libast & ksh: cleanup: remove unused errorctx() function

In version 93s+ 2007-03-25, AT&T added errorctx(), intending that
it replace the errorpush() and errorpop() macros used in ksh to
push and pop error contexts (this is the mechanism that shows a
call stack of functions/commands in ksh error messages).

Whereas errorpush()/errorpop() only pushes/pops a part of the
Error_info_t struct (the part that is Error_context_t), errorctx()
saves and restores the entire Error_info_t struct. This approach
looks incompatible with existing ksh practice.

After adding errorctx(), AT&T never used it. It just sat there
until they abandoned ksh, never being changed or developed. If any
attempt was made to transition to it, it must not have worked.

Meanwhile, the existing mechanism works well and is time-tested, so
it's time to delete yet another forgotten-about AT&T experiment.

src/cmd/ksh93/Mamfile,
src/lib/libast/include/error.h,
src/lib/libcmd/cmd.h:
- Remove ERROR_CONTEXT_T definition that determined the type of the
  error_info.context pointer (Error_context_t* in the old and now
  the only mechanism, Error_info_t* in the new experiment).
- Remove ERROR_FREE, ERROR_POP, ERROR_PUSH and (unused) ERROR_SET
  definitions for errorctx().
- Transfer ERROR_CALLBACK (originally an alias for ERROR_SET) from
  cmd.h to error.h so we have related definitions in one place.

src/lib/libast/misc/error.c:
- context(): Remove use of ERROR_PUSH macro.
- Remove the errorctx() function.

Author: McDutchie

src/cmd/ksh93/Mamfile

@@ -1009,7 +1009,7 @@ make install virtual
 	note * Set common compiler invocation arguments
 	note *
 
-	setv compile %{CC} %{mam_cc_FLAGS} %{CCFLAGS} %{mam_cc_NOSTRICTALIASING} %{DEBUG+-DDEBUG=%{DEBUG}} -DSH_DICT=%{SH_DICT} %{SH_CMDLIB_DIR+-DSH_CMDLIB_DIR=%{SH_CMDLIB_DIR}} -I. -Iinclude -I%{INCLUDE_AST} -D_API_ast=20100309 -DERROR_CONTEXT_T=Error_context_t -c
+	setv compile %{CC} %{mam_cc_FLAGS} %{CCFLAGS} %{mam_cc_NOSTRICTALIASING} %{DEBUG+-DDEBUG=%{DEBUG}} -DSH_DICT=%{SH_DICT} %{SH_CMDLIB_DIR+-DSH_CMDLIB_DIR=%{SH_CMDLIB_DIR}} -I. -Iinclude -I%{INCLUDE_AST} -D_API_ast=20100309 -c
 
 	note *
 	note * Build *_dyn.o object files for dynamic library

src/lib/libast/include/error.h

@@ -31,7 +31,7 @@
 #include <option.h>
 #include <errno.h>
 
-#define ERROR_VERSION	20230222L
+#define ERROR_VERSION	20251007L
 
 #if !defined(errno) && defined(__DYNAMIC__)
 #define errno		__DYNAMIC__(errno)
@@ -75,35 +75,25 @@
 #define ERROR_SILENT		0x0002	/* context is silent		*/
 #define ERROR_NOTIFY		0x0004	/* main(-sig,0,ctx) on signal	*/
 
-#define ERROR_FREE		0x0010	/* free context on pop		*/
-#define ERROR_POP		0x0020	/* pop context			*/
-#define ERROR_PUSH		0x0040	/* push context			*/
-#define ERROR_SET		0x0080	/* set context			*/
+/* for libcmd */
+#define ERROR_CALLBACK		0x0080	/* ERROR_NOTIFY main() callback	*/
 
 #ifdef ECONNRESET
 #define ERROR_PIPE(e)		((e)==EPIPE||(e)==ECONNRESET||(e)==EIO)
 #else
 #define ERROR_PIPE(e)		((e)==EPIPE||(e)==EIO)
 #endif
 
-/*
- * errorpush()/errorpop() are obsolete -- use errorctx() instead
- */
-
-#ifndef ERROR_CONTEXT_T
-#define ERROR_CONTEXT_T		Error_info_t
-#endif
-
 #define ERROR_CONTEXT_BASE	((Error_context_t*)&error_info.context)
 
