[lld-macho] Don't warn on non-existent system libraries

[thakis]

Summary

Now, new mach-o lld no longer warns if the isysroot has just
usr/lib and System/Library/Frameworks but is missing usr/local/lib
and System/Frameworks.

This matches ld64 and old mach-o lld and fixes a regression from D85992.

It also fixes the only test failure in check-lld when running it
on an M1 Mac.

[thakis]

lld/test/MachO/syslibroot.test

31

This patch is also fixing this test ffailing on one of my macs, in a fairly normal setup (commandline tools installed, xcode not installed, m1).

[smeenai]

lld/test/MachO/syslibroot.test

31

I don't quite understand this. A final syslibroot of just / is supposed to ignore any previously specified roots (a hack which we inherit from ld64), and I believe that's what this test was for. I don't see how your code change affects this test?

[thakis]

lld/test/MachO/syslibroot.test

31

Without my patch, the output of the command under test is (on my linux box):

$ out/gn/bin/lld -flavor darwinnew -v -syslibroot /var/empty -syslibroot /
lld: warning: directory not found for option -F/Library/Frameworks
lld: warning: directory not found for option -F/System/Library/Frameworks
LLD 12.0.0
Library search paths:
	/usr/lib
	/usr/local/lib
Framework search paths:

After my change, it is just:

$ out/gn/bin/lld -flavor darwinnew -v -syslibroot /var/empty -syslibroot /
LLD 12.0.0
Library search paths:
	/usr/lib
	/usr/local/lib
Framework search paths:

Previously, the "/usr/local/lib" in the CHECK-SYSLIBROOT-IGNORED line matched against the "warning: directory not found" line, but now that the warning is gone the test fails instead. I don't know if it was supposed to match against that warning line (the "mach here is fuzzy" comment isn't quite clear to me), but after this change it can't match the warning line any longer.

[thakis]

lld/test/MachO/syslibroot.test

31

(Sorry, this output was for the other test further. But I'm guessing the test here currently passes on Windows for the same reason -- and it fails on my m1 mac because it has /usr/lib but not /usr/local/lib so it currently emits a warning for /usr/local/lib and then prints /usr/lib as search path, and that means /usr/local/lib and /usr/lib are not in the order the CHECK lines here currently expect. For the M1, this is indeed independent of my patch – the test fails at head, without the change.)

[int3]

@compnerd, want to have a look at this since you wrote the original test?

[compnerd]

lld/test/MachO/syslibroot.test

31

The match there was to prevent the accidental match. I think that we should retain the test, but remove the match against the warning. We should verify that we ignore the non-default-search paths here.

[thakis]

update test as discussed over chat

lld/MachO/Driver.cpp

getSearchPaths(unsigned optionCode, opt::InputArgList &args,
   // `-Z` suppresses the standard "system" search paths.
   if (args.hasArg(OPT_Z))
     return paths;
 
   for (auto const &path : systemPaths) {
     for (auto root : roots) {
       SmallString<261> buffer(root);
       path::append(buffer, path);
-      if (warnIfNotDirectory(optionLetter, buffer))
+      if (fs::is_directory(buffer))
         paths.push_back(saver.save(buffer.str()));
     }
   }
   return paths;
 }
 
 static std::vector<StringRef> getSystemLibraryRoots(opt::InputArgList &args) {
   std::vector<StringRef> roots;

lld/test/MachO/syslibroot.test

 # Ensure that a nonexistent path is ignored with a syslibroot
 
 RUN: lld -flavor darwinnew -v -syslibroot /var/empty | FileCheck %s -check-prefix CHECK-NONEXISTENT-SYSLIBROOT
 
 CHECK-NONEXISTENT-SYSLIBROOT: Library search paths:
 CHECK-NONEXISTENT-SYSLIBROOT-NEXT: Framework search paths:
 
 RUN: mkdir -p %t/usr/lib
-RUN: lld -flavor darwinnew -v -syslibroot %t | FileCheck %s -check-prefix CHECK-SYSLIBROOT -DROOT=%t
+RUN: lld -flavor darwinnew -v -syslibroot %t 2>&1 | FileCheck %s -check-prefix CHECK-SYSLIBROOT -DROOT=%t
 
+CHECK-SYSLIBROOT-NOT: directory not found{{.*}}usr/local/lib
 CHECK-SYSLIBROOT: Library search paths:
 CHECK-SYSLIBROOT-NEXT: [[ROOT]]/usr/lib
 
 RUN: mkdir -p %t/Library/libxml2-development
 RUN: lld -flavor darwinnew -v -syslibroot %t -L /Library/libxml2-development | FileCheck %s -check-prefix CHECK-ABSOLUTE-PATH-REROOTED -DROOT=%t
 
