[clang] 64da6eb - [Driver][Gnu] -r: imply -nostdlib like GCC

[Fangrui Song via cfe-commits]

Author: Fangrui Song
Date: 2022-01-13T11:25:23-08:00
New Revision: 64da6eb06570adf38c96075de0116f6d29d5ba81

URL: https://github.com/llvm/llvm-project/commit/64da6eb06570adf38c96075de0116f6d29d5ba81
DIFF: https://github.com/llvm/llvm-project/commit/64da6eb06570adf38c96075de0116f6d29d5ba81.diff

LOG: [Driver][Gnu] -r: imply -nostdlib like GCC

See `gcc -dumpspecs` that -r essentially implies -nostdlib and suppresses
default -l* and crt*.o. The behavior makes sense because otherwise there will be
assuredly conflicting definitions when the relocatable output is linked into the
final executable/shared object.

Reviewed By: thesamesam, phosek

Differential Revision: https://reviews.llvm.org/D116843

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/Gnu.cpp
    clang/test/Driver/linux-cross.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index 7aeadd84dfee8..fbb1af4dbe22b 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -487,7 +487,8 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());
 
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles)) {
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles,
+                   options::OPT_r)) {
     if (!isAndroid && !IsIAMCU) {
       const char *crt1 = nullptr;
       if (!Args.hasArg(options::OPT_shared)) {
@@ -563,7 +564,8 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   getToolChain().addProfileRTLibs(Args, CmdArgs);
 
   if (D.CCCIsCXX() &&
-      !Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
+      !Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs,
+                   options::OPT_r)) {
     if (ToolChain.ShouldLinkCXXStdlib(Args)) {
       bool OnlyLibstdcxxStatic = Args.hasArg(options::OPT_static_libstdcxx) &&
                                  !Args.hasArg(options::OPT_static);
@@ -578,7 +580,7 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   // Silence warnings when linking C code with a C++ '-stdlib' argument.
   Args.ClaimAllArgs(options::OPT_stdlib_EQ);
 
-  if (!Args.hasArg(options::OPT_nostdlib)) {
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_r)) {
     if (!Args.hasArg(options::OPT_nodefaultlibs)) {
       if (IsStatic || IsStaticPIE)
         CmdArgs.push_back("--start-group");

diff  --git a/clang/test/Driver/linux-cross.cpp b/clang/test/Driver/linux-cross.cpp
index 98e4b7cb1baa8..20d069112acf2 100644
--- a/clang/test/Driver/linux-cross.cpp
+++ b/clang/test/Driver/linux-cross.cpp
@@ -210,3 +210,14 @@
 // RUN: %clang -### %s --target=i686-linux-musl -mx32 --sysroot= \
 // RUN:   --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=MUSL_X32
 // MUSL_X32: "-dynamic-linker" "/lib/ld-musl-x32.so.1"
+
+/// -r suppresses default -l and crt*.o like -nostdlib.
+// RUN: %clang -### %s --target=x86_64-linux-gnu --sysroot=%S/Inputs/debian_multiarch_tree \
+// RUN:   -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin -resource-dir=%S/Inputs/resource_dir \
+// RUN:   --stdlib=platform --rtlib=platform -r 2>&1 | FileCheck %s --check-prefix=RELOCATABLE
+// RELOCATABLE:      "-internal-isystem"
+// RELOCATABLE-SAME: {{^}} "[[SYSROOT:[^"]+]]/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10"
+// RELOCATABLE:      "-L
+// RELOCATABLE-SAME: {{^}}[[SYSROOT]]/usr/lib/gcc/x86_64-linux-gnu/10"
+// RELOCATABLE-NOT:  "-l
+// RELOCATABLE-NOT:  crt{{[^.]+}}.o