[flang] Handle unsupported warning flags

This PR makes flang emit a warning when the user passes an unsupported gfortran warning flag in as a CLI arg.  This PR also checks each `-W` argument instead of just looking at the last one passed in.

Reviewed By: awarzynski

Differential Revision: https://reviews.llvm.org/D143301

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -113,6 +113,9 @@ def warn_drv_unsupported_option_for_target : Warning<
 def warn_drv_unsupported_option_for_flang : Warning<
   "the argument '%0' is not supported for option '%1'. Mapping to '%1%2'">,
   InGroup<OptionIgnored>;
+def warn_drv_unsupported_diag_option_for_flang : Warning<
+  "The warning option '-%0' is not supported">,
+  InGroup<OptionIgnored>;
 
 def err_drv_invalid_thread_model_for_target : Error<
   "invalid thread model '%0' in '%1' for this target">;

clang/include/clang/Driver/Options.td

@@ -235,6 +235,10 @@ def clang_ignored_f_Group : OptionGroup<"<clang ignored f group>">,
 def clang_ignored_m_Group : OptionGroup<"<clang ignored m group>">,
   Group<m_Group>, Flags<[Ignored]>;
 
+// Unsupported flang groups
+def flang_ignored_w_Group : OptionGroup<"<flang ignored W group>">,
+  Group<W_Group>, Flags<[FlangOnlyOption, Ignored]>;
+
 // Group for clang options in the process of deprecation.
 // Please include the version that deprecated the flag as comment to allow
 // easier garbage collection.
@@ -4871,6 +4875,10 @@ multiclass BooleanFFlag<string name> {
   def fno_#NAME : Flag<["-"], "fno-"#name>;
 }
 
+multiclass FlangIgnoredDiagOpt<string name> {
+  def unsupported_warning_w#NAME : Flag<["-", "--"], "W"#name>, Group<flang_ignored_w_Group>;
+}
+
 defm : BooleanFFlag<"keep-inline-functions">, Group<clang_ignored_gcc_optimization_f_Group>;
 
 def fprofile_dir : Joined<["-"], "fprofile-dir=">, Group<f_Group>;
@@ -5030,6 +5038,36 @@ defm second_underscore : BooleanFFlag<"second-underscore">, Group<gfortran_Group
 defm sign_zero : BooleanFFlag<"sign-zero">, Group<gfortran_Group>;
 defm whole_file : BooleanFFlag<"whole-file">, Group<gfortran_Group>;
 
+// -W <arg> options unsupported by the flang compiler
+// If any of these options are passed into flang's compiler driver,
+// a warning will be raised and the argument will be claimed
+defm : FlangIgnoredDiagOpt<"extra">;
+defm : FlangIgnoredDiagOpt<"aliasing">;
+defm : FlangIgnoredDiagOpt<"ampersand">;
+defm : FlangIgnoredDiagOpt<"array-bounds">;
+defm : FlangIgnoredDiagOpt<"c-binding-type">;
+defm : FlangIgnoredDiagOpt<"character-truncation">;
+defm : FlangIgnoredDiagOpt<"conversion">;
+defm : FlangIgnoredDiagOpt<"do-subscript">;
+defm : FlangIgnoredDiagOpt<"function-elimination">;
+defm : FlangIgnoredDiagOpt<"implicit-interface">;
+defm : FlangIgnoredDiagOpt<"implicit-procedure">;
+defm : FlangIgnoredDiagOpt<"intrinsic-shadow">;
+defm : FlangIgnoredDiagOpt<"use-without-only">;
+defm : FlangIgnoredDiagOpt<"intrinsics-std">;
+defm : FlangIgnoredDiagOpt<"line-truncation">;
+defm : FlangIgnoredDiagOpt<"no-align-commons">;
+defm : FlangIgnoredDiagOpt<"no-overwrite-recursive">;
+defm : FlangIgnoredDiagOpt<"no-tabs">;
+defm : FlangIgnoredDiagOpt<"real-q-constant">;
+defm : FlangIgnoredDiagOpt<"surprising">;
+defm : FlangIgnoredDiagOpt<"underflow">;
+defm : FlangIgnoredDiagOpt<"unused-parameter">;
+defm : FlangIgnoredDiagOpt<"realloc-lhs">;
+defm : FlangIgnoredDiagOpt<"realloc-lhs-all">;
+defm : FlangIgnoredDiagOpt<"frontend-loop-interchange">;
+defm : FlangIgnoredDiagOpt<"target-lifetime">;
+
 // C++ SYCL options
 def fsycl : Flag<["-"], "fsycl">, Flags<[NoXarchOption, CoreOption]>,
   Group<sycl_Group>, HelpText<"Enables SYCL kernels compilation for device">;

