caller has mangled file path for "./" but not ".\"

[p5pRT]

Migrated from rt.perl.org#133396 (status was 'new')

Searchable as RT133396$

[p5pRT]

From @bulk88

Created by @bulk88

Continuation of no responses
https://www.nntp.perl.org/group/perl.perl5.porters/2018/07/msg251582.html

-----------------------------------------------
C​:\perl528\srcnew>perl -e"@​INC = ('.\lib'); require Cwd;"
b4 .\lib/Cwd.pm at .\lib/XSLoader.pm line 42.
af .\lib at .\lib/XSLoader.pm line 44.
-----------------------------------------------
-----------------------------------------------
C​:\perl528\srcnew>perl -e"@​INC = ('./lib'); require Cwd;"
b4 lib/Cwd.pm at lib/XSLoader.pm line 42.
af lib at lib/XSLoader.pm line 44.
bad DY at lib/XSLoader.pm line 117.
Compilation failed in require at -e line 1.
-----------------------------------------------
Why did the "./" disappear from caller() but ".\" does not in how
caller/require works?

*********new text below***********

This commit and bug ticket last touched the "./" removal code
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=66942

commit
https://perl5.git.perl.org/perl.git/commit/e63be7465b2d564165a64209685cfd7026a2005b
but the code really dates to commit
33b7830#diff-1809087843b30c07d241e424dbbb3900R831
"perl 3.0 patch #24 patch #19, continued" "Wed Aug 8 13​:04​:39 1990",
change line " * patch19​: . is now explicitly in @​INC (and last)". The
stripping of the "./" causes XSLoader to thunk into full DynaLoader
unnecessarily.

Perl Info

---
Flags:
                    category=core
                    severity=low
---
Site configuration information for perl 5.27.9:

Configured by Administrator at Tue Jan 30 20:34:30 2018.

Summary of my perl5 (revision 5 version 27 subversion 9) configuration:

                  Platform:
                    osname=MSWin32
                    osvers=5.2.3790
                    archname=MSWin32-x86-multi-thread
                    uname=''
                    config_args='undef'
                    hint=recommended
                    useposix=true
                    d_sigaction=undef
                    useithreads=define
                    usemultiplicity=define
                    use64bitint=undef
                    use64bitall=undef
                    uselongdouble=undef
                    usemymalloc=n
                    default_inc_excludes_dot=define
                    bincompat5005=undef
                  Compiler:
                    cc='cl'
                    ccflags ='-nologo -GF -W3 -O1 -MD -Zi -DNDEBUG -GL
-DWIN32
-D_CONSOLE -DNO_STRICT -D_CRT_SECURE_NO_DEPRECATE
-D_CRT_NONSTDC_NO_DEPRECATE  -DPERL_TEXTMODE_SCRIPTS
-DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DWIN32_NO_REGISTRY'
                    optimize='-O1 -MD -Zi -DNDEBUG -GL'
                    cppflags='-DWIN32'
                    ccversion='15.00.30729.01'
                    gccversion=''
                    gccosandvers=''
                    intsize=4
                    longsize=4
                    ptrsize=4
                    doublesize=8
                    byteorder=1234
                    doublekind=3
                    d_longlong=undef
                    longlongsize=8
                    d_longdbl=define
                    longdblsize=8
                    longdblkind=0
                    ivtype='long'
                    ivsize=4
                    nvtype='double'
                    nvsize=8
                    Off_t='__int64'
                    lseeksize=8
                    alignbytes=8
                    prototype=define
                  Linker and Libraries:
                    ld='link'
                    ldflags ='-nologo -nodefaultlib -debug -opt:ref,icf 
-ltcg
-libpath:"c:\perl\lib\CORE"        -machine:x86'
                    libpth="C:\Program Files (x86)\Microsoft Visual Studio
9.0\VC\lib"
                    libs=oldnames.lib kernel32.lib user32.lib gdi32.lib
winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib
netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib version.lib
odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
                    perllibs=oldnames.lib kernel32.lib user32.lib gdi32.lib
winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib
netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib version.lib
odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
                    libc=msvcrt.lib
                    so=dll
                    useshrplib=true
                    libperl=perl527.lib
                    gnulibc_version=''
                  Dynamic Linking:
                    dlsrc=dl_win32.xs
                    dlext=dll
                    d_dlsymun=undef
                    ccdlflags=' '
                    cccdlflags=' '
                    lddlflags='-dll -nologo -nodefaultlib -debug 
-opt:ref,icf
-ltcg
                    -libpath:"c:\perl\lib\CORE"        -machine:x86'


---
@INC for perl 5.27.9:
                    lib
                    C:/p527/srcnew/lib

---
Environment for perl 5.27.9:
                    CYGWIN=tty
                    HOME (unset)
                    LANG (unset)
                    LANGUAGE (unset)
                    LD_LIBRARY_PATH=/usr/lib/x86:/usr/X11R6/lib
                    LOGDIR (unset)
                    PATH=C:\WINDOWS\system32;C:\Program Files 
(x86)\Microsoft
Visual
Studio 9.0\VC\BIN;C:\Program Files\Microsoft
SDKs\Windows\v6.0A\bin;C:\Perl\bin;C:\WINDOWS;C:\Program Files
(x86)\Microsoft Visual Studio 9.0\Common7\IDE;C:\Program Files
(x86)\Git\bin;C:\sp3220\c\bin;
                    PERL_BADLANG (unset)
                    SHELL (unset)