Restoring negative literal parsing behavior to ...

Restoring negative literal parsing behavior to what should be the least
surprising option. Thanks much to Johannes Rudolph for identifying the
bug in the bytecode generator which needed addressing for us to arrive
at proper -0.0 behavior, and for writing the majority of this patch.

A '-' followed immediately by either a number or a period should now
always be treated as a single numeric literal, which means the minus
binds more tightly than anything else. A specific example of how this
differs from 2.8 final is:

  -5.+(10) == 5.0   // and not -15.0

The full range of potentially ambiguous parses involving prefix
operators, numbers, and dots is quite large and still needs to be
completely and clearly specified.

Closes #2378 and #3657, review by odersky, jrudolph.

1 files changed, 16 insertions, 11 deletions

diff --git a/src/fjbg/ch/epfl/lamp/fjbg/JExtendedCode.java b/src/fjbg/ch/epfl/lamp/fjbg/JExtendedCode.java
index 523f960b23..69d0436528 100644
--- a/src/fjbg/ch/epfl/lamp/fjbg/JExtendedCode.java
+++ b/src/fjbg/ch/epfl/lamp/fjbg/JExtendedCode.java
@@ -146,27 +146,32 @@ public class JExtendedCode extends JCode {
     }
     public void emitPUSH(Long value) { emitPUSH(value.longValue()); }
 
-    public void emitPUSH(float value) {
-        if (value == 0.0F)
+    private static final Float ZEROF = Float.valueOf(0f);
+    private static final Float ONEF = Float.valueOf(1f);
+    private static final Float TWOF = Float.valueOf(2f);
+    public void emitPUSH(Float value) {
+        if (ZEROF.equals(value))
             emitFCONST_0();
-        else if (value == 1.0F)
+        else if (ONEF.equals(value))
             emitFCONST_1();
-        else if (value == 2.0F)
+        else if (TWOF.equals(value))
             emitFCONST_2();
         else
-            emitPUSH_index(pool.addFloat(value));
+            emitPUSH_index(pool.addFloat(value.floatValue()));
     }
-    public void emitPUSH(Float value) { emitPUSH(value.floatValue()); }
+    public void emitPUSH(float value) { emitPUSH(Float.valueOf(value)); }
 
-    public void emitPUSH(double value) {
-        if (value == 0.0)
+    private static final Double ZEROD = Double.valueOf(0d);
+    private static final Double ONED = Double.valueOf(1d);
+    public void emitPUSH(Double value) {
+        if (ZEROD.equals(value))
             emitDCONST_0();
-        else if (value == 1.0)
+        else if (ONED.equals(value))
             emitDCONST_1();
         else
-            emitLDC2_W(value);
+            emitLDC2_W(value.doubleValue());
     }
-    public void emitPUSH(Double value) { emitPUSH(value.doubleValue()); }
+    public void emitPUSH(double value) { emitPUSH(Double.valueOf(value)); }
 
     public void emitPUSH(String s) {
         emitPUSH_index(pool.addString(s));