[Diagnostics] -suppress-warnings and -warnings-as-errors flags

Exposes the global warning suppression and treatment as errors
functionality to the Swift driver. Introduces the flags
"-suppress-warnings" and "-warnings-as-errors". Test case include.

include/swift/AST/DiagnosticEngine.h

@@ -399,7 +399,7 @@ namespace swift {
     bool showDiagnosticsAfterFatalError = false;
 
     /// \brief Don't emit any warnings
-    bool ignoreAllWarnings = false;
+    bool suppressWarnings = false;
 
     /// \brief Emit all warnings as errors
     bool warningsAsErrors = false;
@@ -431,8 +431,8 @@ namespace swift {
     }
 
     /// \brief Whether to skip emitting warnings
-    void setIgnoreAllWarnings(bool val) { ignoreAllWarnings = val; }
+    void setSuppressWarnings(bool val) { suppressWarnings = val; }
-    bool getIgnoreAllWarnings() const { return ignoreAllWarnings; }
+    bool getSuppressWarnings() const { return suppressWarnings; }
 
     /// \brief Whether to treat warnings as errors
     void setWarningsAsErrors(bool val) { warningsAsErrors = val; }
@@ -506,9 +506,9 @@ namespace swift {
     }
 
     /// \brief Whether to skip emitting warnings
-    void setIgnoreAllWarnings(bool val) { state.setIgnoreAllWarnings(val); }
+    void setSuppressWarnings(bool val) { state.setSuppressWarnings(val); }
-    bool getIgnoreAllWarnings() const {
+    bool getSuppressWarnings() const {
-      return state.getIgnoreAllWarnings();
+      return state.getSuppressWarnings();
     }
 
     /// \brief Whether to treat warnings as errors

include/swift/AST/DiagnosticsDriver.def

@@ -115,6 +115,10 @@ ERROR(error_input_changed_during_build,none,
       "input file '%0' was modified during the build",
       (StringRef))
 
+ERROR(error_conflicting_options, none,
+      "conflicting options '%0' and '%1'",
+      (StringRef, StringRef))
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

include/swift/Basic/DiagnosticOptions.h

@@ -35,6 +35,12 @@ public:
   /// When emitting fixits as code edits, apply all fixits from diagnostics
   /// without any filtering.
   bool FixitCodeForAllDiagnostics = false;
+
+  /// Suppress all warnings
+  bool SuppressWarnings = false;
+
+  /// Treat all warnings as errors
+  bool WarningsAsErrors = false;
 };
 
 }

include/swift/Option/Options.td

@@ -218,6 +218,15 @@ def solver_memory_threshold : Separate<["-"], "solver-memory-threshold">,
   Flags<[FrontendOption, HelpHidden, DoesNotAffectIncrementalBuild]>,
   HelpText<"Set the upper bound for memory consumption, in bytes, by the constraint solver">;   
 
+// Diagnostic control options
+def suppress_warnings : Flag<["-"], "suppress-warnings">,
+  Flags<[FrontendOption, DoesNotAffectIncrementalBuild]>,
+  HelpText<"Suppress all warnings">;
+
+def warnings_as_errors : Flag<["-"], "warnings-as-errors">,
+  Flags<[FrontendOption, DoesNotAffectIncrementalBuild]>,
+  HelpText<"Treat warnings as errors">;
+
 // Platform options.
 def enable_app_extension : Flag<["-"], "application-extension">,
   Flags<[FrontendOption, NoInteractiveOption]>,

lib/AST/DiagnosticEngine.cpp

@@ -528,7 +528,7 @@ DiagnosticState::Behavior DiagnosticState::determineBehavior(DiagID id) {
   //   3) If the user provided a behavior for this diagnostic's kind, follow
   //      that
   if (diagInfo.kind == DiagnosticKind::Warning) {
-    if (ignoreAllWarnings)
+    if (suppressWarnings)
       return set(Behavior::Ignore);
     if (warningsAsErrors)
       return set(Behavior::Error);

