wgsl parser: Replace set_error() with add_error()

Have slightly different overloads.

Long term we will want to be able to emit more than one error in a single parse.

Bug: tint:282
Bug: tint:291
Change-Id: Ide61c6ca75d45065e917b8fa16a097048397e31b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/31723
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>

src/reader/wgsl/parser_impl.h

@@ -125,13 +125,22 @@ class ParserImpl {
   /// @param idx the index of the token to return
   /// @returns the token |idx| positions ahead without advancing
   Token peek(size_t idx);
-  /// Sets the error from |t|
-  /// @param t the token to set the error from
-  void set_error(const Token& t);
-  /// Sets the error from |t| or |msg| if |t| is not in error
-  /// @param t the token to set the error from
+  /// Appends an error at |t| with the message |msg|
+  /// @param t the token to associate the error with
   /// @param msg the error message
-  void set_error(const Token& t, const std::string& msg);
+  void add_error(const Token& t, const std::string& msg);
+  /// Appends an error raised when parsing |use| at |t| with the message |msg|
+  /// @param t the token to associate the error with
+  /// @param msg the error message
+  /// @param use a description of what was being parsed when the error was
+  /// raised.
+  void add_error(const Token& t,
+                 const std::string& msg,
+                 const std::string& use);
+  /// Appends an error at |source| with the message |msg|
+  /// @param source the source to associate the error with
+  /// @param msg the error message
+  void add_error(const Source& source, const std::string& msg);
 
   /// Registers a constructed type into the parser
   /// @param name the constructed name

src/reader/wgsl/parser_impl_error_msg_test.cc

@@ -289,7 +289,7 @@ TEST_F(ParserImplErrorTest, FunctionDeclDecoStageInvalid) {
 TEST_F(ParserImplErrorTest, FunctionDeclDecoStageTypeInvalid) {
   // TODO(bclayton) - BUG(https://crbug.com/tint/291)
   EXPECT("[[shader(vertex)]] fn main() -> void {}",
-         "test.wgsl:1:1 error: invalid token ([[) encountered\n"
+         "test.wgsl:1:1 error: invalid token\n"
          "[[shader(vertex)]] fn main() -> void {}\n"
          "^^\n");
 }
@@ -1178,7 +1178,7 @@ TEST_F(ParserImplErrorTest, UnaryInvalidExpr) {
 
 TEST_F(ParserImplErrorTest, UnexpectedToken) {
   EXPECT("unexpected",
-         "test.wgsl:1:1 error: invalid token (kIdentifier) encountered\n"
+         "test.wgsl:1:1 error: invalid token\n"
          "unexpected\n"
          "^^^^^^^^^^\n");
 }