[lld-macho] exported symbols can also be lazy

[gkm]

Summary

Literal (vs. patterns) exported symbols must be defined. Also accept LazySymbol alongside Defined.

[gkm]

• update test case

[int3]

Just to confirm -- does ld64 also not fetch a symbol from an archive even when it is specified as an -exported_symbol?

[gkm]

In D102099#2745731, @int3 wrote:

Just to confirm -- does ld64 also not fetch a symbol from an archive even when it is specified as an -exported_symbol?

You are correct. It does.
This diff is rubbish. I will abandon and resubmit a proper one. 😊

lld/MachO/Driver.cpp

for (const Symbol *undefined : config->explicitUndefineds) {
         return false;
       }
     }
     // Literal exported-symbol names must be defined, but glob
     // patterns need not match.
     for (const CachedHashStringRef &cachedName :
          config->exportedSymbols.literals) {
       if (const Symbol *sym = symtab->find(cachedName))
-        if (isa<Defined>(sym))
+        if (isa<Defined>(sym) || isa<LazySymbol>(sym))
           continue;
       error("undefined symbol " + cachedName.val() +
             "\n>>> referenced from option -exported_symbol(s_list)");
     }
 
     createSyntheticSections();
     createSyntheticSymbols();
 

lld/test/MachO/export-options.s

 # REQUIRES: x86
 
 # RUN: split-file %s %t
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos %t/default.s -o %t/default.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos %t/lazydef.s -o %t/lazydef.o
+# RUN: llvm-ar --format=darwin rcs %t/lazydef.a %t/lazydef.o
 
 ## Check that mixing exported and unexported symbol options yields an error
 # RUN: not %lld -dylib %t/default.o -o /dev/null \
 # RUN:         -exported_symbol a -unexported_symbol b 2>&1 | \
 # RUN:     FileCheck --check-prefix=CONFLICT %s
 
 # CONFLICT: error: cannot use both -exported_symbol* and -unexported_symbol* options
 # CONFLICT-NEXT: >>> ignoring unexports
 
-## Check that exported literal symbol name is present in symbol table
-# RUN: not %lld -dylib %t/default.o -o /dev/null \
-# RUN:         -exported_symbol absent_literal \
-# RUN:         -exported_symbol absent_gl?b 2>&1 | \
+## Check that exported literal Defined and LazySymbol names are present in symbol table
+# RUN: not %lld -dylib %t/default.o %t/lazydef.a -o /dev/null \
+# RUN:         -exported_symbol _present_lazy \
+# RUN:         -exported_symbol _absent_literal \
+# RUN:         -exported_symbol _absent_gl?b 2>&1 | \
 # RUN:     FileCheck --check-prefix=UNDEF %s
 
-# UNDEF: error: undefined symbol absent_literal
+# UNDEF: error: undefined symbol _absent_literal
 # UNDEF-NEXT: >>> referenced from option -exported_symbol(s_list)
-# UNDEF-NOT: error: {{.*}} absent_gl{{.}}b
+# UNDEF-NOT: error: undefined symbol _present_lazy
+# UNDEF-NOT: error: {{.*}} _absent_gl{{.}}b
 
 ## Check that exported symbol is global
 # RUN: not %lld -dylib %t/default.o -o /dev/null \
 # RUN:         -exported_symbol _private_extern 2>&1 | \
 # RUN:     FileCheck --check-prefix=PRIVATE %s
 
 # PRIVATE: error: cannot export hidden symbol _private_extern
 
 #--- default.s
 
 .globl _keep_globl, _hide_globl
 _keep_globl:
   retq
 _hide_globl:
   retq
 .private_extern _private_extern
 _private_extern:
   retq
 _private:
   retq
 
+#--- lazydef.s
+
+.globl _present_lazy
+_present_lazy:
+  retq
+
 ## Check that the export trie is unaltered
 # RUN: %lld -dylib %t/default.o -o %t/default
 # RUN: llvm-objdump --macho --exports-trie %t/default | \
 # RUN:     FileCheck --check-prefix=DEFAULT %s
 
 # DEFAULT-LABEL: Exports trie:
 # DEFAULT-DAG:   _hide_globl
 # DEFAULT-DAG:   _keep_globl