[Driver] Add "did you mean?" suggestions to -cc1as

[modocache]

Summary

In https://reviews.llvm.org/D41733, the driver was modified such that,
when a user provided a mispelled option such as -hel, it would
suggest a valid option with a nearby edit distance: "did you mean
'-help'?".

Add these suggestions to invocations of clang -cc1as as well.

Test Plan: check-clang

[v.g.vassilev]

LGTM!

[modocache]

Thanks, @v.g.vassilev!

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: not %clang %s -stdlibs=foo -hell -version -### 2>&1 | \
 // RUN: FileCheck %s --check-prefix=DID-YOU-MEAN
 // 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: %clang_cl -Brepo -### -- %s 2>&1 | \
 // RUN: FileCheck %s --check-prefix=CL-DID-YOU-MEAN
 // 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-ERROR
 // RUN: not %clang_cl -helo -Werror=unknown-argument -### -- %s 2>&1 | \
 // RUN: FileCheck %s --check-prefix=CL-ERROR-DID-YOU-MEAN
 // 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
+// RUN: not %clang -cc1as -hell --version -debug-info-macros 2>&1 | \
+// RUN: FileCheck %s --check-prefix=CC1AS-DID-YOU-MEAN
 
 // CHECK: error: unknown argument: '-cake-is-lie'
 // CHECK: error: unknown argument: '-%0'
 // CHECK: error: unknown argument: '-%d'
 // CHECK: error: unknown argument: '-HHHH'
 // CHECK: error: unknown argument: '-munknown-to-clang-option'
 // CHECK: error: unknown argument: '-print-stats'
 // CHECK: error: unknown argument: '-funknown-to-clang-option'

 // CL-ERROR: error: unknown argument ignored in clang-cl: '-%d'
 // CL-ERROR: error: unknown argument ignored in clang-cl: '-HHHH'
 // CL-ERROR: error: unknown argument ignored in clang-cl: '-munknown-to-clang-option'
 // CL-ERROR: error: unknown argument ignored in clang-cl: '-print-stats'
 // CL-ERROR: error: unknown argument ignored in clang-cl: '-funknown-to-clang-option'
 // CL-ERROR-DID-YOU-MEAN: error: unknown argument ignored in clang-cl '-helo' (did you mean '-help'?)
 // SILENT-NOT: error:
 // SILENT-NOT: warning:
+// CC1AS-DID-YOU-MEAN: error: unknown argument '-hell', did you mean '-help'?
+// CC1AS-DID-YOU-MEAN: error: unknown argument '--version', did you mean '-version'?
+// CC1AS-DID-YOU-MEAN: error: unknown argument '-debug-info-macros', did you mean '-debug-info-macro'?
 
 
 // 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'

tools/driver/cc1as_main.cpp

bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
   if (MissingArgCount) {
     Diags.Report(diag::err_drv_missing_argument)
         << Args.getArgString(MissingArgIndex) << MissingArgCount;
     Success = false;
   }
 
   // Issue errors on unknown arguments.
   for (const Arg *A : Args.filtered(OPT_UNKNOWN)) {
-    Diags.Report(diag::err_drv_unknown_argument) << A->getAsString(Args);
+    auto ArgString = A->getAsString(Args);
+    std::string Nearest;
+    if (OptTbl->findNearest(ArgString, Nearest, IncludedFlagsBitmask) > 1)
+      Diags.Report(diag::err_drv_unknown_argument) << ArgString;
+    else
+      Diags.Report(diag::err_drv_unknown_argument_with_suggestion)
+          << ArgString << Nearest;
     Success = false;
   }
 
   // Construct the invocation.
 
   // Target Options
   Opts.Triple = llvm::Triple::normalize(Args.getLastArgValue(OPT_triple));
   Opts.CPU = Args.getLastArgValue(OPT_target_cpu);