lld-link: Make /linkrepro: take a filename, not a directory.

[thakis]

Summary

This makes lld-link behave like ld.lld. I don't see a reason for
the two drivers to have different behavior here.

While here, also make lld-link add a version.txt to the tar, like
ld.lld does.

[ruiu]

LGTM

Thank you for doing this.

[hans]

Nice!

But is there no help text or user manual that needs to be updated?

[thakis]

In D67461#1667296, @hans wrote:

Nice!

But is there no help text or user manual that needs to be updated?

The help text is "Dump linker invocation and input files for debugging" which is noncommittal enough to not need changing :) Once this and D67456 are in I want to look at also supporting the env var for linkrepro like in the ELF port (and it should work even with /lldignoreenv set, since it doesn't affect the normal output) and port the recent ELF changes that change the help text to make it look less like a lld dev debug flag; I was thinking about changing the help text then.

[thakis]

I realized why the behavior was different: link.exe has a /linkrepro: flag that behaves like lld-link's used to (https://www.geoffchappell.com/studies/msvc/link/link/options/linkrepro.htm?tx=37). It also honors a link_repro env var.

So I think I'll have to revert this, and add a comment explaining why things are different.

[pcc]

In D67461#1675640, @thakis wrote:

I realized why the behavior was different: link.exe has a /linkrepro: flag that behaves like lld-link's used to (https://www.geoffchappell.com/studies/msvc/link/link/options/linkrepro.htm?tx=37). It also honors a link_repro env var.

Yes, that's why I originally made this take a directory instead of a file name.

So I think I'll have to revert this, and add a comment explaining why things are different.

I guess another option would be to rename this flag to /lldlinkrepro, which would let us implement link.exe-compatible behaviour under /linkrepro in the future.

[hans]

I just noticed that MS added docs for their /linkrepro flag: https://github.com/MicrosoftDocs/cpp-docs/commit/59aeb70085f4068c8b46642b87b89993b8d65699

lld/trunk/COFF/Driver.cpp

 #include "llvm/ToolDrivers/llvm-lib/LibDriver.h"
 #include <algorithm>
 #include <future>
 #include <memory>
 
 using namespace llvm;
 using namespace llvm::object;
 using namespace llvm::COFF;
-using llvm::sys::Process;
+using namespace llvm::sys;
 
 namespace lld {
 namespace coff {
 
 static Timer inputFileTimer("Input File Reading", Timer::root());
 
 Configuration *config;
 LinkerDriver *driver;
if (args.hasArg(OPT_dash_dash_version)) {
     return;
   }
 
   // Handle /lldmingw early, since it can potentially affect how other
   // options are handled.
   config->mingw = args.hasArg(OPT_lldmingw);
 
   if (auto *arg = args.getLastArg(OPT_linkrepro)) {
-    SmallString<64> path = StringRef(arg->getValue());
-    sys::path::append(path, "repro.tar");
+    const char *path = arg->getValue();
 
     Expected<std::unique_ptr<TarWriter>> errOrWriter =
-        TarWriter::create(path, "repro");
-
+        TarWriter::create(path, path::stem(path));
     if (errOrWriter) {
       tar = std::move(*errOrWriter);
+      tar->append("version.txt", getLLDVersion() + "\n");
     } else {
-      error("/linkrepro: failed to open " + path + ": " +
-            toString(errOrWriter.takeError()));
+      error("/linkrepro: " + toString(errOrWriter.takeError()));
     }
   }
 
   if (!args.hasArg(OPT_INPUT)) {
     if (args.hasArg(OPT_deffile))
       config->noEntry = true;
     else
       fatal("no input files");

lld/trunk/docs/ReleaseNotes.rst

 ELF Improvements
 ----------------
 
 * ...
 
 COFF Improvements
 -----------------
 
+* /linkrepro: now takes the filename of the tar archive it writes, instead
+  of the name of a directory that a file called "repro.tar" is created in,
+  matching the behavior of ELF lld.
 * ...
 
 MinGW Improvements
 ------------------
 
 * ...
 
 MachO Improvements

lld/trunk/test/COFF/linkrepro-res.test

 # REQUIRES: x86, shell
 
 # RUN: rm -rf %t.dir
 # RUN: mkdir -p %t.dir/build
 # RUN: cd %t.dir/build
 # RUN: lld-link %p/Inputs/resource.res /subsystem:console /machine:x64 \
-# RUN:   /entry:__ImageBase /linkrepro:. /out:%t.exe
+# RUN:   /entry:__ImageBase /linkrepro:repro.tar /out:%t.exe
 # RUN: tar xf repro.tar
 # RUN: diff %p/Inputs/resource.res repro/%:p/Inputs/resource.res
 # RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
 
 # RSP: resource.res

lld/trunk/test/COFF/linkrepro.test

 # REQUIRES: x86, shell
 
 # RUN: rm -rf %t.dir
 # RUN: mkdir -p %t.dir/build1 %t.dir/build2 %t.dir/build3
 # RUN: yaml2obj < %p/Inputs/hello32.yaml > %t.obj
 
 # RUN: cd %t.dir/build1
 # RUN: lld-link %t.obj %p/Inputs/std32.lib /subsystem:console \
-# RUN:   /entry:main@0 /linkrepro:. /out:%t.exe
+# RUN:   /entry:main@0 /linkrepro:repro.tar /out:%t.exe
 # RUN: tar xf repro.tar
 # RUN: diff %t.obj repro/%:t.obj
 # RUN: diff %p/Inputs/std32.lib repro/%:p/Inputs/std32.lib
 # RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
 
 # RUN: cd %t.dir/build2
 # RUN: lld-link %t.obj /libpath:%p/Inputs /defaultlib:std32 /subsystem:console \
-# RUN:   /entry:main@0 /linkrepro:. /out:%t.exe
+# RUN:   /entry:main@0 /linkrepro:repro.tar /out:%t.exe
 # RUN: tar xf repro.tar
 # RUN: diff %t.obj repro/%:t.obj
 # RUN: diff %p/Inputs/std32.lib repro/%:p/Inputs/std32.lib
 # RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
 
 # RUN: cd %t.dir/build3
 # RUN: env LIB=%p/Inputs lld-link %t.obj /defaultlib:std32 /subsystem:console \
-# RUN:   /entry:main@0 /linkrepro:. /out:%t.exe
+# RUN:   /entry:main@0 /linkrepro:repro.tar /out:%t.exe
 # RUN: tar xf repro.tar
 # RUN: diff %t.obj repro/%:t.obj
 # RUN: diff %p/Inputs/std32.lib repro/%:p/Inputs/std32.lib
 # RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
 
 # RSP: /subsystem:console
 # RSP: /entry:main@0
 # RSP-NOT: /linkrepro:
 # RSP: /out:
 # RSP: linkrepro.test.tmp.obj
 # RSP-NOT: defaultlib
 # RSP: std32.lib