Remove -fdebug-parsing-log from this patch as it requires additional work that can be implemented in a separate patch.
Also address review comments by @awarzynski

Rebase off main

In D96716#2569594, @awarzynski wrote:

We need %f18 to be replaced with %flang_fc1, but we don't need -fsyntax-only, right?

In D96716#2569102, @awarzynski wrote:

This patch doesn't require the tests to be updated, does it?

Make semantics_ private

Rebase off main

Rebase off main

Thanks for clarifying

Thanks for working on this @awarzynski
Do you know what the use of GetActionKindName in FrontendOptions.h is, as it is currently not being called anywhere and whilst this patch currently does not update that method with the 2 new cases, even if it did no change would be visible.
Other than that, looks good to me!

Address review comment

This patch makes sense to me as the behaviour of the new driver is similar to clang in that only the last action-related option is run, e.g:

• Only -emit-llvm is run in: clang -cc1 -ast-dump -emit-llvm file.c
• Only -ast-dump is run in: clang -cc1 -emit-llvm -ast-dump file.c

This change will mean -fsyntax-only does not need to be specified when running -fdebug-dump-parse-tree or -fdebug-dump-symbols as it will always be run when either one of these action-related options are present.
LGTM!

Address review comment

Rebase off main

Thanks for working on this @awarzynski!
I've left a comment on the test but otherwise looks good to me.

Thanks for working on this @awarzynski, this patch allows actions that do not need to run the prescanner to not do so.
I've left a nit, but otherwise LRTM!

Address review comment

Remove -fno-fixed-form and -fno-free-form

Address review comment

Add f18 RUN line

Rename flang-driver to flang

Thanks for working on this @awarzynski

I've built the latest main branch with -DBUILD_SHARED_LIBS=On and it failed. Applying this patch has resolved that.
Looks good to me.

Remove target-specific predefinition

Add helper methods to Utils

Add include-module test

Update regression test

In D94228#2492906, @awarzynski wrote:

I think that it would be useful to add a test like this:
Input name: `input.f:

program ShouldFail
end

Run line:

flang-new -E input.f

This should fail as flang-new will identify the input it as fixed-form, yet the actual file is free form.

Add a new test

Support more extensions

Rename test files

Address minor changes in review comments

Clean up test

Address review comments

Address review comments