IRGen: fix construction of ArrayRef

The type deduction may fail due to no explicit conversion to the
ArrayRef data type.  Add explicit casts.  Use the sizeof operator on the
value being constructed rather than the explicit type of the value to
allow the size to be deduced from the value.

Author: compnerd

lib/IRGen/IRGen.cpp

@@ -377,7 +377,8 @@ bool swift::performLLVM(IRGenOptions &Opts, DiagnosticEngine *Diags,
       if (DiagMutex) DiagMutex->unlock();
     );
 
-    ArrayRef<uint8_t> HashData(Result, sizeof(MD5::MD5Result));
+    ArrayRef<uint8_t> HashData(reinterpret_cast<uint8_t *>(&Result),
+                               sizeof(Result));
     if (Opts.OutputKind == IRGenOutputKind::ObjectFile &&
         !Opts.PrintInlineTree &&
         !needsRecompile(OutputFilename, HashData, HashGlobal, DiagMutex)) {

lib/IRGen/IRGenModule.cpp

@@ -1058,8 +1058,8 @@ bool IRGenModule::finalize() {
     // We have to create the variable now (before we emit the global lists).
     // But we want to calculate the hash later because later we can do it
     // multi-threaded.
-    llvm::MD5::MD5Result zero = { 0 };
-    ArrayRef<uint8_t> ZeroArr(zero, sizeof(llvm::MD5::MD5Result));
+    llvm::MD5::MD5Result zero{};
+    ArrayRef<uint8_t> ZeroArr(reinterpret_cast<uint8_t *>(&zero), sizeof(zero));
     auto *ZeroConst = llvm::ConstantDataArray::get(Module.getContext(), ZeroArr);
     ModuleHash = new llvm::GlobalVariable(Module, ZeroConst->getType(), true,
                                           llvm::GlobalValue::PrivateLinkage,