From c4f00afbeed90eb4f1accbb9c73cb184aaea205c Mon Sep 17 00:00:00 2001
From: Stephen Chung <Stephen.Chung@intexact.com>
Date: Mon, 12 Oct 2020 16:59:59 +0800
Subject: [PATCH] Disallow ! in module function calls.

---
 doc/src/language/fn-capture.md |  6 ++++++
 src/parser.rs                  | 12 +++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/doc/src/language/fn-capture.md b/doc/src/language/fn-capture.md
index 58ce811a..e35de979 100644
--- a/doc/src/language/fn-capture.md
+++ b/doc/src/language/fn-capture.md
@@ -43,6 +43,12 @@ let f = Fn("foo");
 call!(f, 41) == 42;     // must use function-call style
 
 f.call!(41);            // <- syntax error: capturing is not allowed in method-call style
+
+// Capturing is not available for module functions
+
+import "hello" as h;
+
+h::greet!();            // <- syntax error: capturing is not allowed in namespace-qualified calls
 ```
 
 
diff --git a/src/parser.rs b/src/parser.rs
index 4e932fe9..12f8660a 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1949,7 +1949,17 @@ fn parse_primary(
         settings.pos = token_pos;
 
         root_expr = match (root_expr, token) {
-            // Function call
+            // Qualified function call with !
+            #[cfg(not(feature = "no_closure"))]
+            (Expr::Variable(x), Token::Bang) if x.1.is_some() => {
+                return Err(if !match_token(input, Token::LeftParen)? {
+                    LexError::UnexpectedInput(Token::Bang.syntax().to_string()).into_err(token_pos)
+                } else {
+                    PERR::BadInput("'!' cannot be used to call module functions".to_string())
+                        .into_err(token_pos)
+                });
+            }
+            // Function call with !
             #[cfg(not(feature = "no_closure"))]
             (Expr::Variable(x), Token::Bang) => {
                 if !match_token(input, Token::LeftParen)? {