From f318595abd54c68603b4c1eb07b2f428184c06d9 Mon Sep 17 00:00:00 2001
From: Haisheng Yuan <h.yuan@alibaba-inc.com>
Date: Mon, 17 Sep 2018 12:03:09 -0500
Subject: [PATCH] [CALCITE-2506] Fix AssertionError in RexSimplify:
 coalesce(unaryPlus(nullInt), unaryPlus(vInt()))

---
 .../apache/calcite/rex/RexInterpreter.java    |  2 +
 .../org/apache/calcite/rex/RexSimplify.java   |  6 ++-
 .../calcite/test/RexProgramBuilderBase.java   |  2 +-
 .../apache/calcite/test/RexProgramTest.java   | 39 +++++++++++++++----
 4 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/core/src/main/java/org/apache/calcite/rex/RexInterpreter.java b/core/src/main/java/org/apache/calcite/rex/RexInterpreter.java
index a0455e2fd6a..212ed434efa 100644
--- a/core/src/main/java/org/apache/calcite/rex/RexInterpreter.java
+++ b/core/src/main/java/org/apache/calcite/rex/RexInterpreter.java
@@ -185,6 +185,8 @@ public Comparable visitCall(RexCall call) {
       return ceil(call, values);
     case EXTRACT:
       return extract(call, values);
+    case PLUS_PREFIX:
+      return containsNull(values) ? N : values.get(0);
     default:
       throw unbound(call);
     }
diff --git a/core/src/main/java/org/apache/calcite/rex/RexSimplify.java b/core/src/main/java/org/apache/calcite/rex/RexSimplify.java
index 1179547cbc3..c0aa0465e29 100644
--- a/core/src/main/java/org/apache/calcite/rex/RexSimplify.java
+++ b/core/src/main/java/org/apache/calcite/rex/RexSimplify.java
@@ -207,6 +207,8 @@ private RexNode simplify_(RexNode e) {
     case LESS_THAN_OR_EQUAL:
     case NOT_EQUALS:
       return simplifyComparison((RexCall) e);
+    case PLUS_PREFIX:
+      return simplify_(((RexCall) e).getOperands().get(0));
     default:
       return e;
     }
@@ -562,7 +564,9 @@ private RexNode simplifyCoalesce(RexCall call) {
     final List<RexNode> operands = new ArrayList<>();
     for (RexNode operand : call.getOperands()) {
       operand = simplify_(operand);
-      if (digests.add(operand.digest)) {
+      // Discard the first few NULL operands
+      if ((!operands.isEmpty() || !RexUtil.isNull(operand))
+          && digests.add(operand.digest)) {
         operands.add(operand);
       }
       if (!operand.getType().isNullable()) {
diff --git a/core/src/test/java/org/apache/calcite/test/RexProgramBuilderBase.java b/core/src/test/java/org/apache/calcite/test/RexProgramBuilderBase.java
index e3c651fdd11..3a7d980d1f0 100644
--- a/core/src/test/java/org/apache/calcite/test/RexProgramBuilderBase.java
+++ b/core/src/test/java/org/apache/calcite/test/RexProgramBuilderBase.java
@@ -468,7 +468,7 @@ protected RexNode vBoolNotNull(int arg) {
   /**
    * Creates {@code nullable int variable} with index of 0.
    * If you need several distinct variables, use {@link #vInt(int)}.
-   * The resulting node would look like {@code ?0.notNullInt0}
+   * The resulting node would look like {@code ?0.int0}
    *
    * @return nullable int variable with index of 0
    */
diff --git a/core/src/test/java/org/apache/calcite/test/RexProgramTest.java b/core/src/test/java/org/apache/calcite/test/RexProgramTest.java
index b76500a22f2..b14b3d11640 100644
--- a/core/src/test/java/org/apache/calcite/test/RexProgramTest.java
+++ b/core/src/test/java/org/apache/calcite/test/RexProgramTest.java
@@ -56,7 +56,6 @@
 import com.google.common.collect.Multimap;
 
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 
 import java.math.BigDecimal;
@@ -2090,14 +2089,40 @@ private void assertTypeAndToString(
         "IS DISTINCT FROM(?0.bool0, ?0.bool1)");
   }
 
-  @Ignore("[CALCITE-2505] java.lang.AssertionError: result mismatch")
-  @Test public void coalescePlusNull() {
-    // when applied to {?0.int0=-1},
-    // COALESCE(+(null), +(?0.int0)) yielded -1,
-    // and +(null) yielded NULL
+  @Test public void coalesceUnaryPlus() {
     checkSimplify2(
         coalesce(unaryPlus(nullInt), unaryPlus(vInt())),
-        "...", "...");
+        "?0.int0", "?0.int0");
+
+    checkSimplify2(
+        coalesce(unaryPlus(nullInt), unaryPlus(nullInt)),
+        "null", "null");
+
+    checkSimplify2(
+        coalesce(unaryPlus(nullInt), unaryPlus(nullInt), unaryPlus(vInt())),
+        "?0.int0", "?0.int0");
+
+    checkSimplify2(
+        coalesce(unaryPlus(nullInt), unaryPlus(nullInt),
+            unaryPlus(vInt()), unaryPlus(vInt(1))),
+        "COALESCE(?0.int0, ?0.int1)", "COALESCE(?0.int0, ?0.int1)");
+
+    checkSimplify2(
+        coalesce(unaryPlus(nullInt), unaryPlus(nullInt),
+            unaryPlus(vIntNotNull()), unaryPlus(vInt(1))),
+        "?0.notNullInt0", "?0.notNullInt0");
+
+    checkSimplify2(
+        coalesce(unaryPlus(vInt(0)), unaryPlus(vInt(1))),
+        "COALESCE(?0.int0, ?0.int1)", "COALESCE(?0.int0, ?0.int1)");
+
+    checkSimplify2(
+        coalesce(unaryPlus(vInt(0)), unaryPlus(nullInt), unaryPlus(vInt(1))),
+        "COALESCE(?0.int0, null, ?0.int1)", "COALESCE(?0.int0, null, ?0.int1)");
+
+    checkSimplify2(
+        coalesce(unaryPlus(vIntNotNull()), unaryPlus(nullInt), unaryPlus(vInt(1))),
+        "?0.notNullInt0", "?0.notNullInt0");
   }
 
   /** Converts a map to a string, sorting on the string representation of its