[Driver] Don't warn about unused inputs in config files

[mstorsjo]

Summary

This avoids warnings about unused linker parameters, just like other flags are ignored if they're from config files.

[sepavloff]

Indeed, this is a missing case. Thank you for fixing it!

LGTM

[mstorsjo]

In order not to break test/Driver/cl-pch.cpp (I hadn't run the full testsuite for this change before submitting the patch), I had to do another tweak, in order not to claim any input argument after --. Does it still sound ok to you @sepavloff?

[mstorsjo]

@sepavloff - does the additional change to this one also look fine to you?

[sepavloff]

With additional changes the fix is OK.

LGTM.

lib/Driver/Driver.cpp

phases::ID Driver::getFinalPhase(const DerivedArgList &DAL,
 
   if (FinalPhaseArg)
     *FinalPhaseArg = PhaseArg;
 
   return FinalPhase;
 }
 
 static Arg *MakeInputArg(DerivedArgList &Args, OptTable &Opts,
-                         StringRef Value) {
+                         StringRef Value, bool Claim = true) {
   Arg *A = new Arg(Opts.getOption(options::OPT_INPUT), Value,
                    Args.getBaseArgs().MakeIndex(Value), Value.data());
   Args.AddSynthesizedArg(A);
+  if (Claim)
     A->claim();
   return A;
 }
 
 DerivedArgList *Driver::TranslateInputArgs(const InputArgList &Args) const {
   DerivedArgList *DAL = new DerivedArgList(Args);
 
   bool HasNostdlib = Args.hasArg(options::OPT_nostdlib);
   bool HasNodefaultlib = Args.hasArg(options::OPT_nodefaultlibs);
if (A->getOption().matches(options::OPT_l)) {
         continue;
       }
     }
 
     // Pick up inputs via the -- option.
     if (A->getOption().matches(options::OPT__DASH_DASH)) {
       A->claim();
       for (StringRef Val : A->getValues())
-        DAL->append(MakeInputArg(*DAL, *Opts, Val));
+        DAL->append(MakeInputArg(*DAL, *Opts, Val, false));
       continue;
     }
 
     DAL->append(A);
   }
 
   // Enforce -static if -miamcu is present.
   if (Args.hasFlag(options::OPT_miamcu, options::OPT_mno_iamcu, false))
for (auto &I : Inputs) {
 
     PL.clear();
     types::getCompilationPhases(InputType, PL);
 
     // If the first step comes after the final phase we are doing as part of
     // this compilation, warn the user about it.
     phases::ID InitialPhase = PL[0];
     if (InitialPhase > FinalPhase) {
+      if (InputArg->isClaimed())
+        continue;
+
       // Claim here to avoid the more general unused warning.
       InputArg->claim();
 
       // Suppress all unused style warnings with -Qunused-arguments
       if (Args.hasArg(options::OPT_Qunused_arguments))
         continue;
 
       // Special case when final phase determined by binary name, rather than

test/Driver/Inputs/config-4.cfg

 -L/usr/local/lib
--stdlib=libc++
+-lfoo
+-stdlib=libc++

test/Driver/config-file.c

 // CHECK-NESTED2a: -isysroot
 // CHECK-NESTED2a-SAME: /opt/data
 
 
 //--- Unused options in config file do not produce warnings
 //
 // RUN: %clang --config %S/Inputs/config-4.cfg -S %s -o /dev/null -v 2>&1 | FileCheck %s -check-prefix CHECK-UNUSED
 // CHECK-UNUSED-NOT: argument unused during compilation:
+// CHECK-UNUSED-NOT: 'linker' input unused
 
 
 //--- User directory is searched first.
 //
 // RUN: %clang --config-system-dir=%S/Inputs/config --config-user-dir=%S/Inputs/config2 --config config-4 -S %s -o /dev/null -v 2>&1 | FileCheck %s -check-prefix CHECK-PRECEDENCE
 // CHECK-PRECEDENCE: Configuration file: {{.*}}Inputs{{.}}config2{{.}}config-4.cfg
 // CHECK-PRECEDENCE: -Wall