<div dir="ltr">Might be a good candidate for Clang 6.0.1.</div><div class="gmail_extra"><br><div class="gmail_quote">On 8 March 2018 at 18:00, Richard Smith via cfe-commits <span dir="ltr"><<a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: rsmith<br>
Date: Thu Mar  8 18:00:01 2018<br>
New Revision: 327099<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=327099&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project?rev=327099&view=rev</a><br>
Log:<br>
PR36645: Go looking for an appropriate array bound when constant-evaluating a<br>
name of an array object.<br>
<br>
Modified:<br>
    cfe/trunk/lib/AST/<wbr>ExprConstant.cpp<br>
    cfe/trunk/test/SemaCXX/<wbr>constant-expression-cxx11.cpp<br>
<br>
Modified: cfe/trunk/lib/AST/<wbr>ExprConstant.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=327099&r1=327098&r2=327099&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/cfe/trunk/lib/AST/<wbr>ExprConstant.cpp?rev=327099&<wbr>r1=327098&r2=327099&view=diff</a><br>
==============================<wbr>==============================<wbr>==================<br>
--- cfe/trunk/lib/AST/<wbr>ExprConstant.cpp (original)<br>
+++ cfe/trunk/lib/AST/<wbr>ExprConstant.cpp Thu Mar  8 18:00:01 2018<br>
@@ -63,14 +63,22 @@ namespace {<br>
<br>
   static QualType getType(APValue::LValueBase B) {<br>
     if (!B) return QualType();<br>
-    if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>())<br>
+    if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {<br>
       // FIXME: It's unclear where we're supposed to take the type from, and<br>
-      // this actually matters for arrays of unknown bound. Using the type of<br>
-      // the most recent declaration isn't clearly correct in general. Eg:<br>
+      // this actually matters for arrays of unknown bound. Eg:<br>
       //<br>
       // extern int arr[]; void f() { extern int arr[3]; };<br>
       // constexpr int *p = &arr[1]; // valid?<br>
-      return cast<ValueDecl>(D-><wbr>getMostRecentDecl())->getType(<wbr>);<br>
+      //<br>
+      // For now, we take the array bound from the most recent declaration.<br>
+      for (auto *Redecl = cast<ValueDecl>(D-><wbr>getMostRecentDecl()); Redecl;<br>
+           Redecl = cast_or_null<ValueDecl>(<wbr>Redecl->getPreviousDecl())) {<br>
+        QualType T = Redecl->getType();<br>
+        if (!T->isIncompleteArrayType())<br>
+          return T;<br>
+      }<br>
+      return D->getType();<br>
+    }<br>
<br>
     const Expr *Base = B.get<const Expr*>();<br>
<br>
<br>
Modified: cfe/trunk/test/SemaCXX/<wbr>constant-expression-cxx11.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp?rev=327099&r1=327098&r2=327099&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/cfe/trunk/test/<wbr>SemaCXX/constant-expression-<wbr>cxx11.cpp?rev=327099&r1=<wbr>327098&r2=327099&view=diff</a><br>
==============================<wbr>==============================<wbr>==================<br>
--- cfe/trunk/test/SemaCXX/<wbr>constant-expression-cxx11.cpp (original)<br>
+++ cfe/trunk/test/SemaCXX/<wbr>constant-expression-cxx11.cpp Thu Mar  8 18:00:01 2018<br>
@@ -629,6 +629,10 @@ namespace ArrayOfUnknownBound {<br>
<br>
   extern const int carr[]; // expected-note {{here}}<br>
   constexpr int n = carr[0]; // expected-error {{constant}} expected-note {{non-constexpr variable}}<br>
+<br>
+  constexpr int local_extern[] = {1, 2, 3};<br>
+  void f() { extern const int local_extern[]; }<br>
+  static_assert(local_extern[1] == 2, "");<br>
 }<br>
<br>
 namespace DependentValues {<br>
<br>
<br>
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</blockquote></div><br></div>