[MSVC Compat] Only warn for unknown clang-cl arguments

[• ehsan]

Summary

MSVC's driver accepts all unknown arguments but warns about them. clang
by default rejects all unknown arguments. This causes issues
specifically with build systems such as autoconf which liberally pass
things such as $LDFLAGS to the compiler and expect everything to work.
This patch teaches clang-cl to ignore unknown driver arguments.

[rnk]

lgtm other than the warning group.

test/Misc/warning-flags.c

21 ↗

(On Diff #45796)

This list shouldn't grow, we should have a warning group for this. -W[no-]unknown-argument sounds good to me.

[hans]

Maybe this behavior should be called out in the Command-Line Options section under clang-cl in docs/UsersManual.rst?

[• ehsan]

Thanks for the reviews! Will address both when landing.

cfe/trunk/docs/UsersManual.rst

 with a warning. For example:
 
   ::
 
     clang-cl.exe: warning: argument unused during compilation: '/AI'
 
 To suppress warnings about unused arguments, use the ``-Qunused-arguments`` option.
 
-Options that are not known to clang-cl will cause errors. If they are spelled with a
-leading ``/``, they will be mistaken for a filename:
+Options that are not known to clang-cl will be ignored by default. Use the
+``-Werror=unknown-argument`` option in order to treat them as errors. If these
+options are spelled with a leading ``/``, they will be mistaken for a filename:
 
   ::
 
     clang-cl.exe: error: no such file or directory: '/foobar'
 
 Please `file a bug <http://llvm.org/bugs/enter_bug.cgi?product=clang&component=Driver>`_
 for any valid cl.exe flags that clang-cl does not understand.
 

cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td

def err_drv_malformed_sanitizer_blacklist : Error<
   "malformed sanitizer blacklist: '%0'">;
 
 def err_target_unsupported_arch
   : Error<"the target architecture '%0' is not supported by the target '%1'">;
 
 def err_drv_I_dash_not_supported : Error<
   "'%0' not supported, please use -iquote instead">;
 def err_drv_unknown_argument : Error<"unknown argument: '%0'">;
+def warn_drv_unknown_argument_clang_cl : Warning<
+  "unknown argument ignored in clang-cl: '%0'">,
+  InGroup<UnknownArgument>;
 def err_drv_invalid_value : Error<"invalid value '%1' in '%0'">;
 def err_drv_invalid_int_value : Error<"invalid integral value '%1' in '%0'">;
 def err_drv_invalid_remap_file : Error<
     "invalid option '%0' not of the form <from-file>;<to-file>">;
 def err_drv_invalid_gcc_output_type : Error<
     "invalid output type '%0' for use with gcc tool">;
 def err_drv_cc_print_options_failure : Error<
     "unable to open CC_PRINT_OPTIONS file: %0">;

cfe/trunk/include/clang/Basic/DiagnosticGroups.td

 def CudaCompat : DiagGroup<"cuda-compat">;
 
 // A warning group for things that will change semantics in the future.
 def FutureCompat : DiagGroup<"future-compat">;
 
 def InvalidOrNonExistentDirectory : DiagGroup<"invalid-or-nonexistent-directory">;
 
 def OptionIgnored : DiagGroup<"option-ignored">;
+
+def UnknownArgument : DiagGroup<"unknown-argument">;

cfe/trunk/lib/Driver/Driver.cpp

for (const Arg *A : Args) {
 
     // Warn about -mcpu= without an argument.
     if (A->getOption().matches(options::OPT_mcpu_EQ) && A->containsValue("")) {
       Diag(clang::diag::warn_drv_empty_joined_argument) << A->getAsString(Args);
     }
   }
 
   for (const Arg *A : Args.filtered(options::OPT_UNKNOWN))
-    Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
+    Diags.Report(IsCLMode() ? diag::warn_drv_unknown_argument_clang_cl :
+                              diag::err_drv_unknown_argument)
+      << A->getAsString(Args);
 
   return Args;
 }
 
 // Determine which compilation mode we are in. We look for options which
 // affect the phase, starting with the earliest phases, and record which
 // option we used to determine the final phase.
 phases::ID Driver::getFinalPhase(const DerivedArgList &DAL,
if (!A->isClaimed()) {
             break;
           }
         }
 
         if (DuplicateClaimed)
           continue;
       }
 
+      // In clang-cl, don't mention unknown arguments here since they have
+      // already been warned about.
+      if (!IsCLMode() || !A->getOption().matches(options::OPT_UNKNOWN))
         Diag(clang::diag::warn_drv_unused_argument)
             << A->getAsString(C.getArgs());
     }
   }
 }
 
 // Returns a Tool for a given JobAction.  In case the action and its
 // predecessors can be combined, updates Inputs with the inputs of the
 // first combined action. If one of the collapsed actions is a
 // CudaHostAction, updates CollapsedCHA with the pointer to it so the

cfe/trunk/lib/Driver/Tools.cpp

std::unique_ptr<Command> visualstudio::Compiler::GetCommand(
   Args.AddAllArgs(CmdArgs, options::OPT__SLASH_EH);
   Args.AddAllArgs(CmdArgs, options::OPT__SLASH_Zl);
 
   // The order of these flags is relevant, so pick the last one.
   if (Arg *A = Args.getLastArg(options::OPT__SLASH_MD, options::OPT__SLASH_MDd,
                                options::OPT__SLASH_MT, options::OPT__SLASH_MTd))
     A->render(Args, CmdArgs);
 
+  // Pass through all unknown arguments so that the fallback command can see
+  // them too.
+  Args.AddAllArgs(CmdArgs, options::OPT_UNKNOWN);
+
   // Input filename.
   assert(Inputs.size() == 1);
   const InputInfo &II = Inputs[0];
   assert(II.getType() == types::TY_C || II.getType() == types::TY_CXX);
   CmdArgs.push_back(II.getType() == types::TY_C ? "/Tc" : "/Tp");
   if (II.isFilename())
     CmdArgs.push_back(II.getFilename());
   else

cfe/trunk/test/Driver/cl-fallback.c

 // Note: %s must be preceded by --, otherwise it may be interpreted as a
 // command-line option, e.g. on Mac where %s is commonly under /Users.
 
