[flang][driver] Add checks for missing option arguments

With this patch, the following invocation of the frontend driver will
return an error:
```
flang-new -fc1 input-file.f90 -o
```
Similar logic applies to other options that require arguments.

Similar checks are already available in the compiler driver, flang-new
(that's implemented in clangDriver).

Differential Revision: https://reviews.llvm.org/D103554

1 files changed, 7 insertions, 0 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 1d18dda..6d9a3a7 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -501,6 +501,13 @@ bool CompilerInvocation::CreateFromArgs(CompilerInvocation &res,
   llvm::opt::InputArgList args = opts.ParseArgs(
       commandLineArgs, missingArgIndex, missingArgCount, includedFlagsBitmask);
 
+  // Check for missing argument error.
+  if (missingArgCount) {
+    diags.Report(clang::diag::err_drv_missing_argument)
+        << args.getArgString(missingArgIndex) << missingArgCount;
+    success = false;
+  }
+
   // Issue errors on unknown arguments
   for (const auto *a : args.filtered(clang::driver::options::OPT_UNKNOWN)) {
     auto argString = a->getAsString(args);