[LLVMbugs] [Bug 22492] New: Range-for rejects constexpr on loop variable

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=22492

            Bug ID: 22492
           Summary: Range-for rejects constexpr on loop variable
           Product: clang
           Version: trunk
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: C++11
          Assignee: unassignedclangbugs at nondot.org
          Reporter: hstong at ca.ibm.com
                CC: dgregor at apple.com, llvmbugs at cs.uiuc.edu
    Classification: Unclassified

According to N3290 subclause 6.5.4 [stmt.ranged]/2, constexpr is explicitly
allowed in the decl-specifier-seq of a for-range-declaration.

For the source below, Clang produces an error; GCC compiles it fine.

### SOURCE (<stdin>):
struct Range {
   struct It { operator int &(); int val; };
   It begin();
   It end();
} range;

constexpr int operator*(const Range::It &) { return 0; }

int main() {
   for (constexpr int x : range) { }
}


### COMPILER INVOCATION:
clang -cc1 -std=c++11 -x c++ -


### ACTUAL OUTPUT:
<stdin>:10:9: error: loop variable 'x' may not be declared 'constexpr'
   for (constexpr int x : range) { }
        ^
1 error generated.


### EXPECTED OUTPUT:
Clean compile.


### COMPILER VERSION INFO:
clang version 3.7.0 (trunk 228401)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation:
/usr/local/gcc-4.8.2/lib/gcc/x86_64-unknown-linux-gnu/4.8.2
Selected GCC installation:
/usr/local/gcc-4.8.2/lib/gcc/x86_64-unknown-linux-gnu/4.8.2
Candidate multilib: .;@m64
Selected multilib: .;@m64

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