[Driver] Fix driver support for color diagnostics

[bruno]

Summary

Diagnostics that happen during driver time do not have color output
support unless -fcolor-diagonostic is explicitly passed into the driver.
OTOH, it works great for cc1 mode since dianostic arguments are properly
handled and color is enabled by default if the terminal supports it.

This patch fix this behavior by using the same logic present in -cc1
argument construction to decide whether it should use colors. I tried to
find a way to refactor this logic into a common place that could be used
from both lib/Driver/Tools.cpp and lib/Frontend/CompilerInvocation.cpp,
but could not see any options besides libBasic, which also seems wrong
because it's not the ideal place to put options parsing code either. So
I duplicated part of the logic and changed some driver unrelated logic.
(look for ShowColors in lib/Driver/Tools.cpp for details). Ideas welcome.

I do not see a way to write a testcase for this.

[silvas]

I don't see an issue with putthing this as a helper in libBasic. We may need to add a libOption dependency to it but that sounds fine.

[dexonsmith]

I don't think we even need a helper.

Clang::ConstructJob takes a Compilation, which has a Driver, which has a DiagnosticsEngine, which has a DiagnosticsOptions.

In other words, I think you can delete the code in Clang::ConstructJob (change it to a lookup) now that you've changed clang::ParseDiagnosticArgs to update DiagnosticsOptions.

[bruno]

Great idea Duncan, attached a new patch!

[bruno]

Ping!

[bruno]

Ping!

[dexonsmith]

LGTM.

[bruno]

Committed in r271042

include/clang/Frontend/CompilerInvocation.h

 /// When errors are encountered, return false and, if Diags is non-null,
 /// report the error(s).
 bool ParseDiagnosticArgs(DiagnosticOptions &Opts, llvm::opt::ArgList &Args,
-                         DiagnosticsEngine *Diags = nullptr);
+                         DiagnosticsEngine *Diags = nullptr,
+                         bool DefaultDiagColor = true);
 
 class CompilerInvocationBase : public RefCountedBase<CompilerInvocation> {
   void operator=(const CompilerInvocationBase &) = delete;

lib/Driver/Tools.cpp

       CmdArgs.push_back("-fno-diagnostics-show-note-include-stack");
   }
 
-  // Color diagnostics are the default, unless the terminal doesn't support
-  // them.
-  // Support both clang's -f[no-]color-diagnostics and gcc's
-  // -f[no-]diagnostics-colors[=never|always|auto].
-  enum { Colors_On, Colors_Off, Colors_Auto } ShowColors = Colors_Auto;
-  for (const auto &Arg : Args) {
-    const Option &O = Arg->getOption();
+  // Color diagnostics are parsed by the driver directly from argv
+  // and later re-parsed to construct this job; claim any possible
+  // color diagnostic here to avoid warn_drv_unused_argument and
+  // diagnose bad OPT_fdiagnostics_color_EQ values.
+  for (Arg *A : Args) {
+    const Option &O = A->getOption();
     if (!O.matches(options::OPT_fcolor_diagnostics) &&
         !O.matches(options::OPT_fdiagnostics_color) &&
         !O.matches(options::OPT_fno_color_diagnostics) &&
         !O.matches(options::OPT_fno_diagnostics_color) &&
         !O.matches(options::OPT_fdiagnostics_color_EQ))
       continue;
-
-    Arg->claim();
-    if (O.matches(options::OPT_fcolor_diagnostics) ||
-        O.matches(options::OPT_fdiagnostics_color)) {
-      ShowColors = Colors_On;
-    } else if (O.matches(options::OPT_fno_color_diagnostics) ||
-               O.matches(options::OPT_fno_diagnostics_color)) {
-      ShowColors = Colors_Off;
-    } else {
-      assert(O.matches(options::OPT_fdiagnostics_color_EQ));
-      StringRef value(Arg->getValue());
-      if (value == "always")
-        ShowColors = Colors_On;
-      else if (value == "never")
-        ShowColors = Colors_Off;
-      else if (value == "auto")
-        ShowColors = Colors_Auto;
-      else
+    if (O.matches(options::OPT_fdiagnostics_color_EQ)) {
+      StringRef Value(A->getValue());
+      if (Value != "always" && Value != "never" && Value != "auto")
         getToolChain().getDriver().Diag(diag::err_drv_clang_unsupported)
-            << ("-fdiagnostics-color=" + value).str();
+              << ("-fdiagnostics-color=" + Value).str();
     }
+    A->claim();
   }
-  if (ShowColors == Colors_On ||
-      (ShowColors == Colors_Auto && llvm::sys::Process::StandardErrHasColors()))
+  if (D.getDiags().getDiagnosticOptions().ShowColors)
     CmdArgs.push_back("-fcolor-diagnostics");
 
