[flang][driver] NFC: Make code more in line with LLVM style

This patch basically implements [1] in ExecuteCompilerInvocation.cpp. It
also:
  * replaces `CreateFrontendBaseAction` with `CreateFrontendAction`
    (only one method is needed ATM, this change removes the extra
    indirection)
  * removes `InvalidAction` from the `ActionKind` enum (I don't think it
    adds much and keeping it would mean adding a new void case in
    `CreateFrontendAction`)
  * sets the default frontend action in FrontendOptions.h to
    `ParseSyntaxOnly` (note that this is still overridden independently
    in `ParseFrontendArg` in CompilerInvocation.cpp)

No new functionality is added, hence no tests.

[1] https://llvm.org/docs/CodingStandards.html#don-t-use-default-labels-in-fully-covered-switches-over-enumerations

Differential Revision: https://reviews.llvm.org/D124245

1 files changed, 0 insertions, 3 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 0f0db57..d56566d 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -98,9 +98,6 @@ static void ParseTargetArgs(TargetOptions &opts, llvm::opt::ArgList &args) {
 
 // Tweak the frontend configuration based on the frontend action
 static void setUpFrontendBasedOnAction(FrontendOptions &opts) {
-  assert(opts.programAction != Fortran::frontend::InvalidAction &&
-      "Fortran frontend action not set!");
-
   if (opts.programAction == DebugDumpParsingLog)
     opts.instrumentedParse = true;