-#define errorpush(p,f)	(*(p)=*ERROR_CONTEXT_BASE,*ERROR_CONTEXT_BASE=error_info.empty,error_info.context=(Error_context_t*)(p),error_info.flags=(f))
+#define errorpush(p,f)	(*(p)=*ERROR_CONTEXT_BASE,*ERROR_CONTEXT_BASE=error_info.empty,error_info.context=(p),error_info.flags=(f))
 #define errorpop(p)	(*ERROR_CONTEXT_BASE=*(p))
 
 typedef struct Error_info_s Error_info_t;
 typedef struct Error_context_s Error_context_t;
 
 #define ERROR_CONTEXT \
-	ERROR_CONTEXT_T* context;	/* prev context stack element	*/ \
+	Error_context_t* context;	/* prev context stack element	*/ \
 	int	errors;			/* >= ERROR_ERROR count		*/ \
 	int	flags;			/* context flags		*/ \
 	int	line;			/* input|output line number	*/ \
@@ -203,6 +193,5 @@ extern void		errorv(const char*, int, va_list);
 #ifndef errorx
 extern char*		errorx(const char*, const char*, const char*, const char*);
 #endif
-extern Error_info_t*	errorctx(Error_info_t*, int, int);
 
 #endif

src/lib/libast/misc/error.c

@@ -281,13 +281,11 @@ print(Sfio_t* sp, char* name, char* delim)
  * print error context FIFO stack
  */
 
-#define CONTEXT(f,p)	(((f)&ERROR_PUSH)?((Error_context_t*)&(p)->context->context):((Error_context_t*)(p)))
-
 static void
 context(Sfio_t* sp, Error_context_t* cp)
 {
 	if (cp->context)
-		context(sp, CONTEXT(cp->flags, cp->context));
+		context(sp, cp->context);
 	if (!(cp->flags & ERROR_SILENT))
 	{
 		if (cp->id)
@@ -432,7 +430,7 @@ errorv(const char* id, int level, va_list ap)
 			if (level && !(flags & ERROR_NOID))
 			{
 				if (error_info.context && level > 0)
-					context(stkstd, CONTEXT(error_info.flags, error_info.context));
+					context(stkstd, error_info.context);
 				if (file)
 					print(stkstd, file, (flags & ERROR_LIBRARY) ? " " : ": ");
 				if (flags & (ERROR_CATALOG|ERROR_LIBRARY))
@@ -593,46 +591,3 @@ errorv(const char* id, int level, va_list ap)
 	if (level >= ERROR_FATAL)
 		(*error_info.exit)(level - ERROR_FATAL + 1);
 }
-
-/*
- * error_info context control
- */
-
-static Error_info_t*	freecontext;
-
-Error_info_t*
-errorctx(Error_info_t* p, int op, int flags)
-{
-	if (op & ERROR_POP)
-	{
-		if (!(_error_infop_ = p->context))
-			_error_infop_ = &_error_info_;
-		if (op & ERROR_FREE)
-		{
-			p->context = freecontext;
-			freecontext = p;
-		}
-		p = _error_infop_;
-	}
-	else
-	{
-		if (!p)
-		{
-			if (p = freecontext)
-				freecontext = freecontext->context;
-			else if (!(p = newof(0, Error_info_t, 1, 0)))
-				return NULL;
-			*p = *_error_infop_;
-			p->errors = p->flags = p->line = p->warnings = 0;
-			p->catalog = p->file = 0;
-		}
-		if (op & ERROR_PUSH)
-		{
-			p->flags = flags;
-			p->context = _error_infop_;
-			_error_infop_ = p;
-		}
-		p->flags |= ERROR_PUSH;
-	}
-	return p;
-}

src/lib/libcmd/cmd.h

@@ -31,8 +31,6 @@
 
 #define cmdinit			_cmd_init
 
-#define ERROR_CALLBACK		ERROR_SET
-
 #include <cmdext.h>
 
 #if defined(CMD_BUILTIN) && !defined(CMD_STANDALONE)