Let me investigate this bug. The issue is about inline code highlighting in LaTeX output adding whitespace at start and end. This is related to PR #10251 which activated syntax highlighting for the `code` role. Let me start by understanding the codebase structure and finding the relevant files. The bug is about LaTeX output for inline code with syntax highlighting. The `code` role with `:language:` option now produces syntax-highlighted output, but the LaTeX writer adds spaces at the start and end. Let me look at the relevant parts of the codebase.

Let me look at the relevant files to understand the issue.

Now I can see the issue. Let me look at the `visit_literal` method in the LaTeX translator more closely: ```python def visit_literal(self, node: Element) -> None: if self.in_title: self.body.append(r'\sphinxstyleliteralintitle{\sphinxupquote{') return elif 'kbd' in node['classes']: self.body.append(r'\sphinxkeyboard{\sphinxupquote{') return lang = node.get("language", None) if 'code' not in node['classes'] or not lang: self.body.append(r'\sphinxcode{\sphinxupquote{') return opts = self.config.highlight_options.get(lang, {}) hlcode = self.highlighter.highlight_block( node.astext(), lang, opts=opts, location=node) # TODO: Use nowrap option once LaTeX formatter supports it # https://github.com/pygments/pygments/pull/1343 hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} self.body.append(hlcode) self.body.append('}}') raise nodes.SkipNode ``` The issue is that `highlight_block` for LaTeX formatter wraps the code in `\begin{Verbatim}[commandchars=\\\{\}]` ... `\end{Verbatim}`. The code replaces the begin with `\sphinxcode{\sphinxupquote{` and strips the end. But the Verbatim environment adds newlines around the content. Let me look at what Pygments' LaTeX formatter produces. The typical output of Pygments for LaTeX is: ``` \begin{Verbatim}[commandchars=\\\{\}] \PYG{k}{def} \PYG{n+nf}{foo}\PYG{p}{(}\PYG{l+m+mi}{1} \PYG{o}{+} \PYG{l+m+mi}{2} \PYG{o}{+} \PYG{k+kc}{None} \PYG{o}{+} \PYG{l+s+s2}{\PYGZdq{}}\PYG{l+s+s2}{abc}\PYG{l+s+s2}{\PYGZdq{}}\PYG{p}{)}\PYG{p}{:} \PYG{k}{pass} \end{Verbatim} ``` So after the replacement, we get: ``` \sphinxcode{\sphinxupquote{ \PYG{k}{def} \PYG{n+nf}{foo}\PYG{p}{(}\PYG{l+m+mi}{1} \PYG{o}{+} \PYG{l+m+mi}{2} \PYG{o}{+} \PYG{k+kc}{None} \PYG{o}{+} \PYG{l+s+s2}{\PYGZdq{}}\PYG{l+s+s2}{abc}\PYG{l+s+s2}{\PYGZdq{}}\PYG{p}{)}\PYG{p}{:} \PYG{k}{pass} }} ``` The newline after `{` and before `}` creates whitespace in the LaTeX output. In LaTeX, a newline is equivalent to a space. The fix should strip the newline after the opening brace and before the closing brace. Let's look more carefully at what `highlight_block` returns. Actually, let me look at the Pygments LaTeX formatter to understand the exact output format. But first, let me trace the exact flow. `self.highlighter.highlight_block()` is called. Let me check what this does.

Let me look at how `highlight_block` works and what it returns:

