[lld-link] Add support for /ignore:4037.

[thakis]

Summary

Fixes PR36657.

[hans]

COFF/Driver.cpp

809

Higher-level question: link.exe prints the warning number here, so the user can figure out what /ignore option to pass. Is there some way we can let an lld-link.exe user figure out how to ignore this warning?

[thakis]

COFF/Driver.cpp

809

This is imho an excellent question, and I wondered about this myself. /ignore:4217 (already implemented) has the same problem – so since this is consistent with that warning, I figured I don't need to figure this out right now.

lld-link's warning configurability is generally nonexistent, making this even less obvious. Maybe we should add "[/ignore:N to ignore]" to the end of the warning text for warnings that have a disable flag? That seems like a good approach to me – Rui, what do you think? But that should be a separate patch.

[hans]

COFF/Driver.cpp

809

Yes, absolutely this should be handled separately, just wanted to raise the question.

Your patch looks good to me

[thakis]

r327124, thanks!

[aganea]

Side note - I raised the /ignore issue here: https://bugs.llvm.org/show_bug.cgi?id=36445

In the future I think this should be fixed once for all by tagging the messages with the corresponding Microsoft LNK number.

In that case, warn("/order...") could become lnkWarn(4217, "/order...") and automatically handle /ignore.

[ruiu]

In the future I think this should be fixed once for all by tagging the messages with the corresponding Microsoft LNK number.

In that case, warn("/order...") could become lnkWarn(4217, "/order...") and automatically handle /ignore.

Adding a helper function that takes an error number might make sense, but I think that the use of the function is fairly limited, because lld doesn't try to do the exact same thing as MSVC link.exe. We sometimes emit a warning on which MSVC would emit a warning, but that's not too many.

COFF/Config.h

struct Configuration {
   bool AllowBind = true;
   bool NxCompat = true;
   bool AllowIsolation = true;
   bool TerminalServerAware = true;
   bool LargeAddressAware = false;
   bool HighEntropyVA = false;
   bool AppContainer = false;
   bool MinGW = false;
+  bool WarnMissingOrderSymbol = true;
   bool WarnLocallyDefinedImported = true;
   bool Incremental = true;
 };
 
 extern Configuration *Config;
 
 } // namespace coff
 } // namespace lld
 
 #endif

COFF/Driver.cpp

static void parseOrderFile(StringRef Arg) {
   // Parse a file. An order file contains one symbol per line.
   // All symbols that were not present in a given order file are
   // considered to have the lowest priority 0 and are placed at
   // end of an output section.
   for (std::string S : args::getLines(MB->getMemBufferRef())) {
     if (Config->Machine == I386 && !isDecorated(S))
       S = "_" + S;
 
-    if (Set.count(S) == 0)
+    if (Set.count(S) == 0) {
+      if (Config->WarnMissingOrderSymbol)
         warn("/order:" + Arg + ": missing symbol: " + S);
+    }
     else
       Config->Order[S] = INT_MIN + Config->Order.size();
   }
 }
 
 void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   // If the first command line argument is "/lib", link.exe acts like lib.exe.
   // We call our own implementation of lib.exe that understands bitcode files.
void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   // Construct search path list.
   SearchPaths.push_back("");
   for (auto *Arg : Args.filtered(OPT_libpath))
     SearchPaths.push_back(Arg->getValue());
   addLibSearchPaths();
 
   // Handle /ignore
   for (auto *Arg : Args.filtered(OPT_ignore)) {
-    if (StringRef(Arg->getValue()) == "4217")
+    if (StringRef(Arg->getValue()) == "4037")
+      Config->WarnMissingOrderSymbol = false;
+    else if (StringRef(Arg->getValue()) == "4217")
       Config->WarnLocallyDefinedImported = false;
     // Other warning numbers are ignored.
   }
 
   // Handle /out
   if (auto *Arg = Args.getLastArg(OPT_out))
     Config->OutputFile = Arg->getValue();
 

test/COFF/order.test

 # CHECK: fn1
 # CHECK: fn2
 # CHECK: fn3
 # CHECK: fn4
 # CHECK: unrelated1
 # CHECK: unrelated2
 
 # RUN: lld-link -entry:fn1 -subsystem:console -opt:noref -debug %t1.obj %t2.obj \
-# RUN:   -lldmap:- -out:%t.exe | FileCheck -check-prefix=DEFAULT %s
+# RUN:   -lldmap:- -ignore:4037 -out:%t.exe | FileCheck -check-prefix=DEFAULT %s
 # DEFAULT: fn2
 # DEFAULT: fn3
 # DEFAULT: unrelated1
 # DEFAULT: unrelated2
 # DEFAULT: fn4
 # DEFAULT: fn1
 
 # RUN: echo fn1 > %t2.order
 # RUN: echo fn2 >> %t2.order
 # RUN: echo fn3 >> %t2.order
 # RUN: echo fn4 >> %t2.order
 # RUN: echo foo >> %t2.order
 # RUN: lld-link -entry:fn1 -subsystem:console -debug %t1.obj %t2.obj \
 # RUN:   -out:%t.exe -order:@%t2.order 2>&1 | FileCheck -check-prefix=WARN %s
 # WARN: warning: /order:{{.*}} missing symbol: foo
 # WARN-NOT: f2
 # WARN-NOT: f3
 # WARN-NOT: f4
+# RUN: lld-link -entry:fn1 -subsystem:console -debug %t1.obj %t2.obj \
+# RUN:   -out:%t.exe -order:@%t2.order -ignore:4037 2>&1 | \
+# RUN:   FileCheck -allow-empty -check-prefix=NOWARN %s
+# NOWARN-NOT: warning: /order:{{.*}} missing symbol: foo
+# NOWARN-NOT: f2
+# NOWARN-NOT: f3
+# NOWARN-NOT: f4
 
 --- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64
   Characteristics: [  ]
 sections:
   - Name:            .text
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]