[Driver] Use ld.lld directly for Fuchsia rather than passing flavor

[phosek]

Summary

Passing a flavor to LLD requires command line argument, but if these
are being passed through a response file, this will fail because LLD
needs to know which driver to use before processing the response file.
Use ld.lld directly instead to avoid this issue.

[mcgrathr]

This seems like how it always should have been, since -fuse-ld=lld sets it to ld.lld, not lld.
Looks to me like the existing MipsLinux and WebAssembly implementations are wrong too and only BareMetal is right.

cfe/trunk/lib/Driver/ToolChains/Fuchsia.h

AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;
   void
   AddClangCXXStdlibIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                                llvm::opt::ArgStringList &CC1Args) const override;
   void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
                            llvm::opt::ArgStringList &CmdArgs) const override;
 
   const char *getDefaultLinker() const override {
-    return "lld";
+    return "ld.lld";
   }
 
 protected:
   Tool *buildLinker() const override;
 };
 
 } // end namespace toolchains
 } // end namespace driver
 } // end namespace clang
 
 #endif // LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_FUCHSIA_H

cfe/trunk/lib/Driver/ToolChains/Fuchsia.cpp

void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   Args.ClaimAllArgs(options::OPT_g_Group);
   // and "clang -emit-llvm foo.o -o foo"
   Args.ClaimAllArgs(options::OPT_emit_llvm);
   // and for "clang -w foo.o -o foo". Other warning options are already
   // handled somewhere else.
   Args.ClaimAllArgs(options::OPT_w);
 
   const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
-  if (llvm::sys::path::stem(Exec).equals_lower("lld")) {
-    CmdArgs.push_back("-flavor");
-    CmdArgs.push_back("gnu");
-
+  if (llvm::sys::path::filename(Exec).equals_lower("ld.lld") ||
+      llvm::sys::path::stem(Exec).equals_lower("ld.lld")) {
     CmdArgs.push_back("-z");
     CmdArgs.push_back("rodynamic");
   }
 
   if (!D.SysRoot.empty())
     CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
 
   if (!Args.hasArg(options::OPT_shared) && !Args.hasArg(options::OPT_r))

cfe/trunk/test/Driver/fuchsia.c

 // RUN: %clang %s -### -no-canonical-prefixes --target=x86_64-unknown-fuchsia \
-// RUN:     --sysroot=%S/platform -fuse-ld=ld 2>&1 \
+// RUN:     --sysroot=%S/platform 2>&1 \
 // RUN:     | FileCheck -check-prefixes=CHECK,CHECK-X86_64 %s
 // RUN: %clang %s -### -no-canonical-prefixes --target=aarch64-unknown-fuchsia \
-// RUN:     --sysroot=%S/platform -fuse-ld=ld 2>&1 \
+// RUN:     --sysroot=%S/platform 2>&1 \
 // RUN:     | FileCheck -check-prefixes=CHECK,CHECK-AARCH64 %s
 // CHECK: {{.*}}clang{{.*}}" "-cc1"
 // CHECK: "-munwind-tables"
 // CHECK: "-fuse-init-array"
 // CHECK: "-isysroot" "[[SYSROOT:[^"]+]]"
 // CHECK: "-internal-externc-isystem" "[[SYSROOT]]{{/|\\\\}}include"
-// CHECK: {{.*}}lld{{.*}}" "-flavor" "gnu"
-// CHECK: "-z" "rodynamic"
+// CHECK: {{.*}}ld.lld{{.*}}" "-z" "rodynamic"
 // CHECK: "--sysroot=[[SYSROOT]]"
 // CHECK: "-pie"
 // CHECK: "--build-id"
 // CHECK: "--hash-style=gnu"
 // CHECK: "-dynamic-linker" "ld.so.1"
 // CHECK: Scrt1.o
 // CHECK-NOT: crti.o
 // CHECK-NOT: crtbegin.o

cfe/trunk/test/Driver/fuchsia.cpp

 // RUN: %clangxx %s -### -no-canonical-prefixes --target=x86_64-unknown-fuchsia \
-// RUN:     --sysroot=%S/platform 2>&1 -fuse-ld=ld | FileCheck %s
+// RUN:     --sysroot=%S/platform 2>&1 | FileCheck %s
 // CHECK: {{.*}}clang{{.*}}" "-cc1"
 // CHECK: "-triple" "x86_64-fuchsia"
 // CHECK: "-fuse-init-array"
 // CHECK: "-isysroot" "[[SYSROOT:[^"]+]]"
 // CHECK: "-internal-isystem" "{{.*[/\\]}}x86_64-fuchsia{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK: "-internal-externc-isystem" "[[SYSROOT]]{{/|\\\\}}include"
-// CHECK: {{.*}}lld{{.*}}" "-flavor" "gnu"
-// CHECK: "-z" "rodynamic"
+// CHECK: {{.*}}ld.lld{{.*}}" "-z" "rodynamic"
 // CHECK: "--sysroot=[[SYSROOT]]"
 // CHECK: "-pie"
 // CHECK: "--build-id"
 // CHECK: "-dynamic-linker" "ld.so.1"
 // CHECK: Scrt1.o
 // CHECK-NOT: crti.o
 // CHECK-NOT: crtbegin.o
 // CHECK: "-L[[SYSROOT]]{{/|\\\\}}lib"