Now I see the flow. `highlight_block` calls `texescape.hlescape` on the result for LaTeX output. Let me check `texescape.hlescape` to see what it does. But the key issue is in `visit_literal` in the LaTeX translator. When `highlight_block` is called, it produces output like: ``` \begin{Verbatim}[commandchars=\\\{\}] \PYG{k}{def} ... \end{Verbatim} ``` Then in `visit_literal`: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{') hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} self.body.append(hlcode) self.body.append('}}') ``` After replacement, the `hlcode` looks like: ``` \sphinxcode{\sphinxupquote{\n\PYG{k}{def} ...\n}} ``` The `\n` after `{` and before `}` produce whitespace in LaTeX. Wait, but actually looking at the `visit_literal` code more carefully: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} self.body.append(hlcode) self.body.append('}}') ``` The `\begin{Verbatim}[commandchars=\\\{\}]` is at the start. Its replacement includes `\sphinxcode{\sphinxupquote{`. Then `\end{Verbatim}` is stripped (last 14 chars). Then `}}` is appended. But `hlcode` still contains a newline right after the opening `\sphinxcode{\sphinxupquote{` (from the Verbatim environment's newline after `\begin{Verbatim}...`), and a newline before the closing `}}` (which was before `\end{Verbatim}`). The fix should be to strip these newlines. We could either: 1. Strip leading and trailing whitespace from `hlcode` after the replacement 2. Or use `%` comments in LaTeX to suppress the newlines Option 1 would remove the whitespace from the LaTeX source, but it might also remove legitimate spaces in the highlighted code. But wait, the highlighted code content is in between - the newlines we want to remove are just the ones immediately after `{` and before `}`. Actually, let's think about this more carefully. In the Verbatim environment output: ``` \begin{Verbatim}[commandchars=\\\{\}]\n \PYG{k}{def} \PYG{n+nf}{foo}\PYG{p}{(}\PYG{l+m+mi}{1} \PYG{o}{+} ...\PYG{k}{pass}\n \end{Verbatim} ``` After the `replace`: ``` \sphinxcode{\sphinxupquote{\n \PYG{k}{def} \PYG{n+nf}{foo}\PYG{p}{(}\PYG{l+m+mi}{1} \PYG{o}{+} ...\PYG{k}{pass}\n \end{Verbatim} ``` After `.rstrip()[:-14]`: ``` \sphinxcode{\sphinxupquote{\n \PYG{k}{def} \PYG{n+nf}{foo}\PYG{p}{(}\PYG{l+m+mi}{1} \PYG{o}{+} ...\PYG{k}{pass} ``` Then `}}` is appended: ``` \sphinxcode{\sphinxupquote{\n \PYG{k}{def} \PYG{n+nf}{foo}\PYG{p}{(}\PYG{l+m+mi}{1} \PYG{o}{+} ...\PYG{k}{pass} }} ``` So the issue is that there's a `\n` right after `\sphinxupquote{` which in LaTeX is treated as whitespace, causing a space at the start. And there's a `\n` before `}}` which is also a space at the end. The fix should trim this. The simplest approach would be: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{%') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} hlcode = hlcode.rstrip() + '%' self.body.append(hlcode) self.body.append('}}') ``` Wait, but using `%` would comment out the rest of the line. Let me think again... Actually, the standard approach in the Sphinx LaTeX writer is to use `%` at the end of lines to suppress the newline-as-space behavior. Let me look at how other parts handle this. Looking at the `visit_literal` code for the non-highlighted case: ```python self.body.append(r'\sphinxcode{\sphinxupquote{') return ``` And `depart_literal`: ```python self.body.append('}}') ``` In this case, the content between `visit_literal` and `depart_literal` is processed by other visitors (like `visit_Text`), which don't add newlines. But for the highlighted case, the `highlight_block` produces a string that includes newlines from the Verbatim environmen ... [truncated 8,632 characters]

Let me check what the Pygments LaTeX formatter actually produces:

So the output is: ``` \begin{Verbatim}[commandchars=\\\{\}]\n\PYG{k}{def} ...\n\end{Verbatim}\n ``` There's a trailing `\n` after `\end{Verbatim}` too. Now let's trace through the `highlight_block` method and `visit_literal`: 1. `highlight_block` calls `highlight(source, lexer, formatter)` which returns the above string. 2. Then it calls `texescape.hlescape(hlsource, self.latex_engine)`. Let me check what `hlescape` does.

