Improved handling of || expressions

This solves false "Unused variable" warnings of variables introduced in
right-hand side

Author: PaulKlint

.settings/org.eclipse.core.resources.prefs

@@ -1,7 +1,5 @@
 eclipse.preferences.version=1
 encoding//src/org/rascalmpl/core/library=UTF-8
-encoding//target/generated-test-resources=UTF-8
-encoding//target/generated-test-sources=UTF-8
 encoding/<project>=UTF-8
 encoding/src=UTF-8
 encoding/test=UTF-8

src/org/rascalmpl/core/library/lang/rascalcore/check/BasicRascalConfig.rsc

@@ -51,13 +51,14 @@ data PathRole
     ;
 
 data ScopeRole
-    = moduleScope()
-    | functionScope()
-    | conditionalScope()
+    = //moduleScope()
+     functionScope()
+    //| conditionalScope()
     | replacementScope()
     | visitOrSwitchScope()
-    | boolScope()
+    //| boolScope()
     | loopScope()
+    | orScope()
     ;
 
 data Vis

src/org/rascalmpl/core/library/lang/rascalcore/check/CollectOperators.rsc

@@ -756,7 +756,8 @@ void collect(current: (Expression) `<Expression lhs> && <Expression rhs>`, Colle
 }
 
 private set[str] introducedVars(Expression exp, Collector c){
-    return exp is match ? introducedVars(exp.pattern, c) : {};
+    return exp is \bracket ? introducedVars(exp.expression, c)
+                           : (exp is match ? introducedVars(exp.pattern, c) : {});
 }
 
 private set[str] introducedVars(Pattern e, Collector c){
@@ -793,6 +794,8 @@ private set[str] introducedVars(Pattern e, Collector c){
 
 // ---- or
 
+data OrInfo = orInfo(set[str] vars);
+ 
 void collect(current: (Expression) `<Expression lhs> || <Expression rhs>`, Collector c){
     c.fact(current, abool());
 
@@ -802,24 +805,22 @@ void collect(current: (Expression) `<Expression lhs> || <Expression rhs>`, Colle
             s.requireUnify(abool(), rhs, error(rhs, "Argument of || should be `bool`, found %t", rhs));
           });
 
-    // Check that the names introduced in lhs and rhs are the same    
+    collect(lhs, c);
 
     introLhs = introducedVars(lhs, c);
-    introRhs = introducedVars(rhs, c);
+    introRhs = introducedVars(rhs, c);  
 
-    collect(lhs, c);
+    // make common variables available when collecting rhs;
+    // variables in rhs will use definition from lhs (see CollectPattern: typed variable pattern, qualifiedName pattern)
+    c.setScopeInfo(c.getScope(), orScope(), orInfo(introLhs));
+    collect(rhs, c);
 
-    // Trick 1: wrap rhs in a separate scope to avoid double declarations with names introduced in lhs
-    // Trick 2: use "current" as scope (to avoid clash with scope created by rhs)
-    c.enterScope(lhs);
-        collect(rhs, c);
-    c.leaveScope(lhs);
+    // Check that the names introduced in lhs and rhs are the same    
+    common = introLhs & introRhs;
+    missing = (introLhs - common) + (introRhs - common);
 
-    for(nm <- introLhs){
-      if(nm notin introRhs) c.report(error(rhs, "Arguments of `||` should introduce same variables, right argument does not introduce `%v`", nm));
-    }
-    for(nm <- introRhs){
-      if(nm notin introLhs) c.report(error(lhs, "Arguments of `||` should introduce same variables, left argument does not introduce `%v`", nm));
+    if(!isEmpty(missing)){
+        c.report(error(current, "Variable(s) %v should be introduced on both sides of `||` operator", missing));
     }
 }
 

src/org/rascalmpl/core/library/lang/rascalcore/check/CollectPattern.rsc

@@ -78,6 +78,15 @@ void collect(current: (Pattern) `<Type tp> <Name name>`, Collector c){
                && c.isAlreadyDefined("<name>", name)){
               c.use(name, {variableId(), moduleVariableId(), formalId(), nestedFormalId(), patternVariableId()});
             } else {
+                orScopes = c.getScopeInfo(orScope());
+                for(<_, orInfo(vars)> <- orScopes){
+                    for(str id <- vars, id == uname){
+                        if(c.isAlreadyDefined("<name>", name)){
+                            c.use(name, {variableId(), formalId(), nestedFormalId(), patternVariableId()});
+                            return;
+                        }
+                    }
+                }
                 c.define(uname, formalOrPatternFormal(c), name, defType(tpResolved));
             }
         } else {

src/org/rascalmpl/core/library/lang/rascalcore/compile/Examples/Tst5.rsc

@@ -1,11 +1,5 @@
 module lang::rascalcore::compile::Examples::Tst5
 
-void main(){
-    previous = "non empty";
-     msg = "<for (x <- ["a", "b", "c"]) { continue;><x>
-           '<}>";
-}
-
 //MH
 //public void showUsageCounts(Corpus corpus, lrel[str p, str v, QueryResult qr] res) {
 //    mr = ( p : size([ e | <p,_,e> <- res ]) | p <- corpus );
@@ -19,6 +13,13 @@ void main(){
 //    return -1;
 //}
 
+value main(){
+    if ((j := 1) || (j := 2)) {
+        return j;
+    }
+    return -1;
+}
+
 
 //data Wrapper[&SAME] = something(&SAME wrapped);
 //