[LLVMbugs] [Bug 9993] New: Enum with explicit enum-base is not promoted to int

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Mon May 23 12:49:14 PDT 2011


http://llvm.org/bugs/show_bug.cgi?id=9993

           Summary: Enum with explicit enum-base is not promoted to int
           Product: clang
           Version: trunk
          Platform: Macintosh
        OS/Version: MacOS X
            Status: NEW
          Severity: normal
          Priority: P
         Component: C++0x
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: jonathan.sauer at gmx.de
                CC: llvmbugs at cs.uiuc.edu, dgregor at apple.com


The following program fails to compile with clang r131897:

//enum e: unsigned int {      // (A)
enum e: unsigned short {  // (B)
    A,
    B,
    C
};

int main(int, char**)
{
    e    a = A;
    return a > 0;
}


The error message is: "use of overloaded operator '>' is ambiguous (with
operand types 'e' and 'int')"


As integral promotions can promote "a" to both "unsigned short" (the enum-base)
and "int" (the promoted enum-base), the latter being the type of the "0" that
"a" is being compared with, this code should compile (and return false/0).

When line (A) is replaced by line (B), the code compiles.


On cfe-dev, Johannes Schaub posted another program that fails to compile as
well (<http://lists.cs.uiuc.edu/pipermail/cfe-dev/2011-May/015220.html>):

enum e : unsigned short { };
void f(int); // should take this
void f(long);

int main() {
 e e1;
 f(e1);
}


In this case, the error message is: "call to 'f' is ambiguous".

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