Error handling: Better reporting of nest-related errors

Track `$what' which is a kind of example for the error message.
Use it in error messages.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/generate b/generate
index 49038dfbe0ca5a57ca69221eb9f38f2f5b1fc6ef..209a1f3e6a1f19f04593cf46ff60bab84172d23e 100755 (executable)
--- a/generate
+++ b/generate
@@ -218,14 +218,14 @@ sub process_input_mk ($$$$) {
     my @nest = (['']);
 
     my $push_nest = sub {
-       my ($nk, $nndbl) = @_;
-       unshift @nest, [ $nk, $ddbl ];
+       my ($nk, $nndbl, $what) = @_;
+       unshift @nest, [ $nk, $ddbl, $what, $. ];
        $ddbl = $nndbl;
     };
     my $pop_nest = sub {
        my ($nk) = @_;
-       die unless $nest[0][0] eq $nk;
-       # ^ xxx need better message
+       err "unexpectedly closed $nk in middle of $nest[0][0] ($nest[0][2])"
+           unless $nest[0][0] eq $nk;
        $ddbl = (shift @nest)[1];
     };
 
@@ -282,7 +282,7 @@ sub process_input_mk ($$$$) {
            elsif (s{^\$\{}{}) {
                err 'macro invocation cannot be re-$-doubled' if $ddbl;
                od '${eval ${call ';
-               $push_nest->('Eval',1);
+               $push_nest->('Eval',1, '&${...}');
            } elsif (s{^([~^]?)(?=[ \t])}{}) {
                my $prefix = $pfxmap{$1} // die "internal error ($1?)";
                my $after='';
@@ -314,7 +314,8 @@ sub process_input_mk ($$$$) {
            }
        }
     }
-    die "unclosed $nest[0][0]" if $nest[0][0];
+    die "subdirmk: $f:$nest[0][3]: unclosed $nest[0][0] ($nest[0][2])\n"
+       if $nest[0][0];
     $input->error and die "read $f: $!\n";
     close $input or die "close $f: $!\n";
 }