From ce6246502c4d4e43b158bd161859179ba606bf75 Mon Sep 17 00:00:00 2001
From: dan sinclair <dsinclair@chromium.org>
Date: Tue, 2 Aug 2022 21:17:05 +0000
Subject: [PATCH] Add `global_directive` rule to the WGSL parser.

This CL adds the `global_directive` rule into the WGSL parser and
moves `enable_directive` under that rule. This matches the WGSL
specification.

Bug: tint:1633
Change-Id: I48b809cd1d2f2ffa6ec0d83474c716d4015e1dea
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/98041
Auto-Submit: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Reviewed-by: Ben Clayton <bclayton@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
---
 src/tint/reader/wgsl/parser_impl.cc | 25 ++++++++++++++-----------
 src/tint/reader/wgsl/parser_impl.h  |  4 ++++
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/src/tint/reader/wgsl/parser_impl.cc b/src/tint/reader/wgsl/parser_impl.cc
index cdbe9c5f76..1f908d1569 100644
--- a/src/tint/reader/wgsl/parser_impl.cc
+++ b/src/tint/reader/wgsl/parser_impl.cc
@@ -310,7 +310,7 @@ bool ParserImpl::Parse() {
 }
 
 // translation_unit
-//  : enable_directive* global_decl* EOF
+//  : global_directive* global_decl* EOF
 void ParserImpl::translation_unit() {
     bool after_global_decl = false;
     while (continue_parsing()) {
@@ -319,17 +319,9 @@ void ParserImpl::translation_unit() {
             break;
         }
 
-        auto ed = enable_directive();
-        if (ed.matched) {
-            if (after_global_decl) {
-                add_error(p, "enable directives must come before all global declarations");
-            }
-        } else if (ed.errored) {
-            // Found a invalid enable directive.
-            continue;
-        } else {
+        auto ed = global_directive(after_global_decl);
+        if (!ed.matched && !ed.errored) {
             auto gd = global_decl();
-
             if (gd.matched) {
                 after_global_decl = true;
             }
@@ -347,6 +339,17 @@ void ParserImpl::translation_unit() {
     }
 }
 
+// global_directive
+//  : enable_directive
+Maybe<bool> ParserImpl::global_directive(bool have_parsed_decl) {
+    auto& p = peek();
+    auto ed = enable_directive();
+    if (ed.matched && have_parsed_decl) {
+        return add_error(p, "enable directives must come before all global declarations");
+    }
+    return ed;
+}
+
 // enable_directive
 //  : enable name SEMICLON
 Maybe<bool> ParserImpl::enable_directive() {
diff --git a/src/tint/reader/wgsl/parser_impl.h b/src/tint/reader/wgsl/parser_impl.h
index ce0090e582..6dfc13f401 100644
--- a/src/tint/reader/wgsl/parser_impl.h
+++ b/src/tint/reader/wgsl/parser_impl.h
@@ -385,6 +385,10 @@ class ParserImpl {
     void deprecated(const Source& source, const std::string& msg);
     /// Parses the `translation_unit` grammar element
     void translation_unit();
+    /// Parses the `global_directive` grammar element, erroring on parse failure.
+    /// @param has_parsed_decl flag indicating if the parser has consumed a global declaration.
+    /// @return true on parse success, otherwise an error or no-match.
+    Maybe<bool> global_directive(bool has_parsed_decl);
     /// Parses the `enable_directive` grammar element, erroring on parse failure.
     /// @return true on parse success, otherwise an error or no-match.
     Maybe<bool> enable_directive();