[flang][preprocessor] Don't expand INCLUDE under -E by default (#110333)

Fortran INCLUDE lines have (until now) been treated like #include
directives. This isn't how things work with other Fortran compilers when
running under the -E option for preprocessing only, so stop doing it by
default, and add -fpreprocess-include-lines to turn it back on when
desired.

2 files changed, 10 insertions, 0 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index d68534d..2154b9a 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -820,6 +820,8 @@ static void parsePreprocessorArgs(Fortran::frontend::PreprocessorOptions &opts,
             : PPMacrosFlag::Exclude;
 
   opts.noReformat = args.hasArg(clang::driver::options::OPT_fno_reformat);
+  opts.preprocessIncludeLines =
+      args.hasArg(clang::driver::options::OPT_fpreprocess_include_lines);
   opts.noLineDirectives = args.hasArg(clang::driver::options::OPT_P);
   opts.showMacros = args.hasArg(clang::driver::options::OPT_dM);
 }
@@ -1486,6 +1488,10 @@ void CompilerInvocation::setFortranOpts() {
   }
   fortranOptions.fixedFormColumns = frontendOptions.fixedFormColumns;
 
+  // -E
+  fortranOptions.prescanAndReformat =
+      frontendOptions.programAction == PrintPreprocessedInput;
+
   fortranOptions.features = frontendOptions.features;
   fortranOptions.encoding = frontendOptions.encoding;
 
diff --git a/flang/lib/Frontend/FrontendAction.cpp b/flang/lib/Frontend/FrontendAction.cpp
index 42a614f..041182b 100644
--- a/flang/lib/Frontend/FrontendAction.cpp
+++ b/flang/lib/Frontend/FrontendAction.cpp
@@ -95,6 +95,10 @@ bool FrontendAction::beginSourceFile(CompilerInstance &ci,
         getCurrentInput().getIsCUDAFortran());
   }
 
+  // -fpreprocess-include-lines
+  invoc.getFortranOpts().expandIncludeLinesInPreprocessedOutput =
+      invoc.getPreprocessorOpts().preprocessIncludeLines;
+
   // Decide between fixed and free form (if the user didn't express any
   // preference, use the file extension to decide)
   if (invoc.getFrontendOpts().fortranForm == FortranForm::Unknown) {