Fix include scanner's absolute path handling.

When absolute include dirs are used we can discover absolute includes outside any known root.

* Fix bug where we try to create an absolute exec path. Instead, make the exec path relative to the root directory '/'.
* Reverse the condition we use to filter absolute includes. We can identify these by their fake root ('/') before we create a path and linearly check if it is a system include.

PiperOrigin-RevId: 180217154

1 files changed, 8 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScanner.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScanner.java
index c3592846ee..b07f75e86f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScanner.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScanner.java
@@ -26,7 +26,6 @@ import com.google.devtools.build.lib.profiler.Profiler;
 import com.google.devtools.build.lib.profiler.ProfilerTask;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.PathFragment;
-
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -154,12 +153,14 @@ public interface IncludeScanner {
       // Collect inputs and output
       List<Artifact> inputs = new ArrayList<>();
       for (Artifact included : includes) {
-        if (FileSystemUtils.startsWithAny(included.getPath().asFragment(),
-            absoluteBuiltInIncludeDirs)) {
-          // Skip include files found in absolute include directories.
-          continue;
-        }
-        if (included.getRoot().getPath().getParentDirectory() == null) {
+        // Check for absolute includes -- we assign the file system root as
+        // the root path for such includes
+        if (included.getRoot().getPath().isRootDirectory()) {
+          if (FileSystemUtils.startsWithAny(
+              included.getPath().asFragment(), absoluteBuiltInIncludeDirs)) {
+            // Skip include files found in absolute include directories.
+            continue;
+          }
           throw new UserExecException(
               "illegal absolute path to include file: " + included.getPath());
         }