Fix nm on GCC 5.1 after the C++14 move

[jfb]

Summary

As in D66306, fix the invocation of std::sort with std::function by not using
std::function, since it's easier to read and is broken in libstdc++ from GCC 5.1
(see https://gcc.gnu.org/PR65942).

[thakis]

Thanks again!

llvm/tools/llvm-nm/llvm-nm.cpp

717 ↗

(On Diff #215460)

Nit: I find the staggered if on the lhs easier to readh than the nested ternary

[jfb]

• Use if instead of ternary

[rupprecht]

Sounds like you get to claim this as a fix for https://bugs.llvm.org/show_bug.cgi?id=24115 too :)

[jfb]

In D66310#1632135, @rupprecht wrote:

Sounds like you get to claim this as a fix for https://bugs.llvm.org/show_bug.cgi?id=24115 too :)

Sounds about right, thanks for pointing this out. I've closed the bug.

llvm/trunk/tools/llvm-nm/llvm-nm.cpp

 static bool symbolIsDefined(const NMSymbol &Sym) {
   return Sym.TypeChar != 'U' && Sym.TypeChar != 'w' && Sym.TypeChar != 'v';
 }
 
 static void sortAndPrintSymbolList(SymbolicFile &Obj, bool printName,
                                    const std::string &ArchiveName,
                                    const std::string &ArchitectureName) {
   if (!NoSort) {
-    std::function<bool(const NMSymbol &, const NMSymbol &)> Cmp;
+    using Comparator = bool (*)(const NMSymbol &, const NMSymbol &);
+    Comparator Cmp;
     if (NumericSort)
-      Cmp = compareSymbolAddress;
+      Cmp = &compareSymbolAddress;
     else if (SizeSort)
-      Cmp = compareSymbolSize;
+      Cmp = &compareSymbolSize;
     else
-      Cmp = compareSymbolName;
+      Cmp = &compareSymbolName;
 
     if (ReverseSort)
-      Cmp = [=](const NMSymbol &A, const NMSymbol &B) { return Cmp(B, A); };
+      llvm::sort(SymbolList, [=](const NMSymbol &A, const NMSymbol &B) -> bool {
+        return Cmp(B, A);
+      });
+    else
       llvm::sort(SymbolList, Cmp);
   }
 
   if (!PrintFileName) {
     if (OutputFormat == posix && MultipleFiles && printName) {
       outs() << '\n' << CurrentFilename << ":\n";
     } else if (OutputFormat == bsd && MultipleFiles && printName) {
       outs() << "\n" << CurrentFilename << ":\n";
     } else if (OutputFormat == sysv) {