From 9d4b2f2dbdebe467c9628046aadf37afbb3444ad Mon Sep 17 00:00:00 2001
From: Mark Hills <mhills@acm.org>
Date: Tue, 19 Apr 2016 09:18:32 -0400
Subject: [PATCH] Now allow for names to be included as exceptions in scope
 conflict rules, resolves #947

---
 src/org/rascalmpl/library/lang/rascal/types/CheckTypes.rsc    | 2 +-
 src/org/rascalmpl/library/lang/rascal/types/CheckerConfig.rsc | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/org/rascalmpl/library/lang/rascal/types/CheckTypes.rsc b/src/org/rascalmpl/library/lang/rascal/types/CheckTypes.rsc
index f27cb3135ac..b360cb8e52c 100644
--- a/src/org/rascalmpl/library/lang/rascal/types/CheckTypes.rsc
+++ b/src/org/rascalmpl/library/lang/rascal/types/CheckTypes.rsc
@@ -296,7 +296,7 @@ public CheckResult checkExp(Expression exp:(Expression)`( <Expression ei> | <Exp
     // "it", since we have no information on which to base a reasonable assumption. 
     Symbol erType = t1;
     if (!isFailType(t1)) {
-        cRed = addLocalVariable(cRed, RSimpleName("it"), true, exp@\loc, erType);
+        cRed = addLocalVariable(cRed, RSimpleName("it"), true, exp@\loc, erType, allowedConflicts={RSimpleName("it")});
         < cRed, t3 > = checkExp(er, cRed);
         if (!isFailType(t3)) {
             if (!equivalent(erType,t3) && lub(erType,t3) == t3) {
diff --git a/src/org/rascalmpl/library/lang/rascal/types/CheckerConfig.rsc b/src/org/rascalmpl/library/lang/rascal/types/CheckerConfig.rsc
index aa0887471c9..7d1384672fe 100644
--- a/src/org/rascalmpl/library/lang/rascal/types/CheckerConfig.rsc
+++ b/src/org/rascalmpl/library/lang/rascal/types/CheckerConfig.rsc
@@ -339,7 +339,7 @@ public Configuration addImportedVariable(Configuration c, RName n, int varId, bo
 }
 
 @doc{Add a new local variable into the configuration.}
-public Configuration addLocalVariable(Configuration c, RName n, bool inf, loc l, Symbol rt) {
+public Configuration addLocalVariable(Configuration c, RName n, bool inf, loc l, Symbol rt, set[RName] allowedConflicts = { }) {
 	moduleId = head([i | i <- c.stack, c.store[i] is \module]);
 	moduleName = c.store[moduleId].name;
 
@@ -358,6 +358,8 @@ public Configuration addLocalVariable(Configuration c, RName n, bool inf, loc l,
 	
 	if (n notin c.fcvEnv) {
 		c.fcvEnv[n] = varId;
+	} else if (n in c.fcvEnv && n in allowedConflicts) {
+		c.fcvEnv[n] = varId;
 	} else {
 		// The name is already defined: what items are defined by this name?
 		conflictIds = (overload(ids,_) := c.store[c.fcvEnv[n]]) ? ids : { c.fcvEnv[n] };