This patch adds support for the `-cpp` and `-nocpp` flags. The
implemented semantics match f18 (i.e. the "throwaway" driver), but are
different to gfortran. In Flang the preprocessor is always run. Instead,
`-cpp/-nocpp` are used to control whether predefined and command-line
preprocessor macro definitions are enabled or not. In practice this is
sufficient to model gfortran`s `-cpp/-nocpp`.
In the absence of `-cpp/-nocpp`, the driver will use the extension of
the input file to decide whether to include the standard macro
predefinitions. gfortran's documentation [1] was used to decide which
file extension to use for this.
The logic mentioned above was added in FrontendAction::BeginSourceFile.
That's relatively late in the driver set-up, but this roughly where the
name of the input file becomes available. The logic for deciding between
fixed and free form works in a similar way and was also moved to
FrontendAction::BeginSourceFile for consistency (and to reduce
code-duplication).
The `-cpp/-nocpp` flags are respected also when the input is read from
stdin. This is different to:
* gfortran (behaves as if `-cpp` was used)
* f18 (behaves as if `-nocpp` was used)
Starting with this patch, file extensions are significant and some test
files had to be renamed to reflect that. Where possible, preprocessor
tests were updated so that they can be shared between `f18` and
`flang-new`. This was implemented on top of adding new test for
`-cpp/-nocpp`.
[1] https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html
Reviewed By: kiranchandramohan
Differential Revision: https://reviews.llvm.org/D99292
Until now we've been maintaining 2 test directories for Flang's drivers:
* test/Driver for `f18` (the current driver)
* test/Flang-Driver for `flang-new` (the new driver)
As we have started sharing tests between the drivers, this separation is
no longer required. This patch merges the two test directories. As
suggested in the review, moving forward we'll avoid having tests
specifically for the old driver.
A few notable changes:
* Driver/version-test.f90 and Driver/no-files.f90 are deleted. The
versions for the new driver are more robust, but tricky to share.
* Driver/write-module.f90 is deleted in favour of
Flang-Driver/write-module.f90 (see https://reviews.llvm.org/D97197
for more context)
Differential Revision: https://reviews.llvm.org/D98257
Andrzej Warzynski