[Driver] Change -fnostack-clash-protection to -fno-stack-clash-protection

[xbolva00]

Summary

Clang command line docs mention -fno-stack-clash-protection, and GCC also uses -fno-stack-clash-protection.

Fixes PR47139

[tstellar]

LGTM. Thanks.

clang/include/clang/Driver/Options.td

 def fspell_checking_limit_EQ : Joined<["-"], "fspell-checking-limit=">, Group<f_Group>;
 def fsigned_bitfields : Flag<["-"], "fsigned-bitfields">, Group<f_Group>;
 defm signed_char : OptOutFFlag<"signed-char", "char is signed", "char is unsigned">;
 def fsplit_stack : Flag<["-"], "fsplit-stack">, Group<f_Group>;
 def fstack_protector_all : Flag<["-"], "fstack-protector-all">, Group<f_Group>,
   HelpText<"Enable stack protectors for all functions">;
 def fstack_clash_protection : Flag<["-"], "fstack-clash-protection">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Enable stack clash protection">;
-def fnostack_clash_protection : Flag<["-"], "fnostack-clash-protection">, Group<f_Group>,
+def fno_stack_clash_protection : Flag<["-"], "fno-stack-clash-protection">, Group<f_Group>,
   HelpText<"Disable stack clash protection">;
 def fstack_protector_strong : Flag<["-"], "fstack-protector-strong">, Group<f_Group>,
   HelpText<"Enable stack protectors for some functions vulnerable to stack smashing. "
            "Compared to -fstack-protector, this uses a stronger heuristic "
            "that includes functions containing arrays of any size (and any type), "
            "as well as any calls to alloca or the taking of an address from a local variable">;
 def fstack_protector : Flag<["-"], "fstack-protector">, Group<f_Group>,
   HelpText<"Enable stack protectors for some functions vulnerable to stack smashing. "

clang/lib/Driver/ToolChains/Clang.cpp

static void RenderSCPOptions(const ToolChain &TC, const ArgList &Args,
   if (!EffectiveTriple.isOSLinux())
     return;
 
   if (!EffectiveTriple.isX86() && !EffectiveTriple.isSystemZ() &&
       !EffectiveTriple.isPPC64())
     return;
 
   if (Args.hasFlag(options::OPT_fstack_clash_protection,
-                   options::OPT_fnostack_clash_protection, false))
+                   options::OPT_fno_stack_clash_protection, false))
     CmdArgs.push_back("-fstack-clash-protection");
 }
 
 static void RenderTrivialAutoVarInitOptions(const Driver &D,
                                             const ToolChain &TC,
                                             const ArgList &Args,
                                             ArgStringList &CmdArgs) {
   auto DefaultTrivialAutoVarInit = TC.GetDefaultTrivialAutoVarInit();

clang/test/Driver/stack-clash-protection.c

 // RUN: %clang -target i386-unknown-linux -fstack-clash-protection -### %s 2>&1 | FileCheck %s -check-prefix=SCP-i386
-// RUN: %clang -target i386-unknown-linux -fnostack-clash-protection -fstack-clash-protection -### %s 2>&1 | FileCheck %s -check-prefix=SCP-i386
-// RUN: %clang -target i386-unknown-linux -fstack-clash-protection -fnostack-clash-protection -### %s 2>&1 | FileCheck %s -check-prefix=SCP-i386-NO
+// RUN: %clang -target i386-unknown-linux -fno-stack-clash-protection -fstack-clash-protection -### %s 2>&1 | FileCheck %s -check-prefix=SCP-i386
+// RUN: %clang -target i386-unknown-linux -fstack-clash-protection -fno-stack-clash-protection -### %s 2>&1 | FileCheck %s -check-prefix=SCP-i386-NO
 // SCP-i386: "-fstack-clash-protection"
 // SCP-i386-NO-NOT: "-fstack-clash-protection"
 
 // RUN: %clang -target x86_64-scei-linux -fstack-clash-protection -### %s 2>&1 | FileCheck %s -check-prefix=SCP-x86
 // SCP-x86: "-fstack-clash-protection"
 
 // RUN: %clang -target armv7k-apple-linux -fstack-clash-protection -### %s 2>&1 | FileCheck %s -check-prefix=SCP-armv7
 // SCP-armv7-NOT: "-fstack-clash-protection"