Normalize --add-exports= and --add-opens= flags

This is similar to the existing handling of `-source`, `-target`,
and `--release`, where (unlike javac) we allow all the options
to be mixed and matched, and let the last one win. With the
module-related flags, they are accumulated and added to the
command line only if the target level is 9 or higher, which
corresponds to modules being enabled.

PiperOrigin-RevId: 367471359

src/java_tools/buildjar/java/com/google/devtools/build/buildjar/javac/JavacOptions.java

@@ -17,6 +17,7 @@
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
+import com.google.common.primitives.Ints;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
@@ -230,6 +231,7 @@ public static class ReleaseOptionNormalizer implements JavacOptionNormalizer {
     private String source;
     private String target;
     private String release;
+    private final List<String> modular = new ArrayList<>();
 
     @Override
     public boolean processOption(String option, Iterator<String> remaining) {
@@ -253,6 +255,13 @@ public boolean processOption(String option, Iterator<String> remaining) {
             target = null;
           }
           return true;
+        case "--add-exports":
+        case "--add-opens":
+          if (remaining.hasNext()) {
+            modular.add(option);
+            modular.add(remaining.next());
+          }
+          return true;
         default: // fall out
       }
       if (option.startsWith("--release=")) {
@@ -261,11 +270,35 @@ public boolean processOption(String option, Iterator<String> remaining) {
         target = null;
         return true;
       }
+      if (option.startsWith("--add-exports=") || option.startsWith("--add-opens=")) {
+        modular.add(option);
+        return true;
+      }
       return false;
     }
 
+    private void addModular(List<String> normalized) {
+      String value;
+      if (release != null) {
+        value = release;
+      } else if (target != null) {
+        value = target;
+      } else {
+        return;
+      }
+      boolean hasPrefix = value.startsWith("1.");
+      Integer version = Ints.tryParse(hasPrefix ? value.substring("1.".length()) : value);
+      if (version == null) {
+        return;
+      }
+      if (version > 8) {
+        normalized.addAll(modular);
+      }
+    }
+
     @Override
     public void normalize(List<String> normalized) {
+      addModular(normalized);
       if (release != null) {
         normalized.add("--release");
         normalized.add(release);