Anonymous block shows first line not covered

[pryrt]

If I have an anonymous block (for encapsulation or other similar purposes), the first line usually shows up as uncovered, as I described here (running with Devel::Cover 1.40)

x.pl

#!perl
use 5.012; # strict, //
use warnings;

{
    my $i = 1;
    my $j = 2;
    sub get {
        $i + $j;
    }
}
get();

run:

perl -MDevel::Cover x.pl 
cover

output:

----- ------ ------ ------ ------ ------ ------ ------
File    stmt   bran   cond    sub    pod   time  total
----- ------ ------ ------ ------ ------ ------ ------
x.pl    90.9    n/a    n/a  100.0    n/a  100.0   92.8
Total   90.9    n/a    n/a  100.0    n/a  100.0   92.8
----- ------ ------ ------ ------ ------ ------ ------

The coverage report shows line 6 with two rows in the statement column, the second of which shows as uncovered.

If I change it to a do block instead, the do line shows up as uncovered, instead of the first my line.

#!perl
use 5.012; # strict, //
use warnings;

do {
    my $i = 1;
    my $j = 2;
    sub get {
        $i + $j;
    }
};
get();

and perlmonk haukex reduced it to an even simpler case { sub x {} } x(), which I have expanded slightly so you can see the line numbers for which statements show as uncovered.

{
    sub x {
        print 1;
    }
}
x();

All three of those simple scripts actually execute every statement at least once, so it really appears there's a bug in the statement coverage.

[pjcj]

Thanks very much for this report. It certainly does look like a bug. Could you please post the output of perl -V?

I suspect we'll need to look into what the optree looks like in these cases and perhaps craft something to recognise that and report correctly.

[pryrt]

Summary of my perl5 (revision 5 version 32 subversion 1) configuration:

  Platform:
    osname=MSWin32
    osvers=10.0.19042.746
    archname=MSWin32-x64-multi-thread
    uname='Win32 strawberry-perl 5.32.1.1 #1 Sun Jan 24 15:00:15 2021 x64'
    config_args='undef'
    hint=recommended
    useposix=true
    d_sigaction=undef
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=undef
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='gcc'
    ccflags =' -DWIN32 -DWIN64 -D__USE_MINGW_ANSI_STDIO -DPERL_TEXTMODE_SCRIPTS -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO -fwrapv -fno-strict-aliasing -mms-bitfields'
    optimize='-s -O2'
    cppflags='-DWIN32'
    ccversion=''
    gccversion='8.3.0'
    gccosandvers=''
    intsize=4
    longsize=4
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='long long'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='g++.exe'
    ldflags ='-s -L"C:\USR\LOCAL\APPS\STRAWBERRY\perl\lib\CORE" -L"C:\USR\LOCAL\APPS\STRAWBERRY\c\lib"'
    libpth=C:\USR\LOCAL\APPS\STRAWBERRY\c\lib C:\USR\LOCAL\APPS\STRAWBERRY\c\x86_64-w64-mingw32\lib C:\USR\LOCAL\APPS\STRAWBERRY\c\lib\gcc\x86_64-w64-mingw32\8.3.0
    libs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    perllibs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    libc=
    so=dll
    useshrplib=true
    libperl=libperl532.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs
    dlext=xs.dll
    d_dlsymun=undef
    ccdlflags=' '
    cccdlflags=' '
    lddlflags='-mdll -s -L"C:\USR\LOCAL\APPS\STRAWBERRY\perl\lib\CORE" -L"C:\USR\LOCAL\APPS\STRAWBERRY\c\lib"'

Characteristics of this binary (from libperl):
  Compile-time options:
    HAS_TIMES
    HAVE_INTERP_INTERN
    MULTIPLICITY
    PERLIO_LAYERS
    PERL_COPY_ON_WRITE
    PERL_DONT_CREATE_GVSV
    PERL_IMPLICIT_CONTEXT
    PERL_IMPLICIT_SYS
    PERL_MALLOC_WRAP
    PERL_OP_PARENT
    PERL_PRESERVE_IVUV
    USE_64_BIT_INT
    USE_ITHREADS
    USE_LARGE_FILES
    USE_LOCALE
    USE_LOCALE_COLLATE
    USE_LOCALE_CTYPE
    USE_LOCALE_NUMERIC
    USE_LOCALE_TIME
    USE_PERLIO
    USE_PERL_ATOF
  Built under MSWin32
  Compiled at Jan 24 2021 15:05:42
  @INC:
    C:/usr/local/apps/STRAWBERRY/perl/site/lib/MSWin32-x64-multi-thread
    C:/usr/local/apps/STRAWBERRY/perl/site/lib
    C:/usr/local/apps/STRAWBERRY/perl/vendor/lib
    C:/usr/local/apps/STRAWBERRY/perl/lib