Change default behavior for cc_toolchain.compiler and cc_toolchain.libc for

platform-based toolchain selection to match legacy behavior.

This is a change over previous behavior in the platform case, which was to throw if either of those attributes is not present.  The default_toolchain field in CROSSTOOL gives a mapping from cc_toolchain.cpu values to toolchains - this map should be used with compiler and libc are not specified, as is currently the non-platforms, legacy behavior.

PiperOrigin-RevId: 176246316

1 files changed, 10 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchain.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchain.java
index f7fc13e4dc..c66dd9378b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchain.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchain.java
@@ -601,18 +601,21 @@ public class CcToolchain implements RuleConfiguredTargetFactory {
 
   private CToolchain getToolchainFromAttributes(
       RuleContext ruleContext, CppConfiguration cppConfiguration) throws RuleErrorException {
-    for (String requiredAttr : ImmutableList.of("cpu", "compiler", "libc")) {
-      if (ruleContext.attributes().get(requiredAttr, Type.STRING).isEmpty()) {
-        ruleContext.throwWithRuleError(
-            String.format(
-                "Using cc_toolchain target requires the attribute '%s' to be present.",
-                requiredAttr));
-      }
+    if (ruleContext.attributes().get("cpu", Type.STRING).isEmpty()) {
+      ruleContext.throwWithRuleError("Using cc_toolchain target requires the attribute 'cpu' "
+          + "to be present");
     }
 
+
     String cpu = ruleContext.attributes().get("cpu", Type.STRING);
     String compiler = ruleContext.attributes().get("compiler", Type.STRING);
+    if (compiler.isEmpty()) {
+      compiler = null;
+    }
     String libc = ruleContext.attributes().get("libc", Type.STRING);
+    if (libc.isEmpty()) {
+      libc = null;
+    }
     CrosstoolConfigurationIdentifier config =
         new CrosstoolConfigurationIdentifier(cpu, compiler, libc);