Now I have a clear picture. The `hlescape` function doesn't add or remove newlines - it just translates certain characters. So the issue is in `visit_literal` in the LaTeX writer. After `highlight_block` returns, we get something like: ``` \begin{Verbatim}[commandchars=\\\{\}]\n\PYG{k}{def} ...\n\end{Verbatim}\n ``` Then: 1. `replace` changes the begin to `\sphinxcode{\sphinxupquote{` 2. `rstrip()` removes the trailing `\n` 3. `[:-14]` removes `\end{Verbatim}` Result: ``` \sphinxcode{\sphinxupquote{\n\PYG{k}{def} ... ``` Then `}}` is appended: ``` \sphinxcode{\sphinxupquote{\n\PYG{k}{def} ...}} ``` So there's a leading `\n` after `{` and a trailing space before `}}` (from the `\n` that was before `\end{Verbatim}` which was NOT stripped because `rstrip()` only strips from the end, and `[:-14]` removed `\end{Verbatim}` but the `\n` before it is still there... wait no, `rstrip()` strips from the end. The string is `...\n\end{Verbatim}\n`. `rstrip()` strips trailing whitespace, i.e., the final `\n`. Then `[:-14]` removes `\end{Verbatim}`, but the `\n` before `\end{Verbatim}` is still there. So the result is `\sphinxcode{\sphinxupquote{\n\PYG{k}{def} ...\n`. Wait, I need to check: is there a `\n` before `\end{Verbatim}`? Let me check the Pygments output again: ``` '\begin{Verbatim}[commandchars=\\\\\\{\\}]\n\\PYG{k}{def} \\PYG{n+nf}{foo}\\PYG{p}{(}\\PYG{l+m+mi}{1} \\PYG{o}{+} \\PYG{l+m+mi}{2} \\PYG{o}{+} \\PYG{k+kc}{None} \\PYG{o}{+} \\PYG{l+s+s2}{\\PYGZdq{}}\\PYG{l+s+s2}{abc}\\PYG{l+s+s2}{\\PYGZdq{}}\\PYG{p}{)}\\PYG{p}{:} \\PYG{k}{pass}\n\\end{Verbatim}\n' ``` Yes, there's a `\n` before `\end{Verbatim}`. So after `rstrip()` (which removes the trailing `\n`), and `[:-14]` (which removes `\end{Verbatim}`), we get: ``` \sphinxcode{\sphinxupquote{\n\PYG{k}{def} ... \PYG{k}{pass}\n ``` So there's a leading `\n` and a trailing `\n` in the highlighted code content. Both of these produce unwanted spaces in LaTeX output. Now, the fix. I think the cleanest approach is to strip the leading and trailing whitespace from `hlcode` after all the processing, since the highlighted code content shouldn't have meaningful leading/trailing whitespace for inline code. But wait - we need to be careful. The `hlcode` after processing is: ``` \sphinxcode{\sphinxupquote{\n\PYG{k}{def} ... \PYG{k}{pass}\n ``` If we just `.strip()` this, it would remove the leading `\n` but also the trailing `\n`. But `strip()` only removes whitespace, and the highlighted code tokens don't have leading/trailing whitespace (they're Pygments commands like `\PYG{k}{def}`). Actually, let me check: could there be leading/trailing spaces in the highlighted code? For example, if the code is ` def foo(): pass `, would there be leading/trailing spaces in the output? Let me test:

So leading/trailing spaces in the code ARE preserved by Pygments (which makes sense - they're part of the code). So we shouldn't use `.strip()` because that would remove legitimate leading/trailing spaces from the code. The issue is specifically with the newlines that come from the Verbatim environment wrapping. The newline after `\begin{Verbatim}[commandchars=\\\{\}]` and the newline before `\end{Verbatim}` are not part of the code - they are part of the LaTeX environment structure. So the correct fix is to use LaTeX `%` comments to suppress the newlines. Let me look at how the replacement should work: After `replace`: ``` \sphinxcode{\sphinxupquote{\n \PYG{k}{def} ... \PYG{k}{pass} \n\end{Verbatim} ``` We need to change the first `\n` (after `\sphinxupquote{`) to be commented out with `%`, and the last `\n` (before `\end{Verbatim}`) to be commented out. But we're replacing the `\begin{Verbatim}[commandchars=\\\{\}]` with `\sphinxcode{\sphinxupquote{`. Instead, we could replace it with `\sphinxcode{\sphinxupquote{%` which would comment out the newline. For the trailing newline before `}}`, we need to handle it differently. After `rstrip()[:-14]` we have: ``` \sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} \n ``` Wait, if we use `%` at the start, it comments out the rest of the line, which would include the highlighted code! That's wrong. Let me re-think. The `%` in LaTeX comments out everything from `%` to the end of the line. So `\sphinxupquote{%\n` would comment out the `\n` but NOT the highlighted code on the next line. Because `%` only affects the current line. So: ``` \sphinxcode{\sphinxupquote{% \PYG{k}{def} ... ``` The `%` comments out the newline (and anything else on that line, but there's nothing else). The next line starts with `\PYG{k}{def}...` which is not commented out. This would work! Similarly, for the trailing part, we need to add `%` before the closing `}}` but after the highlighted code. The highlighted code has a trailing `\n` that we want to suppress. We could do: ``` \PYG{k}{pass}% }} ``` But we can't easily insert `%` in the middle of `hlcode`. Alternatively, we could just replace the trailing `\n` with `%` before appending `}}`: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{%') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} hlcode = hlcode.rstrip() + '%' self.body.append(hlcode) self.body.append('}}') ``` Wait, but `rstrip()` would also strip trailing spaces from the highlighted code. Let me think about this... After replace: `\sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} \n\end{Verbatim}\n` After `rstrip()` (strips trailing `\n`): `\sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} \n\end{Verbatim}` After `[:-14]`: `\sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} \n` Then `hlcode.rstrip() + '%'`: This would strip the trailing `\n` and spaces after `pass`, giving `\sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass}%`... But wait, that would remove the trailing spaces from the highlighted code (` ` after `pass`)! That's wrong - those trailing spaces might be meaningful. Hmm, this is tricky. Let me reconsider. Actually, `rstrip()` only removes whitespace characters (spaces, tabs, newlines). If the code has trailing spaces, those would be removed. But is that really a problem for inline code? Typically inline code doesn't have meaningful trailing whitespace. But to be safe, we should only remove the newlines, not spaces. Let me think of another approach. Maybe we should just strip exactly one leading `\n` and one trailing `\n`: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} # Remove the leading and trailing newline from Verba ... [truncated 1,560 characters]

OK so `hlescape` doesn't change the newlines. The output format is: ``` \begin{Verbatim}[commandchars=\\\{\}]\n<code>\n\end{Verbatim}\n ``` Now let me look at the exact processing in `visit_literal`: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} self.body.append(hlcode) self.body.append('}}') ``` After replace: ``` \sphinxcode{\sphinxupquote{\n<code>\n\end{Verbatim}\n ``` After `rstrip()`: ``` \sphinxcode{\sphinxupquote{\n<code>\n\end{Verbatim} ``` After `[:-14]`: ``` \sphinxcode{\sphinxupquote{\n<code>\n ``` Then `}}` is appended: ``` \sphinxcode{\sphinxupquote{\n<code>\n}} ``` So both a leading and trailing `\n` are included, which produce spaces in LaTeX. Now, the fix should remove these newlines. The safest approach is to use `%` to comment them out in LaTeX. Let me look at how to modify the code: For the leading newline: change the replacement to include `%`: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{%') ``` This would produce: ``` \sphinxcode{\sphinxupquote{%\n<code>\n\end{Verbatim}\n ``` The `%` comments out the `\n` and we're good for the start. For the trailing newline: we need to add `%` before the closing `}}`. After `rstrip()[:-14]`: ``` \sphinxcode{\sphinxupquote{%\n<code>\n ``` We need to change the trailing `\n` to `%\n` or just `%`. But we can't use `rstrip()` because that would also strip spaces from the code. Wait actually, can we check if it ends with `\n` and if so, replace it with `%`? ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{%') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} if hlcode.endswith('\n'): hlcode = hlcode[:-1] + '%' self.body.append(hlcode) self.body.append('}}') ``` But wait, what if the code itself ends with a newline? No, for inline code, `node.astext()` returns the text without trailing newlines. But let me verify: what does `node.astext()` return for the inline code? The inline code text is `def foo(1 + 2 + None + "abc"): pass` - no trailing newline. So the highlighted code won't end with a newline from the code itself. The only newlines come from the Verbatim environment wrapper. So we can safely strip exactly one leading `\n` and one trailing `\n`. Actually, the simplest and most robust fix: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{%') # get consistent trailer hlcode = hlcode.rstrip()[:-14] # strip \end{Verbatim} # remove the trailing newline (from before \end{Verbatim}) if hlcode.endswith('\n'): hlcode = hlcode[:-1] self.body.append(hlcode) self.body.append('}}') ``` The leading `%` handles the leading newline, and the `if hlcode.endswith('\n')` handles the trailing newline. Wait, but what if the highlighted code itself has trailing content after the last token? Let me check with leading/trailing spaces: For code ` def foo(): pass `, the output is: ``` \begin{Verbatim}[commandchars=\\\{\}]\n \PYG{k}{def} ... \PYG{k}{pass} \n\end{Verbatim}\n ``` After replace with `%`: ``` \sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} \n\end{Verbatim}\n ``` After `rstrip()`: ``` \sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} \n\end{Verbatim} ``` After `[:-14]`: ``` \sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} \n ``` The trailing `\n` is separate from the code's trailing spaces. So `if hlcode.endswith('\n'): hlcode = hlcode[:-1]` would only remove the `\n`, leaving the spaces intact. Then we'd have: ``` \sphinxcode{\sphinxupquote{%\n \PYG{k}{def} ... \PYG{k}{pass} }} ``` The `%` comments out the first newline, and the trailing `\n` before `}}` is removed. ... [truncated 2,556 characters]