lib/Driver/Driver.cpp

@@ -147,6 +147,13 @@ static void validateArgs(DiagnosticEngine &diags, const ArgList &Args) {
       }
     }
   }
+
+  // Check for conflicting warning control flags
+  if (Args.hasArg(options::OPT_suppress_warnings) &&
+      Args.hasArg(options::OPT_warnings_as_errors)) {
+    diags.diagnose(SourceLoc(), diag::error_conflicting_options,
+                   "-warnings-as-errors", "-suppress-warnings");
+  }
 }
 
 static void computeArgsHash(SmallString<32> &out, const DerivedArgList &args) {

lib/Driver/ToolChains.cpp

@@ -126,8 +126,10 @@ static void addCommonFrontendArgs(const ToolChain &TC,
   inputArgs.AddLastArg(arguments, options::OPT_parse_stdlib);
   inputArgs.AddLastArg(arguments, options::OPT_resource_dir);
   inputArgs.AddLastArg(arguments, options::OPT_solver_memory_threshold);
+  inputArgs.AddLastArg(arguments, options::OPT_suppress_warnings);
   inputArgs.AddLastArg(arguments, options::OPT_profile_generate);
   inputArgs.AddLastArg(arguments, options::OPT_profile_coverage_mapping);
+  inputArgs.AddLastArg(arguments, options::OPT_warnings_as_errors);
 
   // Pass on any build config options
   inputArgs.AddAllArgs(arguments, options::OPT_D);

lib/Frontend/CompilerInvocation.cpp

@@ -922,6 +922,11 @@ static bool ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
     Args.hasArg(OPT_show_diagnostics_after_fatal);
   Opts.UseColor |= Args.hasArg(OPT_color_diagnostics);
   Opts.FixitCodeForAllDiagnostics |= Args.hasArg(OPT_fixit_all);
+  Opts.SuppressWarnings |= Args.hasArg(OPT_suppress_warnings);
+  Opts.WarningsAsErrors |= Args.hasArg(OPT_warnings_as_errors);
+
+  assert(!(Opts.WarningsAsErrors && Opts.SuppressWarnings) &&
+         "conflicting arguments; should of been caught by driver");
 
   return false;
 }

lib/Frontend/Frontend.cpp

@@ -69,6 +69,12 @@ bool CompilerInstance::setup(const CompilerInvocation &Invok) {
   if (Invocation.getDiagnosticOptions().ShowDiagnosticsAfterFatalError) {
     Diagnostics.setShowDiagnosticsAfterFatalError();
   }
+  if (Invocation.getDiagnosticOptions().SuppressWarnings) {
+    Diagnostics.setSuppressWarnings(true);
+  }
+  if (Invocation.getDiagnosticOptions().WarningsAsErrors) {
+    Diagnostics.setWarningsAsErrors(true);
+  }
 
   // If we are asked to emit a module documentation file, configure lexing and
   // parsing to remember comments.

test/Driver/warnings-control.swift

@@ -0,0 +1,24 @@
+// RUN: not %target-swiftc_driver %s 2>&1 | FileCheck -check-prefix=DEFAULT %s
+// RUN: not %target-swiftc_driver -warnings-as-errors %s 2>&1 | FileCheck -check-prefix=WERR %s
+// RUN: not %target-swiftc_driver -suppress-warnings %s 2>&1 | FileCheck -check-prefix=NOWARN %s
+
+// RUN: not %target-swiftc_driver -suppress-warnings -warnings-as-errors %s 2>&1 | FileCheck -check-prefix=FLAGS_CONFLICT %s
+// FLAGS_CONFLICT: error: conflicting options '-warnings-as-errors' and '-suppress-warnings'
+
+func foo() -> Int {
+	let x = 1
+	var y = 2 
+// DEFAULT:    warning: variable 'y' was never mutated; consider changing to 'let' constant 	
+// WERR:       error: variable 'y' was never mutated; consider changing to 'let' constant 	
+// NOWARN-NOT: variable 'y' was never mutated
+	return x + y
+}
+
+func bar() {
+	foo()
+// To help anchor the checks, have an error. Put it inside a later function, to help make sure it comes after
+	xyz
+// DEFAULT: error: use of unresolved identifier 'xyz'
+// WERR:    error: use of unresolved identifier 'xyz'
+// NOWARN:  error: use of unresolved identifier 'xyz'
+}