1 files changed, 49 insertions, 0 deletions
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 840e4c2734..c3c07f412f 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -183,6 +183,38 @@ static void addProfileRT(const ToolChain &TC, const ArgList &Args,
   CmdArgs.push_back(Args.MakeArgString(ProfileRT));
 }
 
+static void AddIncludeDirectoryList(const ArgList &Args,
+                                    ArgStringList &CmdArgs,
+                                    const char *ArgName,
+                                    const char *DirList) {
+  if (!DirList)
+    return; // Nothing to do.
+
+  StringRef Dirs(DirList);
+  if (Dirs.empty()) // Empty string should not add '.'.
+    return;
+
+  StringRef::size_type Delim;
+  while ((Delim = Dirs.find(llvm::sys::PathSeparator)) != StringRef::npos) {
+    if (Delim == 0) { // Leading colon.
+      CmdArgs.push_back(ArgName);
+      CmdArgs.push_back(".");
+    } else {
+      CmdArgs.push_back(ArgName);
+      CmdArgs.push_back(Args.MakeArgString(Dirs.substr(0, Delim)));
+    }
+    Dirs = Dirs.substr(Delim + 1);
+  }
+
+  if (Dirs.empty()) { // Trailing colon.
+    CmdArgs.push_back(ArgName);
+    CmdArgs.push_back(".");
+  } else { // Add the last path.
+    CmdArgs.push_back(ArgName);
+    CmdArgs.push_back(Args.MakeArgString(Dirs));
+  }
+}
+
 void Clang::AddPreprocessingOptions(const Driver &D,
                                     const ArgList &Args,
                                     ArgStringList &CmdArgs,
@@ -391,6 +423,23 @@ void Clang::AddPreprocessingOptions(const Driver &D,
   }
   
   Args.AddAllArgs(CmdArgs, options::OPT_fauto_module_import);
+
+  // Parse additional include paths from environment variables.
+  // CPATH - included following the user specified includes (but prior to
+  // builtin and standard includes).
+  AddIncludeDirectoryList(Args, CmdArgs, "-I", ::getenv("CPATH"));
+  // C_INCLUDE_PATH - system includes enabled when compiling C.
+  AddIncludeDirectoryList(Args, CmdArgs, "-c-isystem",
+                          ::getenv("C_INCLUDE_PATH"));
+  // CPLUS_INCLUDE_PATH - system includes enabled when compiling C++.
+  AddIncludeDirectoryList(Args, CmdArgs, "-cxx-isystem",
+                          ::getenv("CPLUS_INCLUDE_PATH"));
+  // OBJC_INCLUDE_PATH - system includes enabled when compiling ObjC.
+  AddIncludeDirectoryList(Args, CmdArgs, "-objc-isystem",
+                          ::getenv("OBJC_INCLUDE_PATH"));
+  // OBJCPLUS_INCLUDE_PATH - system includes enabled when compiling ObjC++.
+  AddIncludeDirectoryList(Args, CmdArgs, "-objcxx-isystem",
+                          ::getenv("OBJCPLUS_INCLUDE_PATH"));
 }
 
 /// getARMTargetCPU - Get the (LLVM) name of the ARM cpu we are targeting.