Now I understand the issue. Let me verify the exact output format and look at the specific code path:

Wait, the replace didn't work in my test because I escaped things incorrectly. Let me check the actual behavior. The replace in the code uses raw strings: ```python hlcode = hlcode.replace(r'\begin{Verbatim}[commandchars=\\\{\}]', r'\sphinxcode{\sphinxupquote{') ``` The raw string `r'\begin{Verbatim}[commandchars=\\\{\}]'` is literally `\begin{Verbatim}[commandchars=\\\{\}]` in the string. But the actual string from Pygments has `\\` for each backslash? Let me look... Actually, the Pygments output (as a Python string) is: ``` '\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n...' ``` So in the actual string, the characters are: `\begin{Verbatim}[commandchars=\\\{\}]`. That's one backslash for `\begin`, then `[commandchars=\`, then two backslashes `\\`, then `{`, then two backslashes `\\`, then `}]`. Wait, let me decode the Python representation: `\\\\begin` means two backslash characters followed by `begin`. But that's because the formatter is called with `commandprefix='PYG'`, and the Verbatim commandchars... Actually let me just look at the actual string. The Python repr is: ``` '\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n...' ``` Let me decode character by character: - `\\` → `\` - `begin` → `begin` - `{Verbatim}[commandchars=` → `{Verbatim}[commandchars=` - `\\\\` → `\\` - `\\` → `\` - `{` → `{` - `\\` → `\` - `}` → `}` - `]` → `]` So the actual string content is: `\begin{Verbatim}[commandchars=\\\{\}]` And the replace pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'` in raw string is: `\begin{Verbatim}[commandchars=\\\{\}]` — that matches. But wait, in my test I used regular strings and escaped things differently. Let me redo the test properly. Actually, let me just focus on the fix. The key issue is clear: after the replace and strip operations, there's a leading `\n` and a trailing `\n` that get included in the LaTeX output, producing unwanted spaces. Let me now write the fix.

