[clang] [flang] [flang] Align `-x` language modes with `gfortran` (PR #130268)

[Tarun Prabhu via cfe-commits]

=?utf-8?q?Iñaki?= Amatria Barral <inaki.amatria at appentra.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/130268 at github.com>


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@@ -0,0 +1,35 @@
+program main
+  print *, __FILE__, __LINE__
+end
+
+! This test verifies that `flang`'s `-x` options behave like `gfortran`'s.
+! Specifically:
+! - `-x f95` should process the file based on its extension unless overridden.
+! - `-x f95-cpp-input` should behave like `-x f95` but with preprocessing
+!   (`-cpp`) enabled unless overridden.
+
+! ---
+! Ensure the file is treated as fixed-form unless explicitly set otherwise
+! ---
+! RUN: not %flang -Werror -x f95 -cpp %s 2>&1 | FileCheck --check-prefix=SCAN-ERROR %s
+! RUN: not %flang -Werror -x f95-cpp-input %s 2>&1 | FileCheck --check-prefix=SCAN-ERROR %s
+
+! SCAN-ERROR: error
+
+! RUN: %flang -Werror -x f95 -cpp -ffree-form %s 2>&1 | FileCheck --check-prefix=NO-SCAN-ERROR --allow-empty %s
+! RUN: %flang -Werror -x f95-cpp-input -ffree-form %s 2>&1 | FileCheck --check-prefix=NO-SCAN-ERROR --allow-empty %s
+
+! NO-SCAN-ERROR-NOT: error
+
+! ---
+! Ensure `-cpp` is not enabled by default unless explicitly requested
+! ---
+! RUN: not %flang -Werror -x f95 -ffree-form %s 2>&1 | FileCheck --check-prefix=SEMA-ERROR %s
+! RUN: not %flang -Werror -x f95-cpp-input -nocpp -ffree-form %s 2>&1 | FileCheck --check-prefix=SEMA-ERROR %s
+
+! SEMA-ERROR: error
----------------
tarunprabhu wrote:

It's always a balancing act. 

In this case, you are checking that the compiler parses the file in a specific way. In that case, you expect to see a specific category of error, so you might as well check for that. That way, if a change elsewhere in the compiler results in a different error, the test failure will alert the developer. It may be that this "new" error is expected. Or, it could indicate that the change had an effect on a seemingly unrelated part of the code. In either case, it forces the developer to take a closer look. 

That's just my opinion, though. 

https://github.com/llvm/llvm-project/pull/130268