Unconverted \textit{} commands in BNF grammar blocks

[lefticus]

Problem

BNF grammar blocks contain unconverted \textit{} LaTeX commands, reducing readability of grammar productions. The content is preserved (no data loss), but the formatting artifact makes the output less clean.

Affected Files

43 instances across 8 files:

• diagnostics.md: 1
• time.md: 6
• ranges.md: 3
• utilities.md: 25
• containers.md: 5
• compatibility.md: 1
• thread.md: 1
• input.md: 1

Examples

diagnostics.md (line 1685):

``` bnf
\textit{stacktrace-entry-format-spec}
    fill-and-alignₒₚₜ widthₒₚₜ

**Expected:**
```markdown
``` bnf
stacktrace-entry-format-spec
    fill-and-alignₒₚₜ widthₒₚₜ

**time.md (lines 7400, 7405, 7412, 7417, 7422, 7427):**
```markdown
``` bnf
\textit{chrono-format-spec}
    fill-and-alignₒₚₜ widthₒₚₜ precisionₒₚₜ 'L'ₒₚₜ chrono-specsₒₚₜ

**Expected:**
```markdown
``` bnf
chrono-format-spec
    fill-and-alignₒₚₜ widthₒₚₜ precisionₒₚₜ 'L'ₒₚₜ chrono-specsₒₚₜ

## Root Cause

1. LaTeX source uses `\fmtnontermdef{...}` for BNF non-terminal definitions
2. `simplified_macros.tex` converts this to `\textit{...}` (line 182)
3. `cpp-grammar.lua` filter does NOT handle `\textit{}` commands
4. Result: `\textit{}` wrapper appears in output

## Impact

- **Severity**: MINOR
- No data loss (content is preserved)
- Purely a presentation/readability issue
- Does not affect functionality of the specification

## Proposed Fix

Add `\textit{}` handler to `cpp-grammar.lua`:

```lua
-- Strip \textit{} wrapper in BNF blocks (from \fmtnontermdef conversion)
grammar = process_macro_with_replacement(grammar, "textit", function(content)
  return content  -- Remove wrapper, keep content
end)

Insert this after existing macro processing (around line 170).

Alternative Fix

Simpler approach - add to simplified_macros.tex:

\renewcommand{\textit}[1]{#1}  % Remove italic formatting, keep content

This would handle it globally, not just in BNF blocks.

Testing

1. Add unit test in tests/test_filters/test_grammar.py:

   def test_textit_in_bnf():
       r"""Test that \textit{} is stripped from BNF blocks"""
       latex = r"""
       \begin{ncbnf}
       \textit{format-spec}\br
           fill-and-align\opt{width}
       \end{ncbnf}
       """
       result = run_pandoc_with_filter(latex, "cpp-grammar")
       assert r"\textit{" not in result
       assert "format-spec" in result

2. Run test suite

3. Spot-check affected files after regeneration

Priority

Low - cosmetic issue only, all data is intact.

Related

Discovered during investigation of Issue #23, which reported missing/broken tables but was found to be incorrect.