better info in runtime constraint assertion

src/exec.js

@@ -1046,6 +1046,8 @@ function execSignalAssign(ctx, ast) {
 }
 
 function execConstrain(ctx, ast) {
+    ast.fileName = ctx.fileName;
+    ast.filePath = ctx.filePath;
     const a = exec(ctx, ast.values[0]);
     if (ctx.error) return;
     const b = exec(ctx, ast.values[1]);

src/gencode.js

@@ -422,11 +422,13 @@ function genConstrain(ctx, ast) {
     if (ctx.error) return;
     const b = gen(ctx, ast.values[1]);
     if (ctx.error) return;
-    return `ctx.assert(${a}, ${b})`;
+    const strErr = ast.fileName +": "+ast.first_line;
+    return `ctx.assert(${a}, ${b}, \"${strErr}\")`;
 }
 
 function genSignalAssignConstrain(ctx, ast) {
-    return genVarAssignement(ctx, ast) + ";\n" + genConstrain(ctx, ast);
+//    return genVarAssignement(ctx, ast) + ";\n" + genConstrain(ctx, ast);
+    return genVarAssignement(ctx, ast);
 }
 
 function genVarAddAssignement(ctx, ast) {