   if (Args.hasArg(options::OPT_fansi_escape_codes))

lib/Frontend/CompilerInvocation.cpp

                         ModuleFiles.end());
 }
 
+static bool parseShowColorsArgs(const ArgList &Args, bool DefaultColor) {
+  // Color diagnostics default to auto ("on" if terminal supports) in the driver
+  // but default to off in cc1, needing an explicit OPT_fdiagnostics_color.
+  // Support both clang's -f[no-]color-diagnostics and gcc's
+  // -f[no-]diagnostics-colors[=never|always|auto].
+  enum {
+    Colors_On,
+    Colors_Off,
+    Colors_Auto
+  } ShowColors = DefaultColor ? Colors_Auto : Colors_Off;
+  for (Arg *A : Args) {
+    const Option &O = A->getOption();
+    if (!O.matches(options::OPT_fcolor_diagnostics) &&
+        !O.matches(options::OPT_fdiagnostics_color) &&
+        !O.matches(options::OPT_fno_color_diagnostics) &&
+        !O.matches(options::OPT_fno_diagnostics_color) &&
+        !O.matches(options::OPT_fdiagnostics_color_EQ))
+      continue;
+
+    if (O.matches(options::OPT_fcolor_diagnostics) ||
+        O.matches(options::OPT_fdiagnostics_color)) {
+      ShowColors = Colors_On;
+    } else if (O.matches(options::OPT_fno_color_diagnostics) ||
+               O.matches(options::OPT_fno_diagnostics_color)) {
+      ShowColors = Colors_Off;
+    } else {
+      assert(O.matches(options::OPT_fdiagnostics_color_EQ));
+      StringRef Value(A->getValue());
+      if (Value == "always")
+        ShowColors = Colors_On;
+      else if (Value == "never")
+        ShowColors = Colors_Off;
+      else if (Value == "auto")
+        ShowColors = Colors_Auto;
+    }
+  }
+  if (ShowColors == Colors_On ||
+      (ShowColors == Colors_Auto && llvm::sys::Process::StandardErrHasColors()))
+    return true;
+  return false;
+}
+
 bool clang::ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
-                                DiagnosticsEngine *Diags) {
+                                DiagnosticsEngine *Diags,
+                                bool DefaultDiagColor) {
   using namespace options;
   bool Success = true;
 

   Opts.Pedantic = Args.hasArg(OPT_pedantic);
   Opts.PedanticErrors = Args.hasArg(OPT_pedantic_errors);
   Opts.ShowCarets = !Args.hasArg(OPT_fno_caret_diagnostics);
-  Opts.ShowColors = Args.hasArg(OPT_fcolor_diagnostics);
+  Opts.ShowColors = parseShowColorsArgs(Args, DefaultDiagColor);
   Opts.ShowColumn = Args.hasFlag(OPT_fshow_column,
                                  OPT_fno_show_column,
                                  /*Default=*/true);

   Success &= ParseAnalyzerArgs(*Res.getAnalyzerOpts(), Args, Diags);
   Success &= ParseMigratorArgs(Res.getMigratorOpts(), Args);
   ParseDependencyOutputArgs(Res.getDependencyOutputOpts(), Args);
-  Success &= ParseDiagnosticArgs(Res.getDiagnosticOpts(), Args, &Diags);
+  Success &= ParseDiagnosticArgs(Res.getDiagnosticOpts(), Args, &Diags,
+                                 false /*DefaultDiagColor*/);
   ParseCommentArgs(LangOpts.CommentOpts, Args);
   ParseFileSystemArgs(Res.getFileSystemOpts(), Args);
   // FIXME: We shouldn't have to pass the DashX option around here