Fix ordering of -fPIC for PIC compiles in the LTOBackendAction

For compiles that the CppConfiguration flags as needing PIC, the -fPIC
option needs to be added after the other compile options so that it cannot
be overridden (e.g. with a --copt). This is consistent with the way the
CppCompileAction compile options are ordered.

RELNOTES: None.
PiperOrigin-RevId: 156746218

1 files changed, 5 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java
index 32931bc719..9d900a01a0 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java
@@ -155,10 +155,14 @@ public final class LTOBackendArtifacts {
     Variables buildVariables = buildVariablesBuilder.build();
     List<String> execArgs = new ArrayList<>();
     execArgs.addAll(featureConfiguration.getCommandLine("lto-backend", buildVariables));
+    execArgs.addAll(commandLine);
+    // If this is a PIC compile (set based on the CppConfiguration), the PIC
+    // option should be added after the rest of the command line so that it
+    // cannot be overridden. This is consistent with the ordering in the
+    // CppCompileAction's compiler options.
     if (usePic) {
       execArgs.add("-fPIC");
     }
-    execArgs.addAll(commandLine);
     builder.addExecutableArguments(execArgs);
 
     ruleContext.registerAction(builder.build(ruleContext));