Fix expression evaluation problem

This CL fixes a bug in expression evaluator where we would
elevate a conditional dependency by mistake when it is not
read completely. This was caused by marking bit paths as
read in the same cycle.

There is still a potential bug in the code path where we
detect a variable would've already been calculated for a
dependency to be calculated (e.g. a ? a : b) but this
change is a fairly safe compared to making a big change
in that logic.

Bug: 895468
Change-Id: I60a704a59c3b5b8e4f833f060c6233d356dab6c8

3 files changed, 15 insertions, 12 deletions

diff --git a/compiler/src/main/java/android/databinding/tool/expr/Expr.java b/compiler/src/main/java/android/databinding/tool/expr/Expr.java
index 768a59a5..42d98a19 100644
--- a/compiler/src/main/java/android/databinding/tool/expr/Expr.java
+++ b/compiler/src/main/java/android/databinding/tool/expr/Expr.java
@@ -553,7 +553,8 @@ abstract public class Expr implements VersionProvider, LocationScopeProvider {
                     allCovered = false;
                     break;
                 }
-                final BitSet readForConditional = (BitSet) expr.findConditionalFlags().clone();
+                final BitSet readForConditional = (BitSet) expr
+                        .getShouldReadFlagsWithConditionals().clone();
 
                 // FIXME: this does not do full traversal so misses some cases
                 // to calculate that conditional, i should've read /readForConditional/ flags
diff --git a/compiler/src/main/java/android/databinding/tool/expr/ExprModel.java b/compiler/src/main/java/android/databinding/tool/expr/ExprModel.java
index e9cdfab2..87169cee 100644
--- a/compiler/src/main/java/android/databinding/tool/expr/ExprModel.java
+++ b/compiler/src/main/java/android/databinding/tool/expr/ExprModel.java
@@ -589,15 +589,17 @@ public class ExprModel {
                 }
             }
         }
-        for (Expr partialRead : markedSomeFlagsAsRead) {
-            // even if all paths are not satisfied, we can elevate certain conditional dependencies
-            // if all of their paths are satisfied.
-            for (Dependency dependency : partialRead.getDependants()) {
-                Expr dependant = dependency.getDependant();
-                if (dependant.isConditional() && dependant.getAllCalculationPaths()
-                        .areAllPathsSatisfied(partialRead.mReadSoFar)) {
-                    if (dependant.considerElevatingConditionals(partialRead)) {
-                        elevated = true;
+        if (!elevated) {
+            for (Expr partialRead : markedSomeFlagsAsRead) {
+                // even if all paths are not satisfied, we can elevate certain conditional
+                // dependencies if all of their paths are satisfied.
+                for (Dependency dependency : partialRead.getDependants()) {
+                    Expr dependant = dependency.getDependant();
+                    if (dependant.isConditional() && dependant.getAllCalculationPaths()
+                            .areAllPathsSatisfied(partialRead.mReadSoFar)) {
+                        if (dependant.considerElevatingConditionals(partialRead)) {
+                            elevated = true;
+                        }
                     }
                 }
             }
diff --git a/compiler/src/main/kotlin/android/databinding/tool/writer/LayoutBinderWriter.kt b/compiler/src/main/kotlin/android/databinding/tool/writer/LayoutBinderWriter.kt
index 6147519b..30b2583d 100644
--- a/compiler/src/main/kotlin/android/databinding/tool/writer/LayoutBinderWriter.kt
+++ b/compiler/src/main/kotlin/android/databinding/tool/writer/LayoutBinderWriter.kt
@@ -207,7 +207,7 @@ val Expr.callbackLocalName by lazyProp { expr : Expr ->
 }
 
 val Expr.executePendingLocalName by lazyProp { expr : Expr ->
-    if(expr.needsLocalField) "${expr.model.ext.getUniqueName(expr.readableName, Scope.EXECUTE_PENDING_METHOD, false)}"
+    if(expr.isDynamic || expr.needsLocalField) "${expr.model.ext.getUniqueName(expr.readableName, Scope.EXECUTE_PENDING_METHOD, false)}"
     else expr.toCode().generate()
 }
 
@@ -898,7 +898,7 @@ class LayoutBinderWriter(val layoutBinder : LayoutBinder) {
         if (model.flagMapping != null) {
             val mapping = model.flagMapping
             for (i in mapping.indices) {
-                tab("flag $i: ${mapping[i]}")
+                tab("flag $i (${longToBinary(1L + i)}): ${model.findFlagExpression(i)}")
             }
         }
         nl("flag mapping end*/")