Fix buffer overflow

[michaelplatings]

Summary

In practice this wasn't a problem because the overflow was into another
buffer that was immediately overwritten, but the compiler warning was
annoying.

[michaelplatings]

@lhames ping

[lhames]

Sorry I missed this earlier. Someone else spotted the same issue -- it should be fixed by 4db6c717c4dc768dba2dd4fd25ace1ad9029a32a. I think this can be closed.

llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp

auto AddSection = [&](SecDesc &SD, jitlink::Section &GraphSec) {
     SD.Sec.flags = MachO::S_REGULAR;
   };
 
   // Add the __objc_imageinfo section.
   {
     DataSections.push_back({});
     auto &SD = DataSections.back();
     memset(&SD.Sec, 0, sizeof(SD.Sec));
-    strcpy(SD.Sec.sectname, "__objc_imageinfo");
+    // The terminating nul byte doesn't fit into the sectname array so use
+    // memcpy instead of strcpy. (Using strncpy causes a compiler warning).
+    const char SectName[] = "__objc_imageinfo";
+    static_assert(sizeof(SD.Sec.sectname) == sizeof(SectName) - 1);
+    memcpy(SD.Sec.sectname, SectName, sizeof(SD.Sec.sectname));
     strcpy(SD.Sec.segname, "__DATA");
     SD.Sec.size = 8;
     SD.AddFixups = [&](size_t RecordOffset) {
       jitlink::Edge::Kind PointerEdge = jitlink::Edge::Invalid;
       switch (G.getTargetTriple().getArch()) {
       case Triple::aarch64:
         PointerEdge = jitlink::aarch64::Pointer64;
         break;