[llvm-bugs] [Bug 25627] New: constexpr value in a lambda

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=25627

            Bug ID: 25627
           Summary: constexpr value in a lambda
           Product: clang
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: C++14
          Assignee: unassignedclangbugs at nondot.org
          Reporter: al-iyaz at xs4all.nl
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 15348
  --> https://llvm.org/bugs/attachment.cgi?id=15348&action=edit
as explained

If I am correct the following code should be valid c++14:

template<int j> void g() {}
int main()
{
  constexpr int i = 0;
  auto f = []{ g<i>(); };
  return 0;
}

However, clang does not compile this code.
It does compile with when capturing [=], [i] or [&].
It also compiles if the i is made static.

This is related to a stackoverflow-question:
http://stackoverflow.com/questions/33873788/how-can-i-use-a-constexpr-value-in-a-lambda

clang version:
Debian clang version 3.8.0-svn247818-1~exp1 (trunk) (based on LLVM 3.8.0)
compile command:
clang++-3.8 -std=c++14 capture_constexpr.cpp

compiler error:
capture_constexpr.cpp:11:7: error: variable 'i' cannot be implicitly captured
in a lambda with no capture-default specified
    g<i>();
      ^
capture_constexpr.cpp:7:17: note: 'i' declared here
  constexpr int i = 0;
                ^
capture_constexpr.cpp:10:12: note: lambda expression begins here
  auto f = []{ // compiles with gcc 4.9.1, not with clang 3.8
           ^
1 error generated.

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