LaTeX reader: fix bug parsing macro arguments.

If `\cL` is defined as `\mathcal{L}`, and `\til` as `\tilde{#1}`,
then `\til\cL` should expand to `\tilde{\mathcal{L}}`, but pandoc
was expanding it to `\tilde\mathcal{L}`.  This is fixed by
parsing the arguments in "verbatim mode" when the macro expands
arguments at the point of use.

Closes #6796.

1 files changed, 16 insertions, 0 deletions

diff --git a/test/command/6796.md b/test/command/6796.md
new file mode 100644
index 000000000..f51205a81
--- /dev/null
+++ b/test/command/6796.md
@@ -0,0 +1,16 @@
+```
+% pandoc -f latex -t markdown
+\newcommand{\cL}{\mathcal{L}}
+\newcommand{\til}[1]{\tilde{#1}}
+
+$$\til\cL$$
+
+\newcommand{\mc}[1]{\mathcal{#1}}
+\newcommand{\dL}{\mc{L}}
+
+$$\til\dL$$
+^D
+$$\tilde{\mathcal{L}}$$
+
+$$\tilde{\mathcal{L}}$$
+```