[flang][Driver] Add support of -fd-lines-as-comments and -fd-lines-as-code flags (#127605)

`-fd-lines-as-code` and `-fd-lines-as-comments` enables treatment for
lines beginning with `d` or `D` in fixed form sources.
Using these options in free form has no effect.
If the `-fd-lines-as-code` option is given they are treated as if the
first column contained a blank.
If the `-fd-lines-as-comments` option is given, they are treated as
comment lines.

1 files changed, 26 insertions, 0 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 724316f..8b07a50 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -961,6 +961,32 @@ static bool parseDialectArgs(CompilerInvocation &res, llvm::opt::ArgList &args,
                              clang::DiagnosticsEngine &diags) {
   unsigned numErrorsBefore = diags.getNumErrors();
 
+  // -fd-lines-as-code
+  if (args.hasArg(clang::driver::options::OPT_fd_lines_as_code)) {
+    if (res.getFrontendOpts().fortranForm == FortranForm::FreeForm) {
+      const unsigned fdLinesAsWarning = diags.getCustomDiagID(
+          clang::DiagnosticsEngine::Warning,
+          "‘-fd-lines-as-code’ has no effect in free form.");
+      diags.Report(fdLinesAsWarning);
+    } else {
+      res.getFrontendOpts().features.Enable(
+          Fortran::common::LanguageFeature::OldDebugLines, true);
+    }
+  }
+
+  // -fd-lines-as-comments
+  if (args.hasArg(clang::driver::options::OPT_fd_lines_as_comments)) {
+    if (res.getFrontendOpts().fortranForm == FortranForm::FreeForm) {
+      const unsigned fdLinesAsWarning = diags.getCustomDiagID(
+          clang::DiagnosticsEngine::Warning,
+          "‘-fd-lines-as-comments’ has no effect in free form.");
+      diags.Report(fdLinesAsWarning);
+    } else {
+      res.getFrontendOpts().features.Enable(
+          Fortran::common::LanguageFeature::OldDebugLines, false);
+    }
+  }
+
   // -fdefault* family
   if (args.hasArg(clang::driver::options::OPT_fdefault_real_8)) {
     res.getDefaultKinds().set_defaultRealKind(8);