3]>(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[3]' from a parenthesized list of values is a C++20 extension}}
+
+int (&&arr4)[] = (int[])(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arr5)[1] = (int[])(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arr6)[2] = (int[])(42); // expected-error {{reference to type 'int[2]' could not bind to an rvalue of type 'int[1]'}}
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arr7)[3] = (int[3])(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[3]' from a parenthesized list of values is a C++20 extension}}
+}
Index: clang/lib/Sema/SemaType.cpp
===================================================================
--- clang/lib/Sema/SemaType.cpp
+++ clang/lib/Sema/SemaType.cpp
@@ -8853,6 +8853,18 @@
       }
     }
   }
+  if (isa<ExplicitCastExpr>(E)) {
+    QualType DestType = E->getType();
+    if (const auto *IAT = Context.getAsIncompleteArrayType(DestType)) {
+      // C++20 [expr.static.cast]p.4: ... If T is “array of unknown bound of U”,
+      // this direct-initialization defines the type of the expression as U[1]
+      QualType ResultType = Context.getConstantArrayType(
+          IAT->getElementType(),
+          llvm::APInt(Context.getTypeSize(Context.getSizeType()), 1),
+          /*SizeExpr=*/nullptr, ArrayType::Normal, /*IndexTypeQuals=*/0);
+      E->setType(ResultType);
+    }
+  }
 }
 
 QualType Sema::getCompletedType(Expr *E) {
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -573,6 +573,8 @@
 - Stop evaluating a constant expression if the condition expression which in
   switch statement contains errors.
   (`#63453 <https://github.com/llvm/llvm-project/issues/63453>_`)
+- Fixed `static_cast` to array of unknown bound.
+  (`#62863 <https://github.com/llvm/llvm-project/issues/62863>`_).
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


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