verify-examples.pl: fail verification on unescaped backslash

[jay]

• Check that all backslashes in EXAMPLE are properly escaped.

eg manpage must always use \\n never \n.

This is because the manpage requires we always double blackslash to show a single backslash. Prior to this change an erroneous single backslash would pass through and compile even though it would not show correctly in the manpage.

Ref: #12588

Closes #xxxx

---

Note I also added die for failed open of input/output.

[jay]

For some reason the CI job manpage examples / verify (pull_request) -- which runs verify-examples.pl to verify the manpage examples -- isn't running on the commits in this PR.

[bagder]

Does it need this?

diff --git a/.github/workflows/man-examples.yml b/.github/workflows/man-examples.yml
index 080cb4c2d..640e3716c 100644
--- a/.github/workflows/man-examples.yml
+++ b/.github/workflows/man-examples.yml
@@ -10,16 +10,18 @@ on:
       - master
       - '*/ci'
     paths:
       - 'docs/libcurl/curl_*.3'
       - 'docs/libcurl/opts/*.3'
+      - '.github/scripts/verify-examples.pl'
   pull_request:
     branches:
       - master
     paths:
       - 'docs/libcurl/curl_*.3'
       - 'docs/libcurl/opts/*.3'
+      - '.github/scripts/verify-examples.pl'
 
 jobs:
   verify:
     runs-on: ubuntu-latest
     steps:

[jay]

Does it need this?

oh maybe. let's find out...

[bagder]

How about this take?

diff --git a/.github/scripts/verify-examples.pl b/.github/scripts/verify-examples.pl
index 8c8fed11b..4b4ff5810 100755
--- a/.github/scripts/verify-examples.pl
+++ b/.github/scripts/verify-examples.pl
@@ -73,10 +73,11 @@ sub extract {
                 print STDERR
                   "Error while processing file $f line $iline:\n$_" .
                   "Error: Single backslashes \\ are not properly shown in " .
                   "manpage EXAMPLE output unless they are escaped \\\\.\n";
                 $fail = 1;
+                $error++;
                 last;
             }
             # two backslashes become one
             $_ =~ s/\\\\/\\/g;
             print O $_;
@@ -95,10 +96,7 @@ for my $m (@files) {
     my $out = extract($m);
     if($out) {
       $error |= testcompile($m);
       $error |= checksrc($m);
     }
-    else {
-      $error = 1;
-    }
 }
 exit $error;