Improve error message when missing default_toolchain in CROSSTOOL

RELNOTES: None.
PiperOrigin-RevId: 176643685

1 files changed, 7 insertions, 3 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationOptions.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationOptions.java
index 16a05777a4..46af308d23 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationOptions.java
@@ -14,16 +14,20 @@
 
 package com.google.devtools.build.lib.rules.cpp;
 
+import javax.annotation.Nullable;
+
 /**
  * A container object which provides crosstool configuration options to the build.
  */
 public interface CrosstoolConfigurationOptions {
   /** Returns the CPU associated with this crosstool configuration. */
-  public String getCpu();
+  String getCpu();
 
   /** Returns the compiler associated with this crosstool configuration. */
-  public String getCompiler();
+  @Nullable
+  String getCompiler();
 
   /** Returns the libc version associated with this crosstool configuration. */
-  public String getLibc();
+  @Nullable
+  String getLibc();
 }