From 39b3d94beecf9348b41b2983dd8c96e153b2555a Mon Sep 17 00:00:00 2001
From: Noam Zaks <noam@noamzaks.com>
Date: Sat, 14 Jun 2025 23:35:59 +0300
Subject: [PATCH] Error on imports with keyword names

---
 crates/typst-eval/src/import.rs       |  4 ++++
 crates/typst-syntax/src/ast.rs        | 10 ++++++++--
 crates/typst-syntax/src/lexer.rs      |  6 ++++++
 crates/typst-syntax/src/lib.rs        |  4 ++--
 tests/suite/scripting/import.typ      |  5 +++++
 tests/suite/scripting/modules/set.typ |  1 +
 6 files changed, 26 insertions(+), 4 deletions(-)
 create mode 100644 tests/suite/scripting/modules/set.typ

diff --git a/crates/typst-eval/src/import.rs b/crates/typst-eval/src/import.rs
index 1b1641487..0749596c7 100644
--- a/crates/typst-eval/src/import.rs
+++ b/crates/typst-eval/src/import.rs
@@ -85,6 +85,10 @@ impl Eval for ast::ModuleImport<'_> {
                             source_span, "module name would not be a valid identifier";
                             hint: "you can rename the import with `as`",
                         ),
+                        Err(BareImportError::Keyword(name)) => bail!(
+                            source_span, "module `{name}` would be overridden as a keyword";
+                            hint: "you can rename the import with `as`",
+                        ),
                         // Bad package spec would have failed the import already.
                         Err(BareImportError::PackageInvalid) => unreachable!(),
                     }
diff --git a/crates/typst-syntax/src/ast.rs b/crates/typst-syntax/src/ast.rs
index 7b211bfc1..ab6ceb32f 100644
--- a/crates/typst-syntax/src/ast.rs
+++ b/crates/typst-syntax/src/ast.rs
@@ -86,7 +86,7 @@ use ecow::EcoString;
 use unscanny::Scanner;
 
 use crate::package::PackageSpec;
-use crate::{is_ident, is_newline, Span, SyntaxKind, SyntaxNode};
+use crate::{is_ident, is_keyword, is_newline, Span, SyntaxKind, SyntaxNode};
 
 /// A typed AST node.
 pub trait AstNode<'a>: Sized {
@@ -2223,6 +2223,10 @@ impl<'a> ModuleImport<'a> {
                     return Err(BareImportError::PathInvalid);
                 }
 
+                if is_keyword(&name) {
+                    return Err(BareImportError::Keyword(name));
+                }
+
                 Ok(name)
             }
             _ => Err(BareImportError::Dynamic),
@@ -2240,13 +2244,15 @@ impl<'a> ModuleImport<'a> {
 }
 
 /// Reasons why a bare name cannot be determined for an import source.
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+#[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub enum BareImportError {
     /// There is no statically resolvable binding name.
     Dynamic,
     /// The import source is not a valid path or the path stem not a valid
     /// identifier.
     PathInvalid,
+    /// The import source is a valid path but the path stem is a keyword.
+    Keyword(EcoString),
     /// The import source is not a valid package spec.
     PackageInvalid,
 }
diff --git a/crates/typst-syntax/src/lexer.rs b/crates/typst-syntax/src/lexer.rs
index 74f14cfeb..ee2bc11cc 100644
--- a/crates/typst-syntax/src/lexer.rs
+++ b/crates/typst-syntax/src/lexer.rs
@@ -1063,6 +1063,12 @@ pub fn is_ident(string: &str) -> bool {
         .is_some_and(|c| is_id_start(c) && chars.all(is_id_continue))
 }
 
+/// Whether a string is a Typst keyword.
+#[inline]
+pub fn is_keyword(string: &str) -> bool {
+    keyword(string).is_some()
+}
+
 /// Whether a character can start an identifier.
 #[inline]
 pub fn is_id_start(c: char) -> bool {
diff --git a/crates/typst-syntax/src/lib.rs b/crates/typst-syntax/src/lib.rs
index 4741506c5..50f2d7d3b 100644
--- a/crates/typst-syntax/src/lib.rs
+++ b/crates/typst-syntax/src/lib.rs
@@ -20,8 +20,8 @@ pub use self::file::FileId;
 pub use self::highlight::{highlight, highlight_html, Tag};
 pub use self::kind::SyntaxKind;
 pub use self::lexer::{
-    is_id_continue, is_id_start, is_ident, is_newline, is_valid_label_literal_id,
-    link_prefix, split_newlines,
+    is_id_continue, is_id_start, is_ident, is_keyword, is_newline,
+    is_valid_label_literal_id, link_prefix, split_newlines,
 };
 pub use self::lines::Lines;
 pub use self::node::{LinkedChildren, LinkedNode, Side, SyntaxError, SyntaxNode};
diff --git a/tests/suite/scripting/import.typ b/tests/suite/scripting/import.typ
index 382e444cc..4fc793bb1 100644
--- a/tests/suite/scripting/import.typ
+++ b/tests/suite/scripting/import.typ
@@ -483,3 +483,8 @@ This is never reached.
 --- import-from-file-package-lookalike ---
 // Error: 9-28 file not found (searched at tests/suite/scripting/#test/mypkg:1.0.0)
 #import "#test/mypkg:1.0.0": *
+
+--- import-keyword ---
+// Error: 9-26 module `set` would be overridden as a keyword
+// Hint: 9-26 you can rename the import with `as`
+#import "modules/set.typ"
diff --git a/tests/suite/scripting/modules/set.typ b/tests/suite/scripting/modules/set.typ
new file mode 100644
index 000000000..9138f3c3f
--- /dev/null
+++ b/tests/suite/scripting/modules/set.typ
@@ -0,0 +1 @@
+// SKIP