[flang][driver] Add `-fno-analyzed-objects-for-unparse`

This patch adds a new option for the new Flang driver:
`-fno-analyzed-objects-for-unparse`. The semantics are similar to
`-funparse-typed-exprs-to-f18-fc` from `f18`. For consistency, the
latter is replaced with `-fno-analyzed-objects-for-unparse`.

The new option controls the behaviour of the unparser (i.e. the action
corresponding to `-fdebug-unparse`). The default behaviour is to use the
analyzed objects when unparsing. The new flag can be used to turn this
off, so that the original parse-tree objects are used. The analyzed
objects are generated during the semantic checks [1].

This patch also updates the semantics of
`-fno-analyzed-objects-for-unparse`/`-funparse-typed-exprs-to-f18-fc`
in `f18`, so that this flag is always taken into account when `Unparse`
is used (this way the semantics in `f18` and `flang-new` are identical).

The added test file is based on example from Peter Steinfeld.

[1]
https://github.com/llvm/llvm-project/blob/main/flang/docs/Semantics.md

Differential Revision: https://reviews.llvm.org/D103612

1 files changed, 6 insertions, 0 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index dc771ec..6a2bf19 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -404,6 +404,12 @@ static bool parseSemaArgs(CompilerInvocation &res, llvm::opt::ArgList &args,
     res.SetModuleFileSuffix(moduleSuffix->getValue());
   }
 
+  // -fno-analyzed-objects-for-unparse
+  if (args.hasArg(
+          clang::driver::options::OPT_fno_analyzed_objects_for_unparse)) {
+    res.SetUseAnalyzedObjectsForUnparse(false);
+  }
+
   return diags.getNumErrors() == numErrorsBefore;
 }