Interesting - the replace didn't work! The output still has `\begin{Verbatim}[commandchars=\\\{\}]`. Let me check why. Looking at the actual characters list: `'\\', 'b', 'e', 'g', 'i', 'n', '{', 'V', 'e', 'r', 'b', 'a', 't', 'i', 'm', '}', '[', 'c', 'o', 'm', 'm', 'a', 'n', 'd', 'c', 'h', 'a', 'r', 's', '=', '\\', '\\', '\\', '{', '\\', '}', ']'` So the actual characters are: - `\`, `b`, `e`, `g`, `i`, `n` — that's `\begin` - `{`, `V`, `e`, `r`, `b`, `a`, `t`, `i`, `m`, `}` — that's `{Verbatim}` - `[`, `c`, `o`, `m`, `m`, `a`, `n`, `d`, `c`, `h`, `a`, `r`, `s`, `=` — that's `[commandchars=` - `\`, `\`, `\`, `{`, `\`, `}`, `]` — that's `\\\{\}` So the string is: `\begin{Verbatim}[commandchars=\\\{\}]` Now the replace pattern in the code is: `r'\begin{Verbatim}[commandchars=\\\{\}]'` As a raw string, this is: `\begin{Verbatim}[commandchars=\\\{\}]` Wait, let me count the backslashes in the raw string: - `\b` → `\b` (backslash + b) - `\e` → `\e` (backslash + e) - `\begin{Verbatim}[commandchars=` → literal text - `\\` → `\\` (two backslashes in the raw string = two backslash characters) - `\{\}` → `\{\}` (backslash + { + backslash + }) So the pattern string is: `\begin{Verbatim}[commandchars=\\\{\}]` And the target string is: `\begin{Verbatim}[commandchars=\\\{\}]` Wait, let me count the backslashes in the target string from Pygments: After `commandchars=`: `\`, `\`, `\`, `{`, `\`, `}` That's 3 backslashes, then `{`, then backslash, then `}`. But the pattern has: After `commandchars=`: `\`, `\`, `{`, `\`, `}` That's 2 backslashes, then `{`, then backslash, then `}`. They don't match! The Pygments output has 3 backslashes before `{` while the pattern expects 2. Wait, let me look at the Pygments source for the LaTeX formatter to understand the commandchars. The Verbatim environment has `commandchars=\\\{\}` which means the command characters are `\`, `{`, and `}`. In LaTeX, `\\` is a line break, `\{` is an escaped brace, and `\}` is an escaped brace. But for the Verbatim environment, the commandchars are set to: backslash, open brace, close brace. The backslash is the escape character, so to specify backslash as a command character, you need to escape it: `\\`. Same for `\{` and `\}`. So `commandchars=\\\{\}` means: backslash (escaped as `\\`), open brace (escaped as `\{`), close brace (escaped as `\}`). Now, the Pygments string representation: in Python, `\\` is a single backslash character. So the actual string from Pygments has: - `\begin{Verbatim}[commandchars=\` - then `\`, `\`, `\`, `{`, `\`, `}`, `]` So that's: `\begin{Verbatim}[commandchars=\\\{\}]` And the pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'` is: - `\begin{Verbatim}[commandchars=\` - `\\` (two backslash characters from `\\` in the raw string) - `\{` (backslash + open brace) - `\}` (backslash + close brace) - `]` So the pattern is: `\begin{Verbatim}[commandchars=\\\{\}]` Wait, that's exactly 2 backslashes before `{`, while the target has 3 backslashes. That doesn't match! Let me look more carefully at the Pygments output. Let me count from the character list: ``` '\\', 'b', 'e', 'g', 'i', 'n', '{', 'V', 'e', 'r', 'b', 'a', 't', 'i', 'm', '}', '[', 'c', 'o', 'm', 'm', 'a', 'n', 'd', 'c', 'h', 'a', 'r', 's', '=', '\\', '\\', '\\', '{', '\\', '}', ']' ``` After `=`: `\`, `\`, `\`, `{`, `\`, `}` That's three backslash characters, then `{`, then backslash, then `}`. So the actual string has `\\\{\}` (3 backslashes + { + backslash + }), but the pattern expects `\\\{\}` (2 backslashes + { + backslash + }). This is confusing. Let me check what Pygments version is being used and then look at the LaTeX formatter. Actually wait, maybe the Pygments output has changed at some point. Let me check the Pygments version.

