Unconditionally include gcc's stdc-predef.h if it is available.

--
MOS_MIGRATED_REVID=89964638

4 files changed, 47 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
index c8139312f9..a38ec41425 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
@@ -297,6 +297,12 @@ public class CppCompileAction extends AbstractAction implements IncludeScannable
     return cppConfiguration.getBuiltInIncludeDirectories();
   }
 
+  @Nullable
+  @Override
+  public Artifact getBuiltInIncludeFile() {
+    return cppConfiguration.getBuiltInIncludeFile();
+  }
+
   public String getHostSystemName() {
     return cppConfiguration.getHostSystemName();
   }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
index 1fca0b4766..b3cdf3b82b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
@@ -26,6 +26,7 @@ import com.google.common.collect.Iterables;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.ArtifactFactory;
 import com.google.devtools.build.lib.actions.PackageRootResolver;
 import com.google.devtools.build.lib.actions.Root;
@@ -69,6 +70,8 @@ import java.util.Map;
 import java.util.Set;
 import java.util.zip.ZipException;
 
+import javax.annotation.Nullable;
+
 /**
  * This class represents the C/C++ parts of the {@link BuildConfiguration},
  * including the host architecture, target architecture, compiler version, and
@@ -190,6 +193,12 @@ public class CppConfiguration extends BuildConfiguration.Fragment {
   public static final String FDO_STAMP_MACRO = "BUILD_FDO_TYPE";
 
   /**
+   * This file (found under the sysroot) may be unconditionally included in every C/C++ compilation.
+   */
+  private static final PathFragment BUILT_IN_INCLUDE_PATH_FRAGMENT =
+      new PathFragment("include/stdc-predef.h");
+
+  /**
    * Represents an optional flag that can be toggled using the package features mechanism.
    */
   @VisibleForTesting
@@ -286,6 +295,7 @@ public class CppConfiguration extends BuildConfiguration.Fragment {
   private final PathFragment sysroot;
   private final PathFragment runtimeSysroot;
   private final List<PathFragment> builtInIncludeDirectories;
+  private Artifact builtInIncludeFile;
 
   private final Map<String, PathFragment> toolPaths;
   private final PathFragment ldExecutable;
@@ -1095,6 +1105,15 @@ public class CppConfiguration extends BuildConfiguration.Fragment {
   }
 
   /**
+   * Returns the built-in header automatically included by the toolchain compiler. All C++ files
+   * may implicitly include this file. May be null if {@link #getSysroot} is null.
+   */
+  @Nullable
+  public Artifact getBuiltInIncludeFile() {
+    return builtInIncludeFile;
+  }
+
+  /**
    * Returns the sysroot to be used. If the toolchain compiler does not support
    * different sysroots, or the sysroot is the same as the default sysroot, then
    * this method returns <code>null</code>.
@@ -1725,6 +1744,15 @@ public class CppConfiguration extends BuildConfiguration.Fragment {
   @Override
   public void prepareHook(Path execRoot, ArtifactFactory artifactFactory, PathFragment genfilesPath,
       PackageRootResolver resolver) throws ViewCreationFailedException {
+    // TODO(bazel-team): Remove the "relative" guard. sysroot should always be relative, and this
+    // should be enforced in the creation of CppConfiguration.
+    if (getSysroot() != null && !getSysroot().isAbsolute()) {
+      Root sysrootRoot = Iterables.getOnlyElement(
+          resolver.findPackageRoots(ImmutableList.of(getSysroot())).entrySet()).getValue();
+      builtInIncludeFile = Preconditions.checkNotNull(artifactFactory.getSourceArtifact(
+              sysroot.getRelative(BUILT_IN_INCLUDE_PATH_FRAGMENT), sysrootRoot),
+          "%s %s", sysrootRoot, sysroot);
+    }
     try {
       getFdoSupport().prepareToBuild(execRoot, genfilesPath, artifactFactory, resolver);
     } catch (ZipException e) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScannable.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScannable.java
index d1f89f9657..472e69bfde 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScannable.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/IncludeScannable.java
@@ -22,6 +22,8 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
+import javax.annotation.Nullable;
+
 /**
  * To be implemented by actions (such as C++ compilation steps) whose inputs
  * can be scanned to discover other implicit inputs (such as C++ header files).
@@ -68,6 +70,13 @@ public interface IncludeScannable {
   List<String> getCmdlineIncludes();
 
   /**
+   * Returns an artifact that the compiler may unconditionally include, even if the source file
+   * does not mention it.
+   */
+  @Nullable
+  Artifact getBuiltInIncludeFile();
+
+  /**
    * Returns the artifact relative to which the {@code getCmdlineIncludes()} should be interpreted. 
    */
   Artifact getMainIncludeScannerSource();
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 6929975569..82afb5c666 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
@@ -92,6 +92,10 @@ public interface IncludeScanner {
       Path execRoot = executor.getExecRoot();
 
       final List<Path> absoluteBuiltInIncludeDirs = new ArrayList<>();
+      Artifact builtInInclude = action.getBuiltInIncludeFile();
+      if (builtInInclude != null) {
+        includes.add(builtInInclude);
+      }
 
       Profiler profiler = Profiler.instance();
       try {