Fix the frontend unit test behavior.

If -sycl-std is passed to the driver without -fsycl, then it is not
passed to the -cc1 invocation.

Author: AaronBallman

clang/include/clang/Driver/Options.td

@@ -4271,10 +4271,6 @@ def fsycl : Flag<["-"], "fsycl">, Flags<[NoXarchOption, CoreOption]>, Group<sycl
   HelpText<"Enables SYCL kernels compilation for device">;
 def fno_sycl : Flag<["-"], "fno-sycl">, Flags<[NoXarchOption, CoreOption]>, Group<sycl_Group>,
   HelpText<"Disables SYCL kernels compilation for device">;
-def sycl_std_EQ : Joined<["-"], "sycl-std=">, Group<sycl_Group>, Flags<[CC1Option, NoArgumentUnused, CoreOption]>,
-  HelpText<"SYCL language standard to compile for.">, Values<"2020,2017,121,1.2.1,sycl-1.2.1">,
-  NormalizedValues<["SYCL_2020", "SYCL_2017", "SYCL_2017", "SYCL_2017", "SYCL_2017"]>, NormalizedValuesScope<"LangOptions">,
-  MarshallingInfoString<LangOpts<"SYCLVersion">, "SYCL_None">, AutoNormalizeEnum;
 defm sycl_esimd: OptInFFlag<"sycl-explicit-simd", "Enable", "Disable", " SYCL explicit SIMD extension.", [CC1Option,CoreOption], LangOpts<"SYCLExplicitSIMD">>;
 defm sycl_early_optimizations : OptOutFFlag<"sycl-early-optimizations", "Enable", "Disable", " standard optimization pipeline for SYCL device compiler", [CoreOption]>;
 def fsycl_dead_args_optimization : Flag<["-"], "fsycl-dead-args-optimization">,
@@ -5486,6 +5482,11 @@ def fsycl_is_device : Flag<["-"], "fsycl-is-device">,
 def fsycl_is_host : Flag<["-"], "fsycl-is-host">,
   HelpText<"SYCL host compilation">,
   MarshallingInfoFlag<LangOpts<"SYCLIsHost">>;
+def sycl_std_EQ : Joined<["-"], "sycl-std=">, Group<sycl_Group>, Flags<[CC1Option, NoArgumentUnused, CoreOption]>,
+  HelpText<"SYCL language standard to compile for.">, Values<"2020,2017,121,1.2.1,sycl-1.2.1">,
+  NormalizedValues<["SYCL_2020", "SYCL_2017", "SYCL_2017", "SYCL_2017", "SYCL_2017"]>, NormalizedValuesScope<"LangOptions">,
+  MarshallingInfoString<LangOpts<"SYCLVersion">, "SYCL_None">,
+  ShouldParseIf<!strconcat(fsycl_is_device.KeyPath, "||", fsycl_is_host.KeyPath)>, AutoNormalizeEnum;
 def fsycl_int_header : Separate<["-"], "fsycl-int-header">,
   HelpText<"Generate SYCL integration header into this file.">,
   MarshallingInfoString<LangOpts<"SYCLIntHeader">>;

clang/unittests/Frontend/CompilerInvocationTest.cpp

@@ -559,12 +559,12 @@ TEST_F(CommandLineTest, ConditionalParsingIfTrueFlagPresent) {
   CompilerInvocation::CreateFromArgs(Invocation, Args, *Diags);
 
   ASSERT_TRUE(Diags->hasErrorOccurred());
-  ASSERT_EQ(Invocation.getLangOpts()->getSYCLVersion(), LangOptions::SYCL_2017);
+  ASSERT_EQ(Invocation.getLangOpts()->getSYCLVersion(), LangOptions::SYCL_None);
 
   Invocation.generateCC1CommandLine(GeneratedArgs, *this);
 
   ASSERT_THAT(GeneratedArgs, Not(Contains(StrEq("-fsycl"))));
-  ASSERT_THAT(GeneratedArgs, Contains(StrEq("-sycl-std=2017")));
+  ASSERT_THAT(GeneratedArgs, Not(Contains(StrEq("-sycl-std=2017"))));
 }
 
 // Wide integer option.