Revert "[clang-cl] Always interpret the LIB env var as separated with semicolons"

This reverts commit 4d85444.

This commit broke building lldb's NativeProcessProtocolTest.cpp,
with errors like these:

In file included from include/llvm/Support/Process.h:32:0,
                 from tools/lldb/unittests/Host/NativeProcessProtocolTest.cpp:12:
include/llvm/Support/Program.h:39:11: error: reference to ‘pid_t’ is ambiguous
   typedef pid_t procid_t;

/usr/include/sched.h:38:17: note: candidates are: typedef __pid_t pid_t
 typedef __pid_t pid_t;

tools/lldb/include/lldb/lldb-types.h:85:18: note: typedef uint64_t lldb::pid_t
 typedef uint64_t pid_t;

Author: mstorsjo

clang/lib/Driver/Driver.cpp

@@ -2085,7 +2085,7 @@ bool Driver::DiagnoseInputExistence(const DerivedArgList &Args, StringRef Value,
 
   if (IsCLMode()) {
     if (!llvm::sys::path::is_absolute(Twine(Value)) &&
-        llvm::sys::Process::FindInEnvPath("LIB", Value, ';'))
+        llvm::sys::Process::FindInEnvPath("LIB", Value))
       return true;
 
     if (Args.hasArg(options::OPT__SLASH_link) && Ty == types::TY_Object) {

clang/test/Driver/cl-inputs.c

@@ -32,9 +32,7 @@
 // WARN-NOT: note
 
 // MSYS2_ARG_CONV_EXCL tells MSYS2 to skip conversion of the specified argument.
-// Add a dummy "other" entry to the path as well, to check that it's split
-// around semicolons even on unix.
-// RUN: env LIB="other;%S/Inputs/cl-libs" MSYS2_ARG_CONV_EXCL="/TP;/c" %clang_cl /c /TP cl-test.lib -### 2>&1 | FileCheck -check-prefix=TPlib %s
+// RUN: env LIB=%S/Inputs/cl-libs MSYS2_ARG_CONV_EXCL="/TP;/c" %clang_cl /c /TP cl-test.lib -### 2>&1 | FileCheck -check-prefix=TPlib %s
 // TPlib: warning: cl-test.lib: 'linker' input unused
 // TPlib: warning: argument unused during compilation: '/TP'
 // TPlib-NOT: cl-test.lib

llvm/include/llvm/Support/Process.h

@@ -29,7 +29,6 @@
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/Error.h"
-#include "llvm/Support/Program.h"
 #include <system_error>
 
 namespace llvm {
@@ -108,12 +107,10 @@ class Process {
   /// considered.
   static Optional<std::string> FindInEnvPath(StringRef EnvName,
                                              StringRef FileName,
-                                             ArrayRef<std::string> IgnoreList,
-                                             char Separator = EnvPathSeparator);
+                                             ArrayRef<std::string> IgnoreList);
 
   static Optional<std::string> FindInEnvPath(StringRef EnvName,
-                                             StringRef FileName,
-                                             char Separator = EnvPathSeparator);
+                                             StringRef FileName);
 
   // This functions ensures that the standard file descriptors (input, output,
   // and error) are properly mapped to a file descriptor before we use any of

llvm/lib/Support/Process.cpp

@@ -28,22 +28,21 @@ using namespace sys;
 //===          independent code.
 //===----------------------------------------------------------------------===//
 
-Optional<std::string>
-Process::FindInEnvPath(StringRef EnvName, StringRef FileName, char Separator) {
-  return FindInEnvPath(EnvName, FileName, {}, Separator);
+Optional<std::string> Process::FindInEnvPath(StringRef EnvName,
+                                             StringRef FileName) {
+  return FindInEnvPath(EnvName, FileName, {});
 }
 
 Optional<std::string> Process::FindInEnvPath(StringRef EnvName,
                                              StringRef FileName,
-                                             ArrayRef<std::string> IgnoreList,
-                                             char Separator) {
+                                             ArrayRef<std::string> IgnoreList) {
   assert(!path::is_absolute(FileName));
   Optional<std::string> FoundPath;
   Optional<std::string> OptPath = Process::GetEnv(EnvName);
   if (!OptPath.hasValue())
     return FoundPath;
 
-  const char EnvPathSeparatorStr[] = {Separator, '\0'};
+  const char EnvPathSeparatorStr[] = {EnvPathSeparator, '\0'};
   SmallVector<StringRef, 8> Dirs;
   SplitString(OptPath.getValue(), Dirs, EnvPathSeparatorStr);