small cleanup and handle escaped quotes in WGSL string lexing

Author: 39ali

docs/api-specs/debug_printf.md

@@ -12,6 +12,12 @@ This is a debugging extension and is not part of core WebGPU.
   - Vulkan with `VK_KHR_shader_non_semantic_info` support.
 
 On Vulkan, `debugPrintf` output is produced through the validation layer debug-printf path. It is not enabled when GPU-assisted validation is enabled, because the two validation features are mutually exclusive.
+To receive Vulkan `debugPrintf` output:
+
+- Install the Vulkan SDK.
+- Request `InstanceFlags::VALIDATION`.
+- Do not request `InstanceFlags::GPU_ASSISTED_VALIDATION`.
+- Listen for log messages at the `Info` level.
 
 ## WGSL Syntax
 

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

@@ -106,6 +106,20 @@ fn consume_any(input: &str, what: impl Fn(char) -> bool) -> (&str, &str) {
     input.split_at(pos)
 }
 
+fn find_string_literal_end(input: &str) -> Option<usize> {
+    let mut escaped = false;
+    for (index, c) in input.char_indices() {
+        if escaped {
+            escaped = false;
+        } else if c == '\\' {
+            escaped = true;
+        } else if c == '"' {
+            return Some(index);
+        }
+    }
+    None
+}
+
 struct UnclosedCandidate {
     index: usize,
     depth: usize,
@@ -273,17 +287,14 @@ fn consume_token(
         None => return (Token::End, ""),
     };
     match cur {
-        '"' => {
-            // Find the next quote in the remaining string
-            match chars.as_str().find('"') {
-                Some(len) => {
-                    let content = &chars.as_str()[..len];
-                    let rest = &chars.as_str()[len + 1..];
-                    (Token::String(content), rest)
-                }
-                None => (Token::Unknown('"'), chars.as_str()),
+        '"' => match find_string_literal_end(chars.as_str()) {
+            Some(len) => {
+                let content = &chars.as_str()[..len];
+                let rest = &chars.as_str()[len + 1..];
+                (Token::String(content), rest)
             }
-        }
+            None => (Token::Unknown('"'), chars.as_str()),
+        },
         ':' | ';' | ',' => (Token::Separator(cur), chars.as_str()),
         '.' => {
             let og_chars = chars.as_str();
@@ -978,6 +989,22 @@ fn test_tokens() {
     sub_test("No¾", &[Token::Word("No"), Token::Unknown('¾')]);
     sub_test("No好", &[Token::Word("No好")]);
     sub_test("_No", &[Token::Word("_No")]);
+    sub_test(
+        r#""debug \"value\": %d", next"#,
+        &[
+            Token::String(r#"debug \"value\": %d"#),
+            Token::Separator(','),
+            Token::Word("next"),
+        ],
+    );
+    sub_test(
+        r#""debug\\", next"#,
+        &[
+            Token::String(r#"debug\\"#),
+            Token::Separator(','),
+            Token::Word("next"),
+        ],
+    );
 
     sub_test_with_and_without_doc_comments(
         "*/*/***/*//=/*****//",

naga/src/valid/function.rs

@@ -236,8 +236,6 @@ pub enum FunctionError {
     MismatchedPayloadType(Handle<crate::Type>, Handle<crate::Type>),
     #[error("The payload passed to `traceRay` must be a pointer directly to a global variable")]
     PayloadPointerNotGlobal,
-    #[error("Expression {0:?} is used before it is defined/emitted")]
-    InvalidExpression(Handle<crate::Expression>),
     #[error("Argument {0:?} for `debugPrintf` must be a supported scalar type")]
     InvalidDebugPrintfArgument(Handle<crate::Expression>),
 }

naga/tests/out/spv/wgsl-debug-printf.spvasm.glsl

@@ -0,0 +1,9 @@
+#version 460
+#extension GL_EXT_debug_printf : require
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+
+void main()
+{
+    debugPrintfEXT("debug id: %u %u %u", gl_GlobalInvocationID.x, gl_GlobalInvocationID.y, gl_GlobalInvocationID.z);
+}
+