serenity: LibJS: Lexer reports incorrect column for tokens

diff --git a/Libraries/LibJS/Lexer.cpp b/Libraries/LibJS/Lexer.cpp
index dc094f4f5..f67d8ff9b 100644
--- a/Libraries/LibJS/Lexer.cpp
+++ b/Libraries/LibJS/Lexer.cpp
@@ -149,8 +149,12 @@ Lexer::Lexer(StringView source)

 void Lexer::consume()
 {
-    if (m_position >= m_source.length()) {
-        m_position = m_source.length() + 1;
+    if (m_position > m_source.length())
+        return;
+
+    if (m_position == m_source.length()) {
+        m_position++;
+        m_line_column++;
         m_current_char = EOF;
         return;
     }
diff --git a/Libraries/LibJS/Lexer.h b/Libraries/LibJS/Lexer.h
index e60c2dd65..71f22b053 100644
--- a/Libraries/LibJS/Lexer.h
+++ b/Libraries/LibJS/Lexer.h
@@ -55,11 +55,11 @@ private:
     bool match(char, char, char, char) const;

     StringView m_source;
-    size_t m_position = 0;
+    size_t m_position { 0 };
     Token m_current_token;
-    int m_current_char = 0;
-    size_t m_line_number = 1;
-    size_t m_line_column = 1;
+    int m_current_char { 0 };
+    size_t m_line_number { 1 };
+    size_t m_line_column { 0 };

     struct TemplateState {
         bool in_expr;

Ultimately there are two issues.

1. m_line_column is initialized to 1 which leads to incorrect token line column numbers for tokens on the first line
2. after reading EOF m_line_column isn’t incremented one last time

After playing whack-a-mole for a while I think the above patch finally fixes both problems.

(notice in the test program only the tokens in the first line are off)

Not true, last line has line_column = 0 for the CurlyClose token, that should be 1.

I believe this is because when reading the last token it gets the wrong length,

if (m_position >= m_source.length()) {
        m_position = m_source.length() + 1;
        m_current_char = EOF;
        return;
    }

when m_position is m_source.length() it adds 1 for some reason so the length (m_position - value_start) becomes 2 which makes line_column 0.

(notice in the test program only the tokens in the first line are off)

Not true, last line has line_column = 0 for the CurlyClose token, that should be 1.

@linusg I believe you are the person to tag for LibJS 😃

don’t have to, but I appreciate it 😃

I’ll have a look.