clang/lib/Driver/ToolChains/Flang.cpp

@@ -329,6 +329,13 @@ void Flang::ConstructJob(Compilation &C, const JobAction &JA,
     A->render(Args, CmdArgs);
   }
 
+  // Remove any unsupported gfortran diagnostic options
+  for (const Arg *A : Args.filtered(options::OPT_flang_ignored_w_Group)) {
+    A->claim();
+    D.Diag(diag::warn_drv_unsupported_diag_option_for_flang)
+        << A->getOption().getName();
+  }
+
   // Optimization level for CodeGen.
   if (const Arg *A = Args.getLastArg(options::OPT_O_Group)) {
     if (A->getOption().matches(options::OPT_O4)) {

flang/docs/FlangDriver.md

@@ -581,6 +581,10 @@ floating point and so always acts as though these flags were specified.
 GCC/GFortran will also set flush-to-zero mode: linking `crtfastmath.o`, the same
 as Flang.
 
+The only GCC/GFortran warning option currently supported is `-Werror`.  Passing
+any unsupported GCC/GFortran warning flags into Flang's compiler driver will
+result in warnings being emitted.
+
 ### Comparison with nvfortran
 nvfortran defines `-fast` as
 `-O2 -Munroll=c:1 -Mnoframe -Mlre -Mpre -Mvect=simd -Mcache_align -Mflushz -Mvect`.

flang/lib/Frontend/CompilerInvocation.cpp

@@ -610,14 +610,17 @@ static bool parseDiagArgs(CompilerInvocation &res, llvm::opt::ArgList &args,
   // TODO: Currently throws a Diagnostic for anything other than -W<error>,
   // this has to change when other -W<opt>'s are supported.
   if (args.hasArg(clang::driver::options::OPT_W_Joined)) {
-    if (args.getLastArgValue(clang::driver::options::OPT_W_Joined)
-            .equals("error")) {
-      res.setWarnAsErr(true);
-    } else {
-      const unsigned diagID =
-          diags.getCustomDiagID(clang::DiagnosticsEngine::Error,
-                                "Only `-Werror` is supported currently.");
-      diags.Report(diagID);
+    const auto &wArgs =
+        args.getAllArgValues(clang::driver::options::OPT_W_Joined);
+    for (const auto &wArg : wArgs) {
+      if (wArg == "error") {
+        res.setWarnAsErr(true);
+      } else {
+        const unsigned diagID =
+            diags.getCustomDiagID(clang::DiagnosticsEngine::Error,
+                                  "Only `-Werror` is supported currently.");
+        diags.Report(diagID);
+      }
     }
   }
 