 // RUN: %clang_cl --target=i686-pc-win32 /fallback /Dfoo=bar /Ubaz /Ifoo /O0 /Ox /GR /GR- /Gy /Gy- \
 // RUN:   /Gw /Gw- /LD /LDd /EHs /EHs- /Zl /MD /MDd /MTd /MT /FImyheader.h /Zi \
+// RUN:   -garbage -moregarbage \
 // RUN:   -### -- %s 2>&1 \
 // RUN:   | FileCheck %s
 // CHECK: "-fdiagnostics-format" "msvc-fallback"
 // CHECK: ||
 // CHECK: cl.exe
 // CHECK: "/nologo"
 // CHECK: "/c"
 // CHECK: "/W0"

 // CHECK: "/Z7"
 // CHECK: "/FImyheader.h"
 // CHECK: "/LD"
 // CHECK: "/LDd"
 // CHECK: "/EHs"
 // CHECK: "/EHs-"
 // CHECK: "/Zl"
 // CHECK: "/MT"
+// CHECK: "-garbage"
+// CHECK: "-moregarbage"
 // CHECK: "/Tc" "{{.*cl-fallback.c}}"
 // CHECK: "/Fo{{.*cl-fallback.*.obj}}"
 
 // RUN: %clang_cl /fallback /GR- -### -- %s 2>&1 | FileCheck -check-prefix=GR %s
 // GR: cl.exe
 // GR: "/GR-"
 
 // RUN: %clang_cl /fallback /Od -### -- %s 2>&1 | FileCheck -check-prefix=O0 %s

cfe/trunk/test/Driver/unknown-arg.c

 // RUN: not %clang %s -cake-is-lie -%0 -%d -HHHH -munknown-to-clang-option -print-stats -funknown-to-clang-option 2>&1 | \
 // RUN: FileCheck %s
+// RUN: %clang_cl -cake-is-lie -%0 -%d -HHHH -munknown-to-clang-option -print-stats -funknown-to-clang-option -c -- %s 2>&1 | \
+// RUN: FileCheck %s --check-prefix=CL
+// RUN: not %clang_cl -cake-is-lie -%0 -%d -HHHH -munknown-to-clang-option -print-stats -funknown-to-clang-option -c -Werror=unknown-argument -- %s 2>&1 | \
+// RUN: FileCheck %s --check-prefix=CL
+// RUN: %clang_cl -cake-is-lie -%0 -%d -HHHH -munknown-to-clang-option -print-stats -funknown-to-clang-option -c -Wno-unknown-argument -- %s 2>&1 | \
+// RUN: FileCheck %s --check-prefix=SILENT --allow-empty
 
 // CHECK: unknown argument: '-cake-is-lie'
 // CHECK: unknown argument: '-%0'
 // CHECK: unknown argument: '-%d'
 // CHECK: unknown argument: '-HHHH'
 // CHECK: unknown argument: '-munknown-to-clang-option'
 // CHECK: unknown argument: '-print-stats'
 // CHECK: unknown argument: '-funknown-to-clang-option'
+// CL: unknown argument ignored in clang-cl: '-cake-is-lie'
+// CL: unknown argument ignored in clang-cl: '-%0'
+// CL: unknown argument ignored in clang-cl: '-%d'
+// CL: unknown argument ignored in clang-cl: '-HHHH'
+// CL: unknown argument ignored in clang-cl: '-munknown-to-clang-option'
+// CL: unknown argument ignored in clang-cl: '-print-stats'
+// CL: unknown argument ignored in clang-cl: '-funknown-to-clang-option'
+// SILENT-NOT: error
+// SILENT-NOT: warning
 
 
 // RUN: %clang -S %s -o %t.s  -Wunknown-to-clang-option 2>&1 | FileCheck --check-prefix=IGNORED %s
 
 // IGNORED: warning: unknown warning option '-Wunknown-to-clang-option'

cfe/trunk/test/Misc/serialized-diags-driver.c

 // Test that the driver correctly combines its own diagnostics with CC1's in the
 // serialized diagnostics. To test this, we need to trigger diagnostics from
 // both processes, so we compile code that has a warning (with an associated
 // note) and then force the driver to crash. We compile stdin so that the crash
 // doesn't litter the user's system with preprocessed output.
 
 // RUN: rm -f %t
-// RUN: %clang -Wx-unknown-warning -Wall -fsyntax-only --serialize-diagnostics %t.diag %s
+// RUN: %clang -Wx-typoed-warning -Wall -fsyntax-only --serialize-diagnostics %t.diag %s
 // RUN: c-index-test -read-diagnostics %t.diag 2>&1 | FileCheck %s
 
-// CHECK: warning: unknown warning option '-Wx-unknown-warning' [-Wunknown-warning-option] []
+// CHECK: warning: unknown warning option '-Wx-typoed-warning' [-Wunknown-warning-option] []
 
 // CHECK: warning: variable 'voodoo' is uninitialized when used here [-Wuninitialized]
 // CHECK: note: initialize the variable 'voodoo' to silence this warning []
 // CHECK: Number of diagnostics: 2
 
 void foo() {
   int voodoo;
   voodoo = voodoo + 1;
 }