fix(wgsl-in): Handle Unterminated Block Comments (gfx-rs#9356)

Author: BKDaugherty

CHANGELOG.md

@@ -89,6 +89,7 @@ Bottom level categories:
 - Fixed overflow detection and argument domain validation for `acosh`, `length`, `normalize`, and `pow` in constant evaluation. By @ecoricemon in [#9249](https://github.com/gfx-rs/wgpu/pull/9249).
 - Naga no longer allows derivative operations on `f16`. WGSL does not currently allow this, although [it may be added in the future](https://github.com/gpuweb/gpuweb/issues/5482). By @andyleiserson in [#9154](https://github.com/gfx-rs/wgpu/pull/9154).
 - Disallow direct access to atomic variables in WGSL front-end (e.g. `let x = myAtomic;`). By @ecoricemon in [#9262](https://github.com/gfx-rs/wgpu/pull/9262).
+- Fixed handling of unterminated block comments. By @BKDaugherty in [#9356](https://github.com/gfx-rs/wgpu/pull/9356).
 
 #### dx12
 

cts_runner/test.lst

@@ -447,6 +447,7 @@ webgpu:shader,validation,parse,blankspace:bom:*
 webgpu:shader,validation,parse,blankspace:null_characters:contains_null=false;*
 webgpu:shader,validation,parse,blankspace:null_characters:contains_null=true;placement="delimiter"
 webgpu:shader,validation,parse,blankspace:null_characters:contains_null=true;placement="eol"
+webgpu:shader,validation,parse,comments:unterminated_block_comment:terminated=false
 webgpu:shader,validation,parse,enable:*
 webgpu:shader,validation,parse,identifiers:*
 webgpu:shader,validation,parse,requires:*

naga/src/front/wgsl/error.rs

@@ -442,6 +442,7 @@ pub(crate) enum Error<'a> {
     },
     UnexpectedExprForTypeExpression(Span),
     MissingIncomingPayload(Span),
+    UnterminatedBlockComment(Span),
 }
 
 impl From<ConflictingDiagnosticRuleError> for Error<'_> {
@@ -516,6 +517,7 @@ impl<'a> Error<'a> {
                         Token::DocComment(s) => format!("doc comment ('{s}')"),
                         Token::ModuleDocComment(s) => format!("module doc comment ('{s}')"),
                         Token::End => "end".to_string(),
+                        Token::UnterminatedBlockComment(s) => format!("unterminated doc comment ('{s}'")
                     },
                     ExpectedToken::Identifier => "identifier".to_string(),
                     ExpectedToken::LhsExpression => "LHS expression (identifier component_or_swizzle_specifier?, (`lhs_expression`) component_or_swizzle_specifier?, &`lhs_expression`, *`lhs_expression`)".to_string(),
@@ -1511,6 +1513,14 @@ impl<'a> Error<'a> {
                 )],
                 notes: vec![],
             },
+            Error::UnterminatedBlockComment(span) => ParseError {
+                message: "unterminated block comment".to_string(),
+                labels: vec![(
+                    span,
+                    "must be closed with `*/`".into(),
+                )],
+                notes: vec![],
+            }
         }
     }
 }

naga/src/front/wgsl/parse/lexer.rs

@@ -89,6 +89,11 @@ pub enum Token<'a> {
     /// A module-level doc comment, beginning with `//!` or `/*!`.
     ModuleDocComment(&'a str),
 
+    /// A block comment that is incomplete, and has not been closed with */.
+    ///
+    /// It's expected that the parser will consider this to be an error.
+    UnterminatedBlockComment(&'a str),
+
     /// The end of the input.
     End,
 }
@@ -360,7 +365,7 @@ fn consume_token(
                         }
                     }
 
-                    (Token::End, "")
+                    (Token::UnterminatedBlockComment(input), "")
                 }
                 Some('=') => (Token::AssignmentOperation(cur), chars.as_str()),
                 _ => (Token::Operation(cur), og_chars),
@@ -1263,3 +1268,11 @@ fn test_doc_comments_module() {
         ],
     );
 }
+
+#[test]
+fn test_block_comment_unclosed() {
+    sub_test_with_and_without_doc_comments(
+        "/** Unclosed Doc Comment",
+        &[Token::UnterminatedBlockComment("/** Unclosed Doc Comment")],
+    );
+}

naga/src/front/wgsl/parse/mod.rs

@@ -2192,6 +2192,9 @@ impl Parser {
                 Some(ast::GlobalDeclKind::ConstAssert(condition))
             }
             (Token::End, _) => return Ok(()),
+            (Token::UnterminatedBlockComment(_), span) => {
+                return Err(Box::new(Error::UnterminatedBlockComment(span)))
+            }
             other => {
                 return Err(Box::new(Error::Unexpected(
                     other.1,

naga/tests/naga/wgsl_errors.rs

@@ -5237,3 +5237,18 @@ fn bitwise_shift_errors() {
         naga::valid::Capabilities::SHADER_INT64
     }
 }
+
+#[test]
+fn unterminated_block_comment_errors() {
+    check_success("/* Closed */");
+
+    check_error_matches("/* unterminated", "unterminated block comment");
+    check_error_matches(
+        "/* unterminated /* terimated inner */",
+        "unterminated block comment",
+    );
+    check_error_matches(
+        "const N: u32 = 1u; /* Trailing unterminated",
+        "unterminated block comment",
+    )
+}