Javac generates duplicate name_and_type constant pool entry for class BinaryOpValueExp.java

[Fredrik Öhrström]

but >>only<< if StringValueExp.java is put on the same command line.
If StringValueExp.java is left out from the comman dline, the generated 
class file for BinaryOpValueExp.java is fine.

Erik Joelsson found this bug while comparing the build results between 
the old build and the new build.

How to reproduce, first build a full jdk using the old buildsystem, then:
cd jdk/make/javax/management
<boot-jdk>/bin/java 
-Xbootclasspath/p:../../../../build/linux-amd64/langtools/dist/bootstrap/lib/javac.jar 
-jar 
../../../../build/linux-amd64/langtools/dist/bootstrap/lib/javac.jar 
-Xlint:-path -source 7 -target 7 -encoding ascii 
-Xbootclasspath:../../../../build/linux-amd64/classes -sourcepath 
../../../src/closed/solaris/classes:../../../src/closed/share/classes:../../../../build/linux-amd64/gensrc:../../../src/solaris/classes:../../../src/share/classes 
-d /tmp/classes 
../../../src/share/classes/javax/management/BinaryOpValueExp.java

A correct BinaryOpValueExp.class can be found below /tmp/classes

<boot-jdk>/bin/java 
-Xbootclasspath/p:../../../../build/linux-amd64/langtools/dist/bootstrap/lib/javac.jar 
-jar 
../../../../build/linux-amd64/langtools/dist/bootstrap/lib/javac.jar 
-Xlint:-path -source 7 -target 7 -encoding ascii 
-Xbootclasspath:../../../../build/linux-amd64/classes -sourcepath 
../../../src/closed/solaris/classes:../../../src/closed/share/classes:../../../../build/linux-amd64/gensrc:../../../src/solaris/classes:../../../src/share/classes 
-d /tmp/classes2 
../../../src/share/classes/javax/management/BinaryOpValueExp.java 
../../../src/share/classes/javax/management/StringValueExp.java

A BinaryOpValueExp.class with duplicate "<init>":(Ljava/lang/String;)V 
is created below /tmp/classes2

Javaps of the good and bad BinaryOpValueExp.class are attached.

Erik has found the commit in javac that causes this behaviour:

7181320: javac NullPointerException for switch labels with cast to 
String expressions
Reviewed-by: mcimadamore

--- a/src/share/classes/com/sun/tools/javac/code/Types.java    Fri Aug 17
17:30:03 2012 -0700
+++ b/src/share/classes/com/sun/tools/javac/code/Types.java    Mon Aug 20
21:24:10 2012 +0530
@@ -1589,9 +1589,16 @@ public class Types {
        * type parameters in t are deleted.
        */
       public Type erasure(Type t) {
-        return erasure(t, false);
+        return eraseNotNeeded(t)? t : erasure(t, false);
       }
       //where
+    private boolean eraseNotNeeded(Type t) {
+        // We don't want to erase primitive types and String type as that
+        // operation is idempotent. Also, erasing these could result in loss
+        // of information such as constant values attached to such types.
+        return (t.tag<= lastBaseTag) || (syms.stringType.tsym == t.tsym);
+    }
+

//Fredrik
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: binop.bad
Url: http://mail.openjdk.java.net/pipermail/compiler-dev/attachments/20120914/b71b4de1/binop.bad 
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: binop.good
Url: http://mail.openjdk.java.net/pipermail/compiler-dev/attachments/20120914/b71b4de1/binop.good