Don't warn if a symbol is assigned to the same version twice, but error if it is assigned to multiple

[• espindola]

Summary

It looks like the problem described in

https://reviews.llvm.org/D21555

Is that we would error if a symbol was assigned to the same version twice. It looks like we can avoid the warning in that case and actually error if a symbol is placed in conflicting versions.

This fixes pr28342.

[• espindola]

Rebased.

[davide]

LGTM, thanks Rafael.

[• espindola]

r326813

ELF/SymbolTable.cpp

void SymbolTable::assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
   // Assign the version.
   for (Symbol *Sym : Syms) {
     // Skip symbols containing version info because symbol versions
     // specified by symbol names take precedence over version scripts.
     // See parseSymbolVersion().
     if (Sym->getName().contains('@'))
       continue;
 
-    if (Sym->VersionId != Config->DefaultSymbolVersion)
-      warn("duplicate symbol '" + Ver.Name + "' in version script");
+    if (Sym->VersionId != Config->DefaultSymbolVersion &&
+        Sym->VersionId != VersionId)
+      error("duplicate symbol '" + Ver.Name + "' in version script");
     Sym->VersionId = VersionId;
   }
 }
 
 void SymbolTable::assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId) {
   if (!Ver.HasWildcard)
     return;
 

test/ELF/version-script.s

 # RUN: echo "{ global: foo1; local: *; };" > %t5.script
 # RUN: echo "VERSION_2.0 { global: foo3; local: *; };" >> %t5.script
 # RUN: not ld.lld --version-script %t5.script -shared %t.o %t2.so -o %t5.so 2>&1 | \
 # RUN:   FileCheck -check-prefix=ERR2 %s
 # ERR2: EOF expected, but got VERSION_2.0
 
 # RUN: echo "VERSION_1.0 { global: foo1; local: *; };" > %t6.script
 # RUN: echo "VERSION_2.0 { global: foo1; local: *; };" >> %t6.script
-# RUN: ld.lld --version-script %t6.script -shared %t.o %t2.so -o %t6.so 2>&1 | \
-# RUN:   FileCheck -check-prefix=WARN2 %s
-# WARN2: duplicate symbol 'foo1' in version script
+# RUN: not ld.lld --version-script %t6.script -shared %t.o %t2.so -o %t6.so 2>&1 | \
+# RUN:   FileCheck -check-prefix=ERR3 %s
+# ERR3: duplicate symbol 'foo1' in version script
 
 # RUN: echo "{ foo1; foo2; };" > %t.list
 # RUN: ld.lld --version-script %t.script --dynamic-list %t.list %t.o %t2.so -o %t2
 # RUN: llvm-readobj %t2 > /dev/null
 
 ## Check that we can handle multiple "--version-script" options.
 # RUN: echo "VERSION_1.0 { global : foo1; local : *; };" > %t7a.script
 # RUN: echo "VERSION_2.0 { global: foo3; local: *; };" > %t7b.script

 # ALL-NEXT:    Size: 0
 # ALL-NEXT:    Binding: Global
 # ALL-NEXT:    Type: None
 # ALL-NEXT:    Other: 0
 # ALL-NEXT:    Section: .text
 # ALL-NEXT:  }
 # ALL-NEXT: ]
 
+# RUN: echo "VERSION_1.0 { global: foo1; foo1; local: *; };" > %t8.script
+# RUN: ld.lld --version-script %t8.script -shared %t.o -o %t8.so --fatal-warnings
+
 .globl foo1
 foo1:
   call bar@PLT
   ret
 
 .globl foo2
 foo2:
   ret