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

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

Fixes PR47139

Reviewed By: tstellar

Differential Revision: https://reviews.llvm.org/D85844

(cherry picked from commit df3bfaa)

Author: davidbolvansky

clang/include/clang/Driver/Options.td

@@ -1780,7 +1780,7 @@ 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. "

clang/lib/Driver/ToolChains/Clang.cpp

@@ -2971,7 +2971,7 @@ static void RenderSCPOptions(const ToolChain &TC, const ArgList &Args,
     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");
 }
 

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

@@ -1,6 +1,6 @@
 // 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"