From f903eda8ab3ef6e3dfbaa0c6b274bad2fb35596f Mon Sep 17 00:00:00 2001
From: Stephen Chung <Stephen.Chung@intexact.com>
Date: Sat, 17 Oct 2020 18:18:29 +0800
Subject: [PATCH] Catch Fn and eval in method call at parse time.

---
 RELEASES.md    |  4 ++++
 src/fn_call.rs | 31 ++++++++++---------------------
 src/parser.rs  | 15 ++++++++++++++-
 3 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/RELEASES.md b/RELEASES.md
index 715003ed..9a7f9d08 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -11,6 +11,10 @@ Breaking changes
 * `EvalAltResult::ErrorReadingScriptFile` is removed in favor of the new `EvalAltResult::ErrorSystem`.
 * `EvalAltResult::ErrorLoopBreak` is renamed to `EvalAltResult::LoopBreak`.
 
+Enhancements
+
+* Calling `eval` or `Fn` in method-call style, which is an error, is now caught during parsing.
+
 
 Version 0.19.2
 ==============
diff --git a/src/fn_call.rs b/src/fn_call.rs
index 5785f1d2..43cbb9bb 100644
--- a/src/fn_call.rs
+++ b/src/fn_call.rs
@@ -524,27 +524,16 @@ impl Engine {
                 ))
             }
 
-            // Fn
-            KEYWORD_FN_PTR
-                if args.len() == 1 && !self.has_override(lib, hash_fn, hash_script, pub_only) =>
-            {
-                EvalAltResult::ErrorRuntime(
-                    "'Fn' should not be called in method style. Try Fn(...);".into(),
-                    Position::none(),
-                )
-                .into()
-            }
-
-            // eval - reaching this point it must be a method-style call
-            KEYWORD_EVAL
-                if args.len() == 1 && !self.has_override(lib, hash_fn, hash_script, pub_only) =>
-            {
-                EvalAltResult::ErrorRuntime(
-                    "'eval' should not be called in method style. Try eval(...);".into(),
-                    Position::none(),
-                )
-                .into()
-            }
+            // Fn/eval - reaching this point it must be a method-style call, mostly like redirected
+            //           by a function pointer so it isn't caught at parse time.
+            KEYWORD_FN_PTR | KEYWORD_EVAL if args.len() == 1 => EvalAltResult::ErrorRuntime(
+                format!(
+                    "'{}' should not be called in method style. Try {}(...);",
+                    fn_name, fn_name
+                ),
+                Position::none(),
+            )
+            .into(),
 
             // Script-like function found
             #[cfg(not(feature = "no_function"))]
diff --git a/src/parser.rs b/src/parser.rs
index 55d97082..a26ec543 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,7 +1,9 @@
 //! Main module defining the lexer and parser.
 
 use crate::any::{Dynamic, Union};
-use crate::engine::{Engine, KEYWORD_THIS, MARKER_BLOCK, MARKER_EXPR, MARKER_IDENT};
+use crate::engine::{
+    Engine, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_THIS, MARKER_BLOCK, MARKER_EXPR, MARKER_IDENT,
+};
 use crate::error::{LexError, ParseError, ParseErrorType};
 use crate::fn_native::{FnPtr, Shared};
 use crate::module::{Module, ModuleRef};
@@ -2318,6 +2320,17 @@ fn make_dot_expr(lhs: Expr, rhs: Expr, op_pos: Position) -> Result<Expr, ParseEr
                 op_pos,
             )))
         }
+        // lhs.Fn() or lhs.eval()
+        (_, Expr::FnCall(x))
+            if x.3.len() == 0 && [KEYWORD_FN_PTR, KEYWORD_EVAL].contains(&(x.0).0.as_ref()) =>
+        {
+            return Err(PERR::BadInput(format!(
+                "'{}' should not be called in method style. Try {}(...);",
+                (x.0).0,
+                (x.0).0
+            ))
+            .into_err((x.0).3));
+        }
         // lhs.func!(...)
         (_, Expr::FnCall(x)) if (x.0).2 => {
             return Err(PERR::MalformedCapture(