OK, Pygments 2.18.0. Let me check how the LaTeX formatter formats the Verbatim environment. The key question is whether the format has changed, making the replace pattern no longer match. But wait, the user reports this as a bug, so the replace must be working in production. Let me re-examine. Actually, looking back at the character list, I see: ``` '\\', 'b', 'e', 'g', 'i', 'n', '{', 'V', 'e', 'r', 'b', 'a', 't', 'i', 'm', '}', '[', 'c', 'o', 'm', 'm', 'a', 'n', 'd', 'c', 'h', 'a', 'r', 's', '=', '\\', '\\', '\\', '{', '\\', '}', ']' ``` Hmm wait, let me reconsider. In Python, the string `'\\'` is a single backslash character. So the Python repr `'\\\\'` would be two backslash characters. Let me just look at the actual printed output. The Pygments output is (from my first test): ``` '\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n...' ``` In Python repr: - `\\\\` → `\\` in actual string (two backslash chars) - Wait no. Python repr `\\` means a single backslash character. So `\\\\` means two backslash characters. Let me decode: `\\begin{Verbatim}[commandchars=\\\\\\{\\}]` - `\\` → `\` (single backslash) - `begin` → `begin` - `{Verbatim}[commandchars=` - `\\\\` → `\\` (two backslashes) - `\\` → `\` (one backslash) - `{` → `{` - `\\` → `\` (one backslash) - `}` → `}` So the actual string is: `\begin{Verbatim}[commandchars=\\\{\}]` And the pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'`: - `\begin{Verbatim}[commandchars=` - `\\` → `\\` (two backslash chars) - `\{` → `\{` (backslash + open brace) - `\}` → `\}` (backslash + close brace) - `]` So the pattern is: `\begin{Verbatim}[commandchars=\\\{\}]` And the target is: `\begin{Verbatim}[commandchars=\\\{\}]` Wait, they're the same! Let me count: - After `commandchars=`: - Pattern: `\`, `\`, `{`, `\`, `}` — 2 backslashes + { + backslash + } - Target: `\`, `\`, `\`, `{`, `\`, `}` — 3 backslashes + { + backslash + } Hmm, they're different. Let me look at the Python repr again more carefully. `'\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n...'` Breaking this down carefully: - `'` - start of string - `\\` - this is one backslash character - `begin` - literal text - `{Verbatim}[commandchars=` - `\\\\` - this is two backslash characters - `\\` - this is one backslash character - `{` - literal - `\\` - one backslash character - `}` - literal - `]` - literal So the sequence after `commandchars=` is: `\`, `\`, `\`, `{`, `\`, `}` — 3 backslashes, `{`, backslash, `}`. But the pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'`: - `\begin{Verbatim}[commandchars=` - `\\` - two backslash characters (from `\\` in raw string) - `\{` - backslash + `{` - `\}` - backslash + `}` - `]` So pattern: `\begin{Verbatim}[commandchars=\\\{\}]` — 2 backslashes, `{`, backslash, `}`. These don't match! So the replace should NOT work. But the user reports it works (with the space issue). Let me check if maybe the `hlescape` function transforms the string somehow... Actually wait, I ran the test without `hlescape`. Let me check what `hlescape` does to this specific string.

