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Re: [Bug] \~ can overwrite previous text.
From: |
Alejandro Colomar |
Subject: |
Re: [Bug] \~ can overwrite previous text. |
Date: |
Tue, 7 Mar 2023 02:15:09 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 |
Hi Branden,
On 3/6/23 18:46, G. Branden Robinson wrote:
> You're close but not quite there, I _think_. (Until I've root-caused
> this myself, or seen someone else's convincing demonstration, my
> conclusions must be tentative ones.)
>
> Because _ordinary_ spaces don't get squeezed, I would start at
> `distribute_space()` in src/roff/troff/env.cpp and navigate up and down
> the call stack from there.
>
> static void distribute_space(node *n, int nspaces, hunits desired_space,
> bool force_reverse_node_list = false)
Thanks! This seems to be involved. I tried a trivial fix to see if it
would work. Sadly, it has negative consequences (a regression). I'll
share so you don't lose your time in the same attempt:
diff --git a/src/roff/troff/env.cpp b/src/roff/troff/env.cpp
index 9f00284c6..0ec4e40e3 100644
--- a/src/roff/troff/env.cpp
+++ b/src/roff/troff/env.cpp
@@ -2081,11 +2081,12 @@ static node *node_list_reverse(node *n)
static void distribute_space(node *n, int nspaces, hunits desired_space,
bool force_reverse_node_list = false)
{
- if (desired_space.is_zero() || nspaces == 0)
- return;
// Positive desired space is the typical case. Negative desired space
- // is possible if we have overrun an unbreakable line. But we should
- // not get here if there are no adjustable space nodes to adjust.
+ // is possible if we have overrun an unbreakable line.
+ if (desired_space.to_units() <= 0 || nspaces == 0)
+ return;
+ // But we should not get here if there are no adjustable space nodes
+ // to adjust.
assert(nspaces > 0);
// Space cannot always be distributed evenly among all of the space
// nodes in the node list: there are limits to device resolution. We
@@ -2098,8 +2099,7 @@ static void distribute_space(node *n, int nspaces, hunits
desired_space,
static bool do_reverse_node_list = false;
if (force_reverse_node_list || do_reverse_node_list)
n = node_list_reverse(n);
- if (!force_reverse_node_list && spread_limit >= 0
- && desired_space.to_units() > 0) {
+ if (!force_reverse_node_list && spread_limit >= 0) {
hunits em = curenv->get_size();
double Ems = (double)desired_space.to_units() / nspaces
/ (em.is_zero() ? hresolution : em.to_units());
With the above patch, my bug is fixed, but the following test fails:
XFAIL: tmac/tests/e_footnotes-work-with-columns.sh
which is about <https://savannah.gnu.org/bugs/?58736>.
Now, I'm not sure if the fix correct and the old #58736 needs further
fixing, or if I should try to find a better fix that doesn't cause
regressions. I'll investigate a little bit more.
Cheers,
Alex
--
<http://www.alejandro-colomar.es/>
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