[Driver] Verify GCCInstallation is valid

Summary:
Values returned by GCCInstallation.getParentLibPath() and
GCCInstallation.getTriple() are not valid unless
GCCInstallation.isValid() returns true. This has previously been
ignored, and the former two values were used without checking whether
GCCInstallation is valid. This led to the bad path "/../bin" being added
to the list of program paths.

author: danielmentz "Daniel Mentz <danielmentz@google.com>"

Reviewers: #clang, tstellar, srhines

Reviewed By: srhines

Subscribers: danielmentz, ormris, nickdesaulniers, srhines, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57930

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@361314 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Driver/ToolChains/Linux.cpp

@@ -234,9 +234,11 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   // used to target i386.
   // FIXME: This seems unlikely to be Linux-specific.
   ToolChain::path_list &PPaths = getProgramPaths();
-  PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
-                         GCCInstallation.getTriple().str() + "/bin")
-                       .str());
+  if (GCCInstallation.isValid()) {
+    PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
+                           GCCInstallation.getTriple().str() + "/bin")
+                         .str());
+  }
 
   Distro Distro(D.getVFS());
 

test/Driver/B-opt.c

@@ -20,3 +20,8 @@
 // RUN:     -B %S/Inputs/B_opt_tree/dir2 2>&1 -fuse-ld=ld \
 // RUN:   | FileCheck --check-prefix=CHECK-B-OPT-MULT %s
 // CHECK-B-OPT-MULT: "{{.*}}/Inputs/B_opt_tree/dir3{{/|\\\\}}prefix-ld"
+//
+// RUN: %clang -B %S/Inputs/does_not_exist -print-search-dirs \
+// RUN:     -target aarch64-linux-gnu \
+// RUN:   | FileCheck --check-prefix=CHECK-B-OPT-INVALID %s
+// CHECK-B-OPT-INVALID-NOT: /..//bin