flang/test/Driver/w-arg-unsupported.f90

@@ -0,0 +1,37 @@
+! RUN: %flang -std=f2018 -Wextra -Waliasing -Wampersand -Warray-bounds -Wc-binding-type \
+! RUN:        -Wcharacter-truncation -Wconversion -Wdo-subscript -Wfunction-elimination \
+! RUN:        -Wimplicit-interface -Wimplicit-procedure -Wintrinsic-shadow -Wuse-without-only \
+! RUN:        -Wintrinsics-std -Wline-truncation -Wno-align-commons -Wno-overwrite-recursive \
+! RUN:        -Wno-tabs -Wreal-q-constant -Wsurprising -Wunderflow -Wunused-parameter \
+! RUN:        -Wrealloc-lhs -Wrealloc-lhs-all -Wfrontend-loop-interchange -Wtarget-lifetime %s \
+! RUN:        2>&1 | FileCheck %s
+
+! CHECK: The warning option '-Wextra' is not supported
+! CHECK-NEXT: The warning option '-Waliasing' is not supported
+! CHECK-NEXT: The warning option '-Wampersand' is not supported
+! CHECK-NEXT: The warning option '-Warray-bounds' is not supported
+! CHECK-NEXT: The warning option '-Wc-binding-type' is not supported
+! CHECK-NEXT: The warning option '-Wcharacter-truncation' is not supported
+! CHECK-NEXT: The warning option '-Wconversion' is not supported
+! CHECK-NEXT: The warning option '-Wdo-subscript' is not supported
+! CHECK-NEXT: The warning option '-Wfunction-elimination' is not supported
+! CHECK-NEXT: The warning option '-Wimplicit-interface' is not supported
+! CHECK-NEXT: The warning option '-Wimplicit-procedure' is not supported
+! CHECK-NEXT: The warning option '-Wintrinsic-shadow' is not supported
+! CHECK-NEXT: The warning option '-Wuse-without-only' is not supported
+! CHECK-NEXT: The warning option '-Wintrinsics-std' is not supported
+! CHECK-NEXT: The warning option '-Wline-truncation' is not supported
+! CHECK-NEXT: The warning option '-Wno-align-commons' is not supported
+! CHECK-NEXT: The warning option '-Wno-overwrite-recursive' is not supported
+! CHECK-NEXT: The warning option '-Wno-tabs' is not supported
+! CHECK-NEXT: The warning option '-Wreal-q-constant' is not supported
+! CHECK-NEXT: The warning option '-Wsurprising' is not supported
+! CHECK-NEXT: The warning option '-Wunderflow' is not supported
+! CHECK-NEXT: The warning option '-Wunused-parameter' is not supported
+! CHECK-NEXT: The warning option '-Wrealloc-lhs' is not supported
+! CHECK-NEXT: The warning option '-Wrealloc-lhs-all' is not supported
+! CHECK-NEXT: The warning option '-Wfrontend-loop-interchange' is not supported
+! CHECK-NEXT: The warning option '-Wtarget-lifetime' is not supported
+
+program m
+end program

flang/test/Driver/werror-all.f90

@@ -0,0 +1,13 @@
+! Ensures that -Werror is read regardless of whether or not other -W
+! flags are present in the CLI args
+
+! RUN: not %flang -std=f2018 -Werror -Wextra %s 2>&1 | FileCheck %s --check-prefix=WRONG
+! RUN: %flang -std=f2018 -Wextra -Wall %s 2>&1 | FileCheck %s --check-prefix=CHECK-OK
+
+! WRONG: Semantic errors in
+! CHECK-OK: FORALL index variable
+
+program werror_check_all
+  integer :: a(3)
+  forall (j=1:n) a(i) = 1
+end program werror_check_all

flang/test/Driver/wextra-ok.f90

@@ -0,0 +1,11 @@
+! Ensure that supplying -Wextra into flang-new does not raise error
+! The first check should be changed if -Wextra is implemented
+
+! RUN: %flang -std=f2018 -Wextra %s 2>&1 | FileCheck %s --check-prefix=CHECK-OK
+! RUN: not %flang -std=f2018 -Wblah -Wextra %s 2>&1 | FileCheck %s --check-prefix=WRONG
+
+! CHECK-OK: The warning option '-Wextra' is not supported
+! WRONG: Only `-Werror` is supported currently.
+
+program wextra_ok
+end program wextra_ok