[lld] r287456 - Use Optional<std::string> instead of "" to represent a failure.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Sat Nov 19 13:23:58 2016
New Revision: 287456

URL: http://llvm.org/viewvc/llvm-project?rev=287456&view=rev
Log:
Use Optional<std::string> instead of "" to represent a failure.

Modified:
    lld/trunk/ELF/Driver.cpp
    lld/trunk/ELF/Driver.h
    lld/trunk/ELF/DriverUtils.cpp
    lld/trunk/ELF/LinkerScript.cpp

Modified: lld/trunk/ELF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.cpp?rev=287456&r1=287455&r2=287456&view=diff
==============================================================================
--- lld/trunk/ELF/Driver.cpp (original)
+++ lld/trunk/ELF/Driver.cpp Sat Nov 19 13:23:58 2016
@@ -186,11 +186,10 @@ Optional<MemoryBufferRef> LinkerDriver::
 
 // Add a given library by searching it from input search paths.
 void LinkerDriver::addLibrary(StringRef Name) {
-  std::string Path = searchLibrary(Name);
-  if (Path.empty())
-    error("unable to find library -l" + Name);
+  if (Optional<std::string> Path = searchLibrary(Name))
+    addFile(*Path);
   else
-    addFile(Path);
+    error("unable to find library -l" + Name);
 }
 
 // This function is called on startup. We need this for LTO since

Modified: lld/trunk/ELF/Driver.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.h?rev=287456&r1=287455&r2=287456&view=diff
==============================================================================
--- lld/trunk/ELF/Driver.h (original)
+++ lld/trunk/ELF/Driver.h Sat Nov 19 13:23:58 2016
@@ -72,8 +72,8 @@ std::vector<uint8_t> parseHexstring(Stri
 
 std::string createResponseFile(const llvm::opt::InputArgList &Args);
 
-std::string findFromSearchPaths(StringRef Path);
-std::string searchLibrary(StringRef Path);
+llvm::Optional<std::string> findFromSearchPaths(StringRef Path);
+llvm::Optional<std::string> searchLibrary(StringRef Path);
 
 } // namespace elf
 } // namespace lld

Modified: lld/trunk/ELF/DriverUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/DriverUtils.cpp?rev=287456&r1=287455&r2=287456&view=diff
==============================================================================
--- lld/trunk/ELF/DriverUtils.cpp (original)
+++ lld/trunk/ELF/DriverUtils.cpp Sat Nov 19 13:23:58 2016
@@ -138,24 +138,24 @@ static Optional<std::string> findFile(St
   return None;
 }
 
-std::string elf::findFromSearchPaths(StringRef Path) {
+Optional<std::string> elf::findFromSearchPaths(StringRef Path) {
   for (StringRef Dir : Config->SearchPaths)
     if (Optional<std::string> S = findFile(Dir, Path))
-      return *S;
-  return "";
+      return S;
+  return None;
 }
 
-// This is for -lfoo. We'll look for libfoo.so or libfoo.a from
-// search paths.
-std::string elf::searchLibrary(StringRef Name) {
+// Searches a given library from input search paths, which are filled
+// from -L command line switches. Returns a path to an existent library file.
+Optional<std::string> elf::searchLibrary(StringRef Name) {
   if (Name.startswith(":"))
     return findFromSearchPaths(Name.substr(1));
   for (StringRef Dir : Config->SearchPaths) {
     if (!Config->Static)
       if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".so"))
-        return *S;
+        return S;
     if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".a"))
-      return *S;
+      return S;
   }
-  return "";
+  return None;
 }

Modified: lld/trunk/ELF/LinkerScript.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.cpp?rev=287456&r1=287455&r2=287456&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.cpp (original)
+++ lld/trunk/ELF/LinkerScript.cpp Sat Nov 19 13:23:58 2016
@@ -1099,11 +1099,10 @@ void ScriptParser::addFile(StringRef S)
   } else if (sys::fs::exists(S)) {
     Driver->addFile(S);
   } else {
-    std::string Path = findFromSearchPaths(S);
-    if (Path.empty())
-      setError("unable to find " + S);
+    if (Optional<std::string> Path = findFromSearchPaths(S))
+      Driver->addFile(Saver.save(*Path));
     else
-      Driver->addFile(Saver.save(Path));
+      setError("unable to find " + S);
   }
 }