[PATCH] D154301: Fix aggregate CTAD with string literals adding extra const

[Mital Ashok via Phabricator via cfe-commits]

MitalAshok created this revision.
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MitalAshok retitled this revision from "Fix CTAD with string literals adding extra const" to "Fix aggregate CTAD with string literals adding extra const".
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================
Comment at: clang/lib/Sema/SemaInit.cpp:10707
         //   if e_i is of array type and x_i is a bstring-literal, T_i is an
         //   lvalue reference to the const-qualified declared type of e_i and
         // C++ [over.match.class.deduct]p1.10:
----------------
The "const-qualified" here was missing


Missing a `withConst`, so when deducing from a string literal, a `const` is erroneously added to the deduced type.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D154301

Files:
  clang/lib/Sema/SemaInit.cpp
  clang/test/CXX/over/over.match/over.match.funcs/over.match.class.deduct/p1-9.cpp


Index: clang/test/CXX/over/over.match/over.match.funcs/over.match.class.deduct/p1-9.cpp
===================================================================
--- /dev/null
+++ clang/test/CXX/over/over.match/over.match.funcs/over.match.class.deduct/p1-9.cpp
@@ -0,0 +1,55 @@
+// RUN: %clang_cc1 -verify -std=c++20 %s
+
+using size_t = decltype(sizeof(int));
+
+template<class T, size_t N>
+struct H {
+  T array[N];
+};
+template<class T, size_t N>
+struct I {
+  volatile T array[N];
+};
+template<size_t N>
+struct J {  // expected-note 3{{candidate}}
+  unsigned char array[N];
+};
+
+H h = { "abc" };
+I i = { "def" };
+static_assert(__is_same(decltype(h), H<char, 4>));  // Not H<const char, 4>
+static_assert(__is_same(decltype(i), I<char, 4>));
+
+J j = { "ghi" };  // expected-error {{no viable constructor or deduction guide}}
+
+template<size_t N>
+struct K {
+  char array[N];
+};
+K k = { "abc" };
+static_assert(__is_same(decltype(k), K<4>));
+
+template<typename T, size_t N>
+struct L {
+  const T array[N];
+};
+L l = { "abc" };
+static_assert(__is_same(decltype(l), L<char, 4>));
+
+template<typename T>
+struct M {
+  T array[sizeof(T) == 0 ? 4 : 4];
+};
+M m = { "abc" };
+static_assert(__is_same(decltype(m), M<char>));
+
+/*
+template<typename T>
+struct N {
+  T array[4];
+};
+// The C99 extension, brace elision for designated initializers,
+// makes `T = const char*` viable, and that is used instead
+N n = { .array = "abc" };
+static_assert(__is_same(decltype(n), N<char>));
+ */
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -10714,7 +10714,8 @@
               ElementTypes[I] = Context.getRValueReferenceType(ElementTypes[I]);
             else if (isa<StringLiteral>(
                          ListInit->getInit(I)->IgnoreParenImpCasts()))
-              ElementTypes[I] = Context.getLValueReferenceType(ElementTypes[I]);
+              ElementTypes[I] =
+                  Context.getLValueReferenceType(ElementTypes[I].withConst());
           }
 
         llvm::FoldingSetNodeID ID;


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