[clang] [flang] [flang][driver] Add options -fdefault-integer-4 and -fdefault-real-4 (PR #172323)

[Eugene Epshteyn via cfe-commits]

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@@ -1086,15 +1086,35 @@ static bool parseDialectArgs(CompilerInvocation &res, llvm::opt::ArgList &args,
   }
 
   // -fdefault* family
-  if (args.hasArg(clang::options::OPT_fdefault_real_8)) {
-    res.getDefaultKinds().set_defaultRealKind(8);
-    res.getDefaultKinds().set_doublePrecisionKind(16);
+  if (const llvm::opt::Arg *arg =
+          args.getLastArg(clang::options::OPT_fdefault_real_8,
+                          clang::options::OPT_fdefault_real_4)) {
+    const llvm::opt::Option &opt = arg->getOption();
+    if (opt.matches(clang::options::OPT_fdefault_real_8)) {
+      res.getDefaultKinds().set_defaultRealKind(8);
+      res.getDefaultKinds().set_doublePrecisionKind(16);
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eugeneepshteyn wrote:

Hmm, what if the target platform doesn't support real16?

https://github.com/llvm/llvm-project/pull/172323