Fix aggregate CTAD with string literals adding extra const

Missing a `withConst`, so when deducing from a string literal, a `const` is erroneously added to the deduced type. Reviewed By: ychen Differential Revision: https://reviews.llvm.org/D154301
llvm · Jul 5, 2023 · 92f4bf2 · 92f4bf2
1 parent 2265bb0
commit 92f4bf2
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Showing 4 changed files with 39 additions and 14 deletions.
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
@@ -10714,7 +10714,8 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
               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;

diff --git a/clang/test/CXX/drs/dr26xx.cpp b/clang/test/CXX/drs/dr26xx.cpp
@@ -126,3 +126,27 @@ void f() {
     brachiosaur |= neck;                // OK
 }
 }
+
+namespace dr2681 { // dr2681: 17
+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}}
+}
diff --git a/clang/test/SemaTemplate/aggregate-deduction-candidate.cpp b/clang/test/SemaTemplate/aggregate-deduction-candidate.cpp
@@ -198,22 +198,22 @@ namespace Array {
   // CHECK: FunctionTemplateDecl {{.*}} implicit <deduction guide for A>
   // CHECK: |-TemplateTypeParmDecl {{.*}} referenced typename depth 0 index 0 T
   // CHECK: |-NonTypeTemplateParmDecl {{.*}} 'size_t':'unsigned {{.*}}' depth 0 index 1 N
-  // CHECK: |-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for A> 'auto (T (&)[N]) -> A<T, N>'
-  // CHECK: | `-ParmVarDecl {{.*}} 'T (&)[N]'
-  // CHECK: `-CXXDeductionGuideDecl {{.*}} implicit used <deduction guide for A> 'auto (const char (&)[5]) -> Array::A<const char, 5>'
-  // CHECK:   |-TemplateArgument type 'const char'
-  // CHECK:   | `-QualType {{.*}} 'const char' const
-  // CHECK:   |   `-BuiltinType {{.*}} 'char'
+  // CHECK: |-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for A> 'auto (const T (&)[N]) -> A<T, N>'
+  // CHECK: | `-ParmVarDecl {{.*}} 'const T (&)[N]'
+  // CHECK: `-CXXDeductionGuideDecl {{.*}} implicit used <deduction guide for A> 'auto (const char (&)[5]) -> Array::A<char, 5>'
+  // CHECK:   |-TemplateArgument type 'char'
+  // CHECK:   | `-BuiltinType {{.*}} 'char'
   // CHECK:   |-TemplateArgument integral 5
   // CHECK:   `-ParmVarDecl {{.*}} 'const char (&)[5]'
-  // CHECK: FunctionProtoType {{.*}} 'auto (T (&)[N]) -> A<T, N>' dependent trailing_return cdecl
+  // CHECK: FunctionProtoType {{.*}} 'auto (const T (&)[N]) -> A<T, N>' dependent trailing_return cdecl
   // CHECK: |-InjectedClassNameType {{.*}} 'A<T, N>' dependent
   // CHECK: | `-CXXRecord {{.*}} 'A'
-  // CHECK: `-LValueReferenceType {{.*}} 'T (&)[N]' dependent
-  // CHECK:   `-DependentSizedArrayType {{.*}} 'T[N]' dependent
-  // CHECK:     |-TemplateTypeParmType {{.*}} 'T' dependent depth 0 index 0
-  // CHECK:     | `-TemplateTypeParm {{.*}} 'T'
-  // CHECK:     `-DeclRefExpr {{.*}} 'size_t':'unsigned {{.*}}' NonTypeTemplateParm {{.*}} 'N' 'size_t':'unsigned {{.*}}'
+  // CHECK: `-LValueReferenceType {{.*}} 'const T (&)[N]' dependent
+  // CHECK:   `-QualType {{.*}} 'const T[N]' const
+  // CHECK:     `-DependentSizedArrayType {{.*}} 'T[N]' dependent
+  // CHECK:       |-TemplateTypeParmType {{.*}} 'T' dependent depth 0 index 0
+  // CHECK:       | `-TemplateTypeParm {{.*}} 'T'
+  // CHECK:       `-DeclRefExpr {{.*}} 'size_t':'unsigned{{.*}}' NonTypeTemplateParm {{.*}} 'N' 'size_t':'unsigned{{.*}}'
 }
 
 namespace BraceElision {

diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
@@ -15893,7 +15893,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/2681.html">2681</a></td>
     <td>DR</td>
     <td>Deducing member array type from string literal</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="unreleased" align="center">Clang 17</td>
   </tr>
   <tr id="2682">
     <td><a href="https://cplusplus.github.io/CWG/issues/2682.html">2682</a></td>