The replace doesn't work! Let me check what the actual string contains vs what the pattern is. From the Pygments output: The actual string has: `\begin{Verbatim}[commandchars=\\\{\}]` But the pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'` yields: `\begin{Verbatim}[commandchars=\\\{\}]` Wait, let me decode both carefully. The Python repr of the result is: ``` '\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n...' ``` Let me parse this character by character: 1. `\\` → single `\` (backslash) 2. `b` → `b` 3. `e` → `e` 4. `g` → `g` 5. `i` → `i` 6. `n` → `n` 7. `{` → `{` 8. `V` → `V` 9. ... `}` → `}` 10. `[` → `[` 11. `c` through `=` → `commandchars=` 12. `\\\\` → `\\` (two backslash characters) 13. `\\` → `\` (one backslash character) 14. `{` → `{` 15. `\\` → `\` (one backslash character) 16. `}` → `}` 17. `]` → `]` So the actual string is: `\begin{Verbatim}[commandchars=\\\{\}]` (3 backslashes, then `{`, then backslash, then `}`) The pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'`: 1. `\b` → `\b` (backslash + b, raw string) 2. ... After `commandchars=`: - `\\` → `\\` (two backslash characters, from `\\` in raw string) - `\{` → `\{` (backslash + `{`) - `\}` → `\}` (backslash + `}`) So pattern is: `\begin{Verbatim}[commandchars=\\\{\}]` (2 backslashes, then `{`, then backslash, then `}`) These don't match! The target has 3 backslashes before `{`, the pattern has 2. But wait, the code has been using this replace and presumably it works in production. Maybe the Pygments version in CI is different? Let me check what Pygments version the tests expect. Actually, maybe the issue is that the `commandchars` value in the Pygments LaTeX formatter has changed between versions. Let me check the Pygments source. Actually, let me look at this differently. Let me check if maybe the replace pattern should be different, or if the Pygments version used in dev is different. Let me check the actual content of the string without the repr confusion:

OK so the actual string printed is: ``` \begin{Verbatim}[commandchars=\\\{\}] ``` And the Python repr of the first 45 characters is: ``` '\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n\\PYG{k}' ``` Let me decode the repr: - `\\` → `\` - `begin{Verbatim}[commandchars=` - `\\\\` → `\\` - `\\` → `\` - `{` → `{` - `\\` → `\` - `}` → `}` So the actual string is: `\begin{Verbatim}[commandchars=\\\{\}]` And the pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'`: - `\begin{Verbatim}[commandchars=` - `\\` → `\\` (two backslash characters) - `\{` → `\{` - `\}` → `\}` - `]` → `]` So the pattern is: `\begin{Verbatim}[commandchars=\\\{\}]` But the actual string has `\\\{\}` (3 backslash chars then `{` then backslash then `}`), while the pattern has `\\{\}` (2 backslash chars then `{` then backslash then `}`). Hmm, but let me look at the printed output more carefully. The printed output shows: ``` \begin{Verbatim}[commandchars=\\\{\}] ``` Let me convert this: when we print `\`, it shows as `\`. So: - `\begin{Verbatim}[commandchars=\` → literal text - `\\` → `\\` in print, which is 2 backslash characters - `\{\}` → `\{\}` in print - `]` → `]` Wait, but the actual string has the backslashes. Let me think about this differently. From the Python repr: `'\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n\\PYG{k}'` The repr uses `\\` to represent a single backslash character in the string. So: - `\\begin` → `\begin` (1 backslash + "begin") - `{Verbatim}[commandchars=` - `\\\\` → `\\` (2 backslash characters) - `\\` → `\` (1 backslash character) - `{` → `{` - `\\` → `\` (1 backslash character) - `}` → `}` - `]` → `]` So the actual string is: `\begin{Verbatim}[commandchars=\\\{\}]` That's: backslash + "begin" + "{Verbatim}[commandchars=" + backslash + backslash + backslash + "{" + backslash + "}" + "]" 3 backslashes before `{`. And the pattern `r'\begin{Verbatim}[commandchars=\\\{\}]'` (from the source code): In a raw string, `\` is just `\`. So: - `\begin{Verbatim}[commandchars=` - `\\` → two backslash characters (since raw string treats `\\` as two backslashes) - `\{` → backslash + `{` - `\}` → backslash + `}` - `]` So pattern is: backslash + "begin" + "{Verbatim}[commandchars=" + backslash + backslash + "{" + backslash + "}" + "]" 2 backslashes before `{`. These are different! The target has 3 backslashes, the pattern has 2. So the replace would NOT work. But the user reports that the feature works (they get syntax highlighting in the output), just with extra spaces. So somehow the replace must be working. Let me check if there's something else going on. Wait, let me check the Pygments source code for the LaTeX formatter. Maybe the commandchars value depends on the version. Actually, let me look at the Pygments LatexFormatter source to see what commandchars it uses.

Let me check the Pygments LaTeX formatter source to understand the commandchars format.

Let me look at the specific line that writes the commandchars: