readd noreturn and silence "noreturn that returns" warning on MSVC

Based on commit 73758d77 (by me), in commit 117af67d629 more things got
noreturn removed on MSVC. See also ML post
"(Hugmeir) Re: [perl.git] branch blead, updated. v5.21.0-377-gdc3bf40"
This caused a measurable increase in machine code size in 117af67d629 .
In commit 73758d77 , the reason there was no increase is
Perl_magic_regdatum_set is called only through a magic vtable. Optimizing
this to noreturn is forbidden unless the struct member type specifies it
(and it obviously doesn't, since this is the magic vtable).

The other not-noreturn on MSVC function, Perl_screaminstr, has no core
usage (its only reference is in the export table) or CPAN grep usage so
therefore it is being removed. It was made fatal in commit 9e3f0d16db .

before .text section of perl521.dll on VC 2003 32b, 0xc66a3 bytes, after
0xc6453

5 files changed, 54 insertions, 102 deletions

diff --git a/embed.fnc b/embed.fnc
index 9f3539eeb0..77ceca8945 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -281,12 +281,7 @@ norx	|void	|win32_croak_not_implemented|NN const char * fname
 #endif
 #if defined(PERL_IMPLICIT_CONTEXT)
 Afnrp	|void	|croak_nocontext|NULLOK const char* pat|...
-:removing noreturn to silence a warning
-#ifdef _MSC_VER
-Afnp   |OP*    |die_nocontext  |NULLOK const char* pat|...
-#else
 Afnrp  |OP*    |die_nocontext  |NULLOK const char* pat|...
-#endif
 Afnp	|void	|deb_nocontext	|NN const char* pat|...
 Afnp	|char*	|form_nocontext	|NN const char* pat|...
 Anp	|void	|load_module_nocontext|U32 flags|NN SV* name|NULLOK SV* ver|...
@@ -343,14 +338,8 @@ Anp	|char*	|delimcpy	|NN char* to|NN const char* toend|NN const char* from \
 				|NN const char* fromend|int delim|NN I32* retlen
 : Used in op.c, perl.c
 pM	|void	|delete_eval_scope
-:removing noreturn to silence a warning
-#ifdef _MSC_VER
-Apd    |OP*    |die_sv         |NN SV *baseex
-Afpd   |OP*    |die            |NULLOK const char* pat|...
-#else
 Aprd    |OP*    |die_sv         |NN SV *baseex
 Afrpd   |OP*    |die            |NULLOK const char* pat|...
-#endif
 : Used in util.c
 pr	|void	|die_unwind	|NN SV* msv
 Ap	|void	|dounwind	|I32 cxix
@@ -850,7 +839,8 @@ p	|int	|magic_nextpack	|NN SV *sv|NN MAGIC *mg|NN SV *key
 p	|U32	|magic_regdata_cnt|NN SV* sv|NN MAGIC* mg
 p	|int	|magic_regdatum_get|NN SV* sv|NN MAGIC* mg
 :removing noreturn to silence a warning for this function resulted in no
-:change to the interpreter DLL image under VS 2003 -O1 -GL 32 bits
+:change to the interpreter DLL image under VS 2003 -O1 -GL 32 bits only because
+:this is used in a magic vtable, do not use this on conventionally called funcs
 #ifdef _MSC_VER
 p	|int	|magic_regdatum_set|NN SV* sv|NN MAGIC* mg
 #else
@@ -1322,14 +1312,6 @@ Apd	|NV	|scan_hex	|NN const char* start|STRLEN len|NN STRLEN* retlen
 Ap	|char*	|scan_num	|NN const char* s|NN YYSTYPE *lvalp
 Apd	|NV	|scan_oct	|NN const char* start|STRLEN len|NN STRLEN* retlen
 AMpd	|OP*	|op_scope	|NULLOK OP* o
-:removing noreturn to silence a warning
-#ifdef _MSC_VER
-Ap      |char*  |screaminstr    |NN SV *bigstr|NN SV *littlestr|I32 start_shift \
-                                |I32 end_shift|NN I32 *old_posp|I32 last
-#else
-Apr     |char*  |screaminstr    |NN SV *bigstr|NN SV *littlestr|I32 start_shift \
-                                |I32 end_shift|NN I32 *old_posp|I32 last
-#endif
 : Only used by perl.c/miniperl.c, but defined in caretx.c
 px	|void	|set_caret_X
 Apd	|void	|setdefout	|NN GV* gv
diff --git a/embed.h b/embed.h
index 32ef097aa7..7fddb5d229 100644
--- a/embed.h
+++ b/embed.h
@@ -117,6 +117,10 @@
 #define debstackptrs()		Perl_debstackptrs(aTHX)
 #define delimcpy		Perl_delimcpy
 #define despatch_signals()	Perl_despatch_signals(aTHX)
+#ifndef PERL_IMPLICIT_CONTEXT
+#define die			Perl_die
+#endif
+#define die_sv(a)		Perl_die_sv(aTHX_ a)
 #define do_binmode(a,b,c)	Perl_do_binmode(aTHX_ a,b,c)
 #define do_close(a,b)		Perl_do_close(aTHX_ a,b)
 #define do_gv_dump(a,b,c,d)	Perl_do_gv_dump(aTHX_ a,b,c,d)
@@ -750,16 +754,6 @@
 #if !(defined(NO_MATHOMS))
 #define sv_nounlocking(a)	Perl_sv_nounlocking(aTHX_ a)
 #endif
-#if !(defined(_MSC_VER))
-#ifndef PERL_IMPLICIT_CONTEXT
-#define die			Perl_die
-#endif
-#define die_sv(a)		Perl_die_sv(aTHX_ a)
-#define screaminstr(a,b,c,d,e,f)	Perl_screaminstr(aTHX_ a,b,c,d,e,f)
-#  if defined(PERL_IMPLICIT_CONTEXT)
-#define die_nocontext		Perl_die_nocontext
-#  endif
-#endif
 #if !defined(HAS_BZERO) && !defined(HAS_MEMSET)
 #define my_bzero		Perl_my_bzero
 #endif
@@ -805,6 +799,7 @@
 #if defined(PERL_IMPLICIT_CONTEXT)
 #define croak_nocontext		Perl_croak_nocontext
 #define deb_nocontext		Perl_deb_nocontext
+#define die_nocontext		Perl_die_nocontext
 #define form_nocontext		Perl_form_nocontext
 #define fprintf_nocontext	Perl_fprintf_nocontext
 #define load_module_nocontext	Perl_load_module_nocontext
@@ -817,9 +812,6 @@
 #define sv_setpvf_nocontext	Perl_sv_setpvf_nocontext
 #define warn_nocontext		Perl_warn_nocontext
 #define warner_nocontext	Perl_warner_nocontext
-#  if defined(_MSC_VER)
-#define die_nocontext		Perl_die_nocontext
-#  endif
 #endif
 #if defined(PERL_IN_REGCOMP_C) || defined(PERL_IN_PERL_C) || defined(PERL_IN_UTF8_C)
 #define _new_invlist_C_array(a)	Perl__new_invlist_C_array(aTHX_ a)
@@ -896,13 +888,6 @@
 #define do_spawn(a)		Perl_do_spawn(aTHX_ a)
 #define do_spawn_nowait(a)	Perl_do_spawn_nowait(aTHX_ a)
 #endif
-#if defined(_MSC_VER)
-#ifndef PERL_IMPLICIT_CONTEXT
-#define die			Perl_die
-#endif
-#define die_sv(a)		Perl_die_sv(aTHX_ a)
-#define screaminstr(a,b,c,d,e,f)	Perl_screaminstr(aTHX_ a,b,c,d,e,f)
-#endif
 #if defined(PERL_CORE) || defined(PERL_EXT)
 #define av_reify(a)		Perl_av_reify(aTHX_ a)
 #define current_re_engine()	Perl_current_re_engine(aTHX)
diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index c893a8ed2e..1e4e7b2c7f 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -383,7 +383,9 @@ well.
 
 =item *
 
-XXX
+C<screaminstr> has been removed. Although marked as public API, it is
+undocumented and has no usage in modern perl versions on CPAN Grep. Calling it
+has been fatal since 5.17.0.
 
 =back
 
diff --git a/proto.h b/proto.h
index 03a36f0656..656d6b4084 100644
--- a/proto.h
+++ b/proto.h
@@ -904,6 +904,16 @@ PERL_CALLCONV char*	Perl_delimcpy(char* to, const char* toend, const char* from,
 	assert(to); assert(toend); assert(from); assert(fromend); assert(retlen)
 
 PERL_CALLCONV void	Perl_despatch_signals(pTHX);
+PERL_CALLCONV_NO_RET OP*	Perl_die(pTHX_ const char* pat, ...)
+			__attribute__noreturn__
+			__attribute__format__null_ok__(__printf__,pTHX_1,pTHX_2);
+
+PERL_CALLCONV_NO_RET OP*	Perl_die_sv(pTHX_ SV *baseex)
+			__attribute__noreturn__
+			__attribute__nonnull__(pTHX_1);
+#define PERL_ARGS_ASSERT_DIE_SV	\
+	assert(baseex)
+
 PERL_CALLCONV_NO_RET void	Perl_die_unwind(pTHX_ SV* msv)
 			__attribute__noreturn__
 			__attribute__nonnull__(pTHX_1);
@@ -5232,16 +5242,6 @@ PERL_CALLCONV void*	Perl_my_cxt_init(pTHX_ int *index, size_t size)
 
 #endif
 #if !(defined(_MSC_VER))
-PERL_CALLCONV_NO_RET OP*	Perl_die(pTHX_ const char* pat, ...)
-			__attribute__noreturn__
-			__attribute__format__null_ok__(__printf__,pTHX_1,pTHX_2);
-
-PERL_CALLCONV_NO_RET OP*	Perl_die_sv(pTHX_ SV *baseex)
-			__attribute__noreturn__
-			__attribute__nonnull__(pTHX_1);
-#define PERL_ARGS_ASSERT_DIE_SV	\
-	assert(baseex)
-
 PERL_CALLCONV_NO_RET int	Perl_magic_regdatum_set(pTHX_ SV* sv, MAGIC* mg)
 			__attribute__noreturn__
 			__attribute__nonnull__(pTHX_1)
@@ -5249,20 +5249,6 @@ PERL_CALLCONV_NO_RET int	Perl_magic_regdatum_set(pTHX_ SV* sv, MAGIC* mg)
 #define PERL_ARGS_ASSERT_MAGIC_REGDATUM_SET	\
 	assert(sv); assert(mg)
 
-PERL_CALLCONV_NO_RET char*	Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift, I32 *old_posp, I32 last)
-			__attribute__noreturn__
-			__attribute__nonnull__(pTHX_1)
-			__attribute__nonnull__(pTHX_2)
-			__attribute__nonnull__(pTHX_5);
-#define PERL_ARGS_ASSERT_SCREAMINSTR	\
-	assert(bigstr); assert(littlestr); assert(old_posp)
-
-#  if defined(PERL_IMPLICIT_CONTEXT)
-PERL_CALLCONV_NO_RET OP*	Perl_die_nocontext(const char* pat, ...)
-			__attribute__noreturn__
-			__attribute__format__null_ok__(__printf__,1,2);
-
-#  endif
 #endif
 #if !defined(HAS_BZERO) && !defined(HAS_MEMSET)
 PERL_CALLCONV char*	Perl_my_bzero(char* loc, I32 len)
@@ -5765,6 +5751,10 @@ PERL_CALLCONV void	Perl_deb_nocontext(const char* pat, ...)
 #define PERL_ARGS_ASSERT_DEB_NOCONTEXT	\
 	assert(pat)
 
+PERL_CALLCONV_NO_RET OP*	Perl_die_nocontext(const char* pat, ...)
+			__attribute__noreturn__
+			__attribute__format__null_ok__(__printf__,1,2);
+
 PERL_CALLCONV char*	Perl_form_nocontext(const char* pat, ...)
 			__attribute__format__(__printf__,1,2)
 			__attribute__nonnull__(1);
@@ -5841,11 +5831,6 @@ PERL_CALLCONV void	Perl_warner_nocontext(U32 err, const char* pat, ...)
 #define PERL_ARGS_ASSERT_WARNER_NOCONTEXT	\
 	assert(pat)
 
-#  if defined(_MSC_VER)
-PERL_CALLCONV OP*	Perl_die_nocontext(const char* pat, ...)
-			__attribute__format__null_ok__(__printf__,1,2);
-
-#  endif
 #endif
 #if defined(PERL_IMPLICIT_SYS)
 PERL_CALLCONV PerlInterpreter*	perl_alloc_using(struct IPerlMem *ipM, struct IPerlMem *ipMS, struct IPerlMem *ipMP, struct IPerlEnv *ipE, struct IPerlStdIO *ipStd, struct IPerlLIO *ipLIO, struct IPerlDir *ipD, struct IPerlSock *ipS, struct IPerlProc *ipP)
@@ -8205,27 +8190,12 @@ PERL_CALLCONV int	Perl_do_spawn_nowait(pTHX_ char* cmd)
 
 #endif
 #if defined(_MSC_VER)
-PERL_CALLCONV OP*	Perl_die(pTHX_ const char* pat, ...)
-			__attribute__format__null_ok__(__printf__,pTHX_1,pTHX_2);
-
-PERL_CALLCONV OP*	Perl_die_sv(pTHX_ SV *baseex)
-			__attribute__nonnull__(pTHX_1);
-#define PERL_ARGS_ASSERT_DIE_SV	\
-	assert(baseex)
-
 PERL_CALLCONV int	Perl_magic_regdatum_set(pTHX_ SV* sv, MAGIC* mg)
 			__attribute__nonnull__(pTHX_1)
 			__attribute__nonnull__(pTHX_2);
 #define PERL_ARGS_ASSERT_MAGIC_REGDATUM_SET	\
 	assert(sv); assert(mg)
 
-PERL_CALLCONV char*	Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift, I32 *old_posp, I32 last)
-			__attribute__nonnull__(pTHX_1)
-			__attribute__nonnull__(pTHX_2)
-			__attribute__nonnull__(pTHX_5);
-#define PERL_ARGS_ASSERT_SCREAMINSTR	\
-	assert(bigstr); assert(littlestr); assert(old_posp)
-
 #endif
 #ifdef PERL_CORE
 #  include "pp_proto.h"
diff --git a/util.c b/util.c
index 49faf9bb13..35ab0876bb 100644
--- a/util.c
+++ b/util.c
@@ -917,23 +917,6 @@ Perl_fbm_instr(pTHX_ unsigned char *big, unsigned char *bigend, SV *littlestr, U
     }
 }
 
-char *
-Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift, I32 *old_posp, I32 last)
-{
-    PERL_ARGS_ASSERT_SCREAMINSTR;
-    PERL_UNUSED_ARG(bigstr);
-    PERL_UNUSED_ARG(littlestr);
-    PERL_UNUSED_ARG(start_shift);
-    PERL_UNUSED_ARG(end_shift);
-    PERL_UNUSED_ARG(old_posp);
-    PERL_UNUSED_ARG(last);
-
-    /* This function must only ever be called on a scalar with study magic,
-       but those do not happen any more. */
-    Perl_croak(aTHX_ "panic: screaminstr");
-    NORETURN_FUNCTION_END;
-}
-
 /*
 =for apidoc foldEQ
 
@@ -1565,6 +1548,13 @@ The function never actually returns.
 =cut
 */
 
+#ifdef _MSC_VER
+#  pragma warning( push )
+#  pragma warning( disable : 4646 ) /* warning C4646: function declared with
+    __declspec(noreturn) has non-void return type */
+#  pragma warning( disable : 4645 ) /* warning C4645: function declared with
+__declspec(noreturn) has a return statement */
+#endif
 OP *
 Perl_die_sv(pTHX_ SV *baseex)
 {
@@ -1573,6 +1563,9 @@ Perl_die_sv(pTHX_ SV *baseex)
     assert(0); /* NOTREACHED */
     NORETURN_FUNCTION_END;
 }
+#ifdef _MSC_VER
+#  pragma warning( pop )
+#endif
 
 /*
 =for apidoc Am|OP *|die|const char *pat|...
@@ -1585,6 +1578,13 @@ The function never actually returns.
 */
 
 #if defined(PERL_IMPLICIT_CONTEXT)
+#ifdef _MSC_VER
+#  pragma warning( push )
+#  pragma warning( disable : 4646 ) /* warning C4646: function declared with
+    __declspec(noreturn) has non-void return type */
+#  pragma warning( disable : 4645 ) /* warning C4645: function declared with
+__declspec(noreturn) has a return statement */
+#endif
 OP *
 Perl_die_nocontext(const char* pat, ...)
 {
@@ -1596,8 +1596,18 @@ Perl_die_nocontext(const char* pat, ...)
     va_end(args);
     NORETURN_FUNCTION_END;
 }
+#ifdef _MSC_VER
+#  pragma warning( pop )
+#endif
 #endif /* PERL_IMPLICIT_CONTEXT */
 
+#ifdef _MSC_VER
+#  pragma warning( push )
+#  pragma warning( disable : 4646 ) /* warning C4646: function declared with
+    __declspec(noreturn) has non-void return type */
+#  pragma warning( disable : 4645 ) /* warning C4645: function declared with
+__declspec(noreturn) has a return statement */
+#endif
 OP *
 Perl_die(pTHX_ const char* pat, ...)
 {
@@ -1608,6 +1618,9 @@ Perl_die(pTHX_ const char* pat, ...)
     va_end(args);
     NORETURN_FUNCTION_END;
 }
+#ifdef _MSC_VER
+#  pragma warning( pop )
+#endif
 
 /*
 =for apidoc Am|void|croak_sv|SV *baseex