Changes in src/GenPoly/Specialize.cc [2ec65ad:a16764a6]

File:

• src/GenPoly/Specialize.cc (modified) (2 diffs)

src/GenPoly/Specialize.cc

@@ -200 +200 @@
         }
 
+        struct EnvTrimmer {
+                TypeSubstitution * env, * newEnv;
+                EnvTrimmer( TypeSubstitution * env, TypeSubstitution * newEnv ) : env( env ), newEnv( newEnv ){}
+                void previsit( TypeDecl * tyDecl ) {
+                        // transfer known bindings for seen type variables
+                        if ( Type * t = env->lookup( tyDecl->name ) ) {
+                                newEnv->add( tyDecl->name, t );
+                        }
+                }
+        };
+
+        /// reduce environment to just the parts that are referenced in a given expression
+        TypeSubstitution * trimEnv( ApplicationExpr * expr, TypeSubstitution * env ) {
+                if ( env ) {
+                        TypeSubstitution * newEnv = new TypeSubstitution();
+                        PassVisitor<EnvTrimmer> trimmer( env, newEnv );
+                        expr->accept( trimmer );
+                        return newEnv;
+                }
+                return nullptr;
+        }
+
         /// Generates a thunk that calls `actual` with type `funType` and returns its address
         Expression * Specialize::createThunkFunction( FunctionType *funType, Expression *actual, InferredParams *inferParams ) {
@@ -243 +265 @@
                 }
 
-                appExpr->env = TypeSubstitution::newFromExpr( appExpr, env );
+                appExpr->set_env( trimEnv( appExpr, env ) );
                 if ( inferParams ) {
                         appExpr->get_inferParams() = *inferParams;