From 263377a175709c2d11f3ff63c2d2d2843afb91ea Mon Sep 17 00:00:00 2001 From: Tarun Prabhu Date: Thu, 23 Oct 2025 13:24:20 -0600 Subject: [PATCH] [flang][Driver] Warn on -fbuiltin and -fno-builtin The options -fbuiltin and -fno-builtin are not valid for Fortran. However, they are accepted by gfortran which emits a warning message but continues to compile the code. Both -fbuiltin and -fno-builtin have been enabled for flang. Specifying either will result in a warning message being shown but no other effects. Compilation will proceed normally after these warnings are shown. This brings flang's behavior in line with gfortran for these options. Fixes #164766 --- clang/include/clang/Basic/DiagnosticDriverKinds.td | 3 +++ clang/include/clang/Driver/Options.td | 4 ++-- clang/lib/Driver/ToolChains/Flang.cpp | 7 +++++++ 3 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td index 0581bf353d936..83980e3ac35b7 100644 --- a/include/clang/Basic/DiagnosticDriverKinds.td +++ b/include/clang/Basic/DiagnosticDriverKinds.td @@ -131,6 +131,9 @@ def warn_drv_unsupported_option_for_offload_arch_req_feature : Warning< def warn_drv_unsupported_option_for_target : Warning< "ignoring '%0' option as it is not currently supported for target '%1'">, InGroup; +def warn_drv_invalid_argument_for_flang : Warning< + "'%0' is not valid for Fortran">, + InGroup; def warn_drv_unsupported_option_for_flang : Warning< "the argument '%0' is not supported for option '%1'. Mapping to '%1%2'">, InGroup; diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td index ef1c8758705f4..bca8b26bc3d30 100644 --- a/include/clang/Driver/Options.td +++ b/include/clang/Driver/Options.td @@ -1940,7 +1940,7 @@ defm borland_extensions : BoolFOption<"borland-extensions", "Accept non-standard constructs supported by the Borland compiler">, NegFlag>; def fbuiltin : Flag<["-"], "fbuiltin">, Group, - Visibility<[ClangOption, CLOption, DXCOption]>; + Visibility<[ClangOption, CLOption, DXCOption, FlangOption, FC1Option]>; def fbuiltin_module_map : Flag <["-"], "fbuiltin-module-map">, Group, Flags<[]>, HelpText<"Load the clang builtins module map file.">; defm caret_diagnostics : BoolFOption<"caret-diagnostics", @@ -3493,7 +3493,7 @@ def fno_assume_sane_operator_new : Flag<["-"], "fno-assume-sane-operator-new">, HelpText<"Don't assume that C++'s global operator new can't alias any pointer">, Visibility<[ClangOption, CC1Option]>, MarshallingInfoNegativeFlag>; def fno_builtin : Flag<["-"], "fno-builtin">, Group, - Visibility<[ClangOption, CC1Option, CLOption, DXCOption]>, + Visibility<[ClangOption, CC1Option, CLOption, DXCOption, FlangOption, FC1Option]>, HelpText<"Disable implicit builtin knowledge of functions">; def fno_builtin_ : Joined<["-"], "fno-builtin-">, Group, Visibility<[ClangOption, CC1Option, CLOption, DXCOption]>, diff --git a/lib/Driver/ToolChains/Flang.cpp b/lib/Driver/ToolChains/Flang.cpp index a56fa41c49d34..88bce181d40d2 100644 --- a/lib/Driver/ToolChains/Flang.cpp +++ b/lib/Driver/ToolChains/Flang.cpp @@ -851,6 +851,13 @@ void Flang::ConstructJob(Compilation &C, const JobAction &JA, assert(false && "Unexpected action class for Flang tool."); } + // We support some options that are invalid for Fortran and have no effect. + // These are solely for compatibility with other compilers. Emit a warning if + // any such options are provided, then proceed normally. + for (options::ID Opt : {options::OPT_fbuiltin, options::OPT_fno_builtin}) + if (const Arg *A = Args.getLastArg(Opt)) + D.Diag(diag::warn_drv_invalid_argument_for_flang) << A->getSpelling(); + const InputInfo &Input = Inputs[0]; types::ID InputType = Input.getType();