[ELF] - Implement extern "c++" version script tag

Patch implements 'extern' version script tag.
Currently only values in quotes(") are supported.

Matching of externs is performed in the same pass as exact match of globals.

Differential revision: http://reviews.llvm.org/D21930

llvm-svn: 275257

1 files changed, 22 insertions, 4 deletions

diff --git a/lld/ELF/SymbolListFile.cpp b/lld/ELF/SymbolListFile.cpp
index 68867cf8ae6..1525540e259 100644
--- a/lld/ELF/SymbolListFile.cpp
+++ b/lld/ELF/SymbolListFile.cpp
@@ -77,6 +77,7 @@ public:
   void run();
 
 private:
+  void parseExtern(std::vector<SymbolVersion> *Globals);
   void parseVersion(StringRef Version);
   void parseLocal();
   void parseVersionSymbols(StringRef Version);
@@ -120,21 +121,38 @@ void VersionScriptParser::parseLocal() {
   Config->VersionScriptGlobalByDefault = false;
 }
 
+void VersionScriptParser::parseExtern(std::vector<SymbolVersion> *Globals) {
+  expect("extern");
+  expect("C++");
+  expect("{");
+
+  for (;;) {
+    if (peek() == "}" || Error)
+      break;
+    Globals->push_back({next(), true});
+    expect(";");
+  }
+
+  expect("}");
+  expect(";");
+}
+
 void VersionScriptParser::parseVersionSymbols(StringRef Version) {
-  std::vector<StringRef> *Globals;
+  std::vector<SymbolVersion> *Globals;
   if (Version.empty())
     Globals = &Config->VersionScriptGlobals;
   else
     Globals = &Config->SymbolVersions.back().Globals;
 
   for (;;) {
+    if (peek() == "extern")
+      parseExtern(Globals);
+
     StringRef Cur = peek();
-    if (Cur == "extern")
-      setError("extern keyword is not supported");
     if (Cur == "}" || Cur == "local:" || Error)
       return;
     next();
-    Globals->push_back(Cur);
+    Globals->push_back({Cur, false});
     expect(";");
   }
 }