[ELF] - Do not error out when version declaration not found when building executable.

When building executable usually version script is absent.
Before this patch error was shown in the case when
symbol name contained version and there was no script to match it.
  Instead of error out patch allows
to create new version declaration in this case and use it.
gnu linkers do the same.

That is PR28359.

Differential revision: http://reviews.llvm.org/D21890

llvm-svn: 274828

lld/ELF/Config.h

@@ -84,6 +84,7 @@ struct Configuration {
   bool FatalWarnings;
   bool GcSections;
   bool GnuHash = false;
+  bool HasVersionScript = false;
   bool ICF;
   bool Mips64EL = false;
   bool NoGnuUnique;

lld/ELF/Driver.cpp

@@ -439,6 +439,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
     Config->DynamicList.push_back(Arg->getValue());
 
   if (auto *Arg = Args.getLastArg(OPT_version_script)) {
+    Config->HasVersionScript = true;
     if (Optional<MemoryBufferRef> Buffer = readFile(Arg->getValue()))
       parseVersionScript(*Buffer);
   }

lld/ELF/SymbolTable.cpp

@@ -186,6 +186,16 @@ static uint16_t getVersionId(Symbol *Sym, StringRef Name) {
       return Default ? I : (I | VERSYM_HIDDEN);
     ++I;
   }
+
+  // If we are not building shared and version script
+  // is not specified, then it is not a error, it is
+  // in common not to use script for linking executables.
+  // In this case we just create new version.
+  if (!Config->Shared && !Config->HasVersionScript) {
+    Config->SymbolVersions.push_back(elf::Version(Version));
+    return Default ? I : (I | VERSYM_HIDDEN);
+  }
+
   error("symbol " + Name + " has undefined version " + Version);
   return 0;
 }