 CHECK-ABSOLUTE-PATH-REROOTED: Library search paths:
 CHECK-ABSOLUTE-PATH-REROOTED: [[ROOT]]/Library/libxml2-development
 CHECK-ABSOLUTE-PATH-REROOTED: [[ROOT]]/usr/lib
 
 RUN: lld -flavor darwinnew -v -syslibroot %t -L %t/Library/libxml2-development | FileCheck %s -check-prefix CHECK-PATH-WITHOUT-REROOT -DPATH=%t/Library/libxml2-development
 CHECK-PATH-WITHOUT-REROOT:      Library search paths:
 CHECK-PATH-WITHOUT-REROOT-NEXT: [[PATH]]
 
-# NOTE: the match here is fuzzy because the default search paths exist on Linux
-# and macOS, but not on Windows (that is we ignore `/var/empty`).  This allows
-# us to run the test uniformly on all the platforms.
-RUN: lld -flavor darwinnew -v -syslibroot /var/empty -syslibroot / 2>&1 | FileCheck %s -check-prefix CHECK-SYSLIBROOT-IGNORED
-
-CHECK-SYSLIBROOT-IGNORED: /usr/lib
-CHECK-SYSLIBROOT-IGNORED: /usr/local/lib
-
 RUN: mkdir -p %t.2/usr/lib
 RUN: lld -flavor darwinnew -v -syslibroot %t -syslibroot %t.2 | FileCheck %s -check-prefix CHECK-SYSLIBROOT-MATRIX -DROOT=%t
 
 CHECK-SYSLIBROOT-MATRIX: Library search paths:
 CHECK-SYSLIBROOT-MATRIX: [[ROOT]]/usr/lib
 CHECK-SYSLIBROOT-MATRIX: [[ROOT]].2/usr/lib
 
+RUN: lld -flavor darwinnew -v -syslibroot %t -syslibroot %t.2 -syslibroot / | FileCheck %s -check-prefix CHECK-SYSLIBROOT-IGNORED -DROOT=%t
+
+CHECK-SYSLIBROOT-IGNORED: Library search paths:
+CHECK-SYSLIBROOT-IGNORED-NOT: [[ROOT]]/usr/lib
+CHECK-SYSLIBROOT-IGNORED-NOT: [[ROOT]].2/usr/lib
+
 RUN: mkdir -p %t/System/Library/Frameworks
 RUN: lld -flavor darwinnew -v -syslibroot %t | FileCheck %s -check-prefix CHECK-SYSLIBROOT-FRAMEWORK -DROOT=%t
 
 CHECK-SYSLIBROOT-FRAMEWORK: Framework search paths:
 CHECK-SYSLIBROOT-FRAMEWORK: [[ROOT]]/System/Library/Frameworks
 
-# NOTE: the match here is fuzzy because the default search paths exist on Linux
-# and macOS, but not on Windows (that is we ignore `/var/empty`).  This allows
-# us to run the test uniformly on all the platforms.
-RUN: lld -flavor darwinnew -v -syslibroot /var/empty -syslibroot / 2>&1 | FileCheck %s -check-prefix CHECK-SYSLIBROOT-FRAMEWORK-IGNORED
-
-CHECK-SYSLIBROOT-FRAMEWORK-IGNORED: /System/Library/Framework
-
 RUN: mkdir -p %t/Library/Frameworks
 RUN: mkdir -p %t.2/Library/Frameworks
 RUN: lld -flavor darwinnew -v -syslibroot %t -syslibroot %t.2 -F /Library/Frameworks | FileCheck %s -check-prefix CHECK-SYSLIBROOT-FRAMEWORK-MATRIX -DROOT=%t
 
 CHECK-SYSLIBROOT-FRAMEWORK-MATRIX: Framework search paths:
 CHECK-SYSLIBROOT-FRAMEWORK-MATRIX: [[ROOT]]/Library/Frameworks
 CHECK-SYSLIBROOT-FRAMEWORK-MATRIX: [[ROOT]].2/Library/Frameworks
+
+RUN: lld -flavor darwinnew -v -syslibroot %t -syslibroot %t.2 -syslibroot / -F /Library/Frameworks | FileCheck %s -check-prefix CHECK-SYSLIBROOT-FRAMEWORK-IGNORED -DROOT=%t
+
+CHECK-SYSLIBROOT-FRAMEWORK-IGNORED: Framework search paths:
+CHECK-SYSLIBROOT-FRAMEWORK-IGNORED-NOT: [[ROOT]]/Library/Frameworks
+CHECK-SYSLIBROOT-FRAMEWORK-IGNORED-NOT: [[ROOT]].2/Library/Frameworks