[Driver] Always use -z rodynamic for Fuchsia

[phosek]

Summary

Fuchsia uses read-only .dynamic section.

[mcgrathr]

Looks almost right. Might be overkill to add a test case that -z rodynamic is omitted with -fuse-ld=gold or something.

lib/Driver/ToolChains/Fuchsia.cpp

51

Should be inside the lld conditional, since only lld groks -z rodynamic.

[mcgrathr]

LGTM

lib/Driver/ToolChains/Fuchsia.cpp

void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   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");
   }
 
+  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))
     CmdArgs.push_back("-pie");
 
   if (Args.hasArg(options::OPT_rdynamic))
     CmdArgs.push_back("-export-dynamic");

test/Driver/fuchsia.c

 // RUN: %clang %s -### -no-canonical-prefixes --target=x86_64-unknown-fuchsia \
 // RUN:     --sysroot=%S/platform -fuse-ld=ld 2>&1 | FileCheck %s
 // CHECK: {{.*}}clang{{.*}}" "-cc1"
 // CHECK: "-fuse-init-array"
 // CHECK: "-isysroot" "[[SYSROOT:[^"]+]]"
 // CHECK: "-internal-externc-isystem" "[[SYSROOT]]{{/|\\\\}}include"
 // CHECK: {{.*}}lld{{.*}}" "-flavor" "gnu"
+// CHECK: "-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"

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
 // 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: "--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"