lld/test/ELF/verdef-executable.s

@@ -0,0 +1,269 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1
+# RUN: ld.lld %t1 -o %t
+# RUN: llvm-readobj -t -V -dyn-symbols %t | FileCheck --check-prefix=EXE %s
+
+# EXE:      Symbols [
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name:
+# EXE-NEXT:      Value: 0x0
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Local
+# EXE-NEXT:      Type: None (0x0)
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: Undefined (0x0)
+# EXE-NEXT:    }
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name: _start
+# EXE-NEXT:      Value: 0x11004
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Global
+# EXE-NEXT:      Type: None
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: .text
+# EXE-NEXT:    }
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name: a
+# EXE-NEXT:      Value: 0x11000
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Global
+# EXE-NEXT:      Type: Function
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: .text
+# EXE-NEXT:    }
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name: b
+# EXE-NEXT:      Value: 0x11002
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Global
+# EXE-NEXT:      Type: Function
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: .text
+# EXE-NEXT:    }
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name: b
+# EXE-NEXT:      Value: 0x11001
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Global
+# EXE-NEXT:      Type: Function
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: .text
+# EXE-NEXT:    }
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name: b_1
+# EXE-NEXT:      Value: 0x11001
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Global
+# EXE-NEXT:      Type: Function
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: .text
+# EXE-NEXT:    }
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name: b_2
+# EXE-NEXT:      Value: 0x11002
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Global
+# EXE-NEXT:      Type: Function
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: .text
+# EXE-NEXT:    }
+# EXE-NEXT:    Symbol {
+# EXE-NEXT:      Name: c
+# EXE-NEXT:      Value: 0x11003
+# EXE-NEXT:      Size: 0
+# EXE-NEXT:      Binding: Global
+# EXE-NEXT:      Type: Function
+# EXE-NEXT:      Other: 0
+# EXE-NEXT:      Section: .text
+# EXE-NEXT:    }
+# EXE-NEXT:  ]
+# EXE-NEXT: DynamicSymbols [
+# EXE-NEXT: ]
+# EXE-NEXT: Version symbols {
+# EXE-NEXT: }
+# EXE-NEXT: SHT_GNU_verdef {
+# EXE-NEXT: }
+# EXE-NEXT: SHT_GNU_verneed {
+# EXE-NEXT: }
+
+# RUN: ld.lld -pie --export-dynamic %t1 -o %t2
+# RUN: llvm-readobj -t -V -dyn-symbols %t2 | \
+# RUN:   FileCheck --check-prefix=EXEDYN %s
+
+# EXEDYN:      DynamicSymbols [
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: @
+# EXEDYN-NEXT:      Value: 0x0
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Local
+# EXEDYN-NEXT:      Type: None
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: Undefined
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: _start@
+# EXEDYN-NEXT:      Value: 0x1004
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Global
+# EXEDYN-NEXT:      Type: None
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: .text
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: a@
+# EXEDYN-NEXT:      Value: 0x1000
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Global
+# EXEDYN-NEXT:      Type: Function
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: .text
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: b@@LIBSAMPLE_2.0
+# EXEDYN-NEXT:      Value: 0x1002
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Global
+# EXEDYN-NEXT:      Type: Function
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: .text
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: b@LIBSAMPLE_1.0
+# EXEDYN-NEXT:      Value: 0x1001
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Global
+# EXEDYN-NEXT:      Type: Function
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: .text
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: b_1@
+# EXEDYN-NEXT:      Value: 0x1001
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Global
+# EXEDYN-NEXT:      Type: Function
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: .text
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: b_2@
+# EXEDYN-NEXT:      Value: 0x1002
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Global
+# EXEDYN-NEXT:      Type: Function
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: .text
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Symbol {
+# EXEDYN-NEXT:      Name: c@
+# EXEDYN-NEXT:      Value: 0x1003
+# EXEDYN-NEXT:      Size: 0
+# EXEDYN-NEXT:      Binding: Global
+# EXEDYN-NEXT:      Type: Function
+# EXEDYN-NEXT:      Other: 0
+# EXEDYN-NEXT:      Section: .text
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:  ]
+# EXEDYN-NEXT:  Version symbols {
+# EXEDYN-NEXT:    Section Name: .gnu.version
+# EXEDYN-NEXT:    Address: 0x288
+# EXEDYN-NEXT:    Offset: 0x288
+# EXEDYN-NEXT:    Link: 1
+# EXEDYN-NEXT:    Symbols [
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 0
+# EXEDYN-NEXT:        Name: @
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 1
+# EXEDYN-NEXT:        Name: _start@
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 1
+# EXEDYN-NEXT:        Name: a@
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 2
+# EXEDYN-NEXT:        Name: b@@LIBSAMPLE_2.0
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 3
+# EXEDYN-NEXT:        Name: b@LIBSAMPLE_1.0
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 1
+# EXEDYN-NEXT:        Name: b_1@
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 1
+# EXEDYN-NEXT:        Name: b_2@
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:      Symbol {
+# EXEDYN-NEXT:        Version: 1
+# EXEDYN-NEXT:        Name: c@
+# EXEDYN-NEXT:      }
+# EXEDYN-NEXT:    ]
+# EXEDYN-NEXT:  }
+# EXEDYN-NEXT:  SHT_GNU_verdef {
+# EXEDYN-NEXT:    Definition {
+# EXEDYN-NEXT:      Version: 1
+# EXEDYN-NEXT:      Flags: Base
+# EXEDYN-NEXT:      Index: 1
+# EXEDYN-NEXT:      Hash:
+# EXEDYN-NEXT:      Name:
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Definition {
+# EXEDYN-NEXT:      Version: 1
+# EXEDYN-NEXT:      Flags: 0x0
+# EXEDYN-NEXT:      Index: 2
+# EXEDYN-NEXT:      Hash: 98456416
+# EXEDYN-NEXT:      Name: LIBSAMPLE_2.0
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:    Definition {
+# EXEDYN-NEXT:      Version: 1
+# EXEDYN-NEXT:      Flags: 0x0
+# EXEDYN-NEXT:      Index: 3
+# EXEDYN-NEXT:      Hash: 98457184
+# EXEDYN-NEXT:      Name: LIBSAMPLE_1.0
+# EXEDYN-NEXT:    }
+# EXEDYN-NEXT:  }
+# EXEDYN-NEXT:  SHT_GNU_verneed {
+# EXEDYN-NEXT:  }
+
+## Check when linking executable that error produced if version script
+## was specified and there are symbols with version in name that
+## is absent in script.
+# RUN: echo    "VERSION { \
+# RUN:          global: foo;   \
+# RUN:          local: *; }; " > %t.script
+# RUN: not ld.lld --version-script %t.script %t1 -o %t3 2>&1 | \
+# RUN:   FileCheck -check-prefix=ERR %s
+# ERR: symbol b@LIBSAMPLE_1.0 has undefined version LIBSAMPLE_1.0
+
+b@LIBSAMPLE_1.0 = b_1
+b@@LIBSAMPLE_2.0 = b_2
+
+.globl a
+.type  a,@function
+a:
+retq
+
+.globl b_1
+.type  b_1,@function
+b_1:
+retq
+
+.globl b_2
+.type  b_2,@function
+b_2:
+retq
+
+.globl c
+.type  c,@function
+c:
+retq
+
+.globl _start
+_start:
+ nop