LoadStatement: Keep the location of the path argument.

--
MOS_MIGRATED_REVID=102743954
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
index 9efd28e..7d2311c 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
@@ -670,6 +670,24 @@
     }
   }
 
+  /**
+   * Parse a String literal value, e.g. "str".
+   */
+  private StringLiteral parseStringLiteral() {
+    Preconditions.checkState(token.kind == TokenKind.STRING);
+    int end = token.right;
+    char quoteChar = lexer.charAt(token.left);
+    StringLiteral literal =
+        setLocation(new StringLiteral((String) token.value, quoteChar), token.left, end);
+
+    nextToken();
+    if (token.kind == TokenKind.STRING) {
+      reportError(lexer.createLocation(end, token.left),
+          "Implicit string concatenation is forbidden, use the + operator");
+    }
+    return literal;
+  }
+
   //  primary ::= INTEGER
   //            | STRING
   //            | STRING '.' IDENTIFIER funcall_suffix
@@ -691,17 +709,7 @@
         return literal;
       }
       case STRING: {
-        String value = (String) token.value;
-        int end = token.right;
-        char quoteChar = lexer.charAt(start);
-        nextToken();
-        if (token.kind == TokenKind.STRING) {
-          reportError(lexer.createLocation(end, token.left),
-              "Implicit string concatenation is forbidden, use the + operator");
-        }
-        StringLiteral literal = new StringLiteral(value, quoteChar);
-        setLocation(literal, start, end);
-        return literal;
+        return parseStringLiteral();
       }
       case IDENTIFIER: {
         Identifier ident = parseIdent();
@@ -1103,10 +1111,7 @@
       return;
     }
 
-    Token pathToken = token;
-    String path = (String) token.value;
-
-    nextToken();
+    StringLiteral path = parseStringLiteral();
     expect(TokenKind.COMMA);
 
     Map<Identifier, String> symbols = new HashMap<>();
@@ -1130,7 +1135,7 @@
     try {
       stmt.validatePath();
     } catch (EvalException e) {
-      syntaxError(pathToken, e.getMessage());
+      reportError(path.getLocation(), e.getMessage());
     }
 
     list.add(setLocation(stmt, start, token.left));