Fix many compiler warnings and remove unused variables (#191)

Most of these changes remove unused variables, functions and labels
to fix -Wunused compiler warnings. Somewhat notable changes:

src/cmd/ksh93/bltins/print.c:
- Removed the unused 'neg' variable.
  Patch from ksh2020: https://github.com/att/ast/pull/725

src/cmd/ksh93/bltins/sleep.c:
- Initialized ns to fix three -Wsometimes-uninitialized warnings.

src/cmd/ksh93/edit/{emacs,vi}.c:
- Adjust strncpy size to fix two -Wstringop-truncation warnings.

src/cmd/ksh93/include/shell.h:
- The NOT_USED macro caused many -Wunused-value warnings,
  so it has been replaced with ksh2020's macro:
  19d0620a

src/cmd/ksh93/sh/expand.c:
- Removed an unnecessary 'ap = ' since 'ap' is never read
  between stakseek and stakfreeze.

src/cmd/ksh93/edit/vi.c: refresh():
- Undef this function's 'w' macro at the end of it to stop it
  potentially interfering with future code changes.

src/cmd/ksh93/sh/nvdisc.c,
src/lib/libast/misc/magic.c,
src/lib/libast/regex/regsubexec.c,
src/lib/libast/sfio/sfpool.c,
src/lib/libast/vmalloc/vmbest.c:
- Fixed some indentation to silence -Wmisleading-indentation
  warnings.

src/lib/libast/include/ast.h:
- For clang, now only suppress hundreds of -Wparentheses warnings
  as well as a few -Wstring-plus-int warnings.
  Clang's -Wparentheses warns about things like
  	if(foo = bar())
  which assigns to foo and checks the assigned value.
  Clang wants us to change this into
  	if((foo = bar()))
  Clang's -Wstring-plus-int warns about things like
  	"string"+x
  where x is an integer, e.g. "string"+3 represents the string
  "ing". Clang wants us to change that to
  	"string"[3]
  The original versions represent a perfectly valid coding style
  that was common in the 1980s and 1990s and is not going to change
  in this historic code base. (gcc does not complain about these.)

Co-authored-by: Martijn Dekker <martijn@inlv.org>

src/cmd/ksh93/bltins/print.c

@@ -679,7 +679,6 @@ static const char *mapformat(Sffmt_t *fe)
 static int extend(Sfio_t* sp, void* v, Sffmt_t* fe)
 {
 	char*		lastchar = "";
-	register int	neg = 0;
 	Sfdouble_t	d;
 	Sfdouble_t	longmin = LDBL_LLONG_MIN;
 	Sfdouble_t	longmax = LDBL_LLONG_MAX;
@@ -884,8 +883,6 @@ static int extend(Sfio_t* sp, void* v, Sffmt_t* fe)
 				}
 				break;
 			}
-			if(neg)
-				value->ll = -value->ll;
 			fe->size = sizeof(value->ll);
 			break;
 		case 'a':

src/cmd/ksh93/bltins/sleep.c

@@ -73,6 +73,7 @@ int	b_sleep(register int argc,char *argv[],Shbltin_t *context)
 			Time_t now,ns;
 			char* pp;
 			now = TMX_NOW;
+			ns = 0;
 			if(*cp == 'P' || *cp == 'p')
 				ns = tmxdate(cp, &last, now);
 			else if(*last=='.' && shp->decomma && d==(unsigned long)d)

src/cmd/ksh93/bltins/typeset.c

@@ -72,12 +72,6 @@ static int	setall(char**, int, Dt_t*, struct tdata*);
 static void	pushname(Namval_t*,void*);
 static void(*nullscan)(Namval_t*,void*);
 
-static Namval_t *load_class(const char *name)
-{
-	errormsg(SH_DICT,ERROR_exit(1),"%s: type not loadable",name);
-	return(0);
-}
-
 /*
  * Note export and readonly are the same
  */
@@ -131,7 +125,6 @@ int    b_alias(int argc,register char *argv[],Shbltin_t *context)
 	register Dt_t *troot;
 	register int rflag=0, n;
 	struct tdata tdata;
-	Namval_t *np;
 	NOT_USED(argc);
 	memset((void*)&tdata,0,sizeof(tdata));
 	tdata.sh = context->shp;
@@ -275,8 +268,8 @@ int    b_typeset(int argc,register char *argv[],Shbltin_t *context)
 					flag |= NV_HEXFLOAT;
 				}
 				else
-				        /* n=='F' Remove possible collision with NV_UNSIGN/NV_HEXFLOAT */
-				        flag &= ~NV_HEXFLOAT;
+					/* n=='F' Remove possible collision with NV_UNSIGN/NV_HEXFLOAT */
+					flag &= ~NV_HEXFLOAT;
 				break;
 			case 'b':
 				flag |= NV_BINARY;
@@ -366,10 +359,10 @@ int    b_typeset(int argc,register char *argv[],Shbltin_t *context)
 				flag |= NV_TAGGED;
 				break;
 			case 'u':
-			        if(!isfloat)
-			        {
-				        tdata.wctname = e_toupper;
-				        flag |= NV_LTOU;
+				if(!isfloat)
+				{
+					tdata.wctname = e_toupper;
+					flag |= NV_LTOU;
 				}
 				break;
 			case 'x':

src/cmd/ksh93/edit/emacs.c

@@ -1344,7 +1344,7 @@ static void search(Emacs_t* ep,genchar *out,int direction)
 #if SHOPT_MULTIBYTE
 		ed_external(string,(char*)string);
 #endif /* SHOPT_MULTIBYTE */
-		strncpy(lstring,((char*)string)+2,SEARCHSIZE);
+		strncpy(lstring,((char*)string)+2,SEARCHSIZE-1);
 		lstring[SEARCHSIZE-1] = 0;
 		ep->prevdirection = direction;
 	}

src/cmd/ksh93/edit/vi.c

@@ -67,12 +67,10 @@
 #	define iswprint(c)	((c&~0177) || isprint(c))
 #   endif
     static int _isalph(int);
-    static int _ismetach(int);
     static int _isblank(int);
 #   undef  isblank
 #   define isblank(v)	_isblank(virtual[v])
 #   define isalph(v)	_isalph(virtual[v])
-#   define ismetach(v)	_ismetach(virtual[v])
 #else
     static genchar	_c;
 #   define gencpy(a,b)	strcpy((char*)(a),(char*)(b))
@@ -81,7 +79,6 @@
 #   define isalph(v)	((_c=virtual[v])=='_'||isalnum(_c))
 #   undef  isblank
 #   define isblank(v)	isspace(virtual[v])
-#   define ismetach(v)	ismeta(virtual[v])
 #   define digit(c)	isdigit(c)
 #   define is_print(c)	isprint(c)
 #endif	/* SHOPT_MULTIBYTE */
@@ -2098,6 +2095,7 @@ static void refresh(register Vi_t* vp, int mode)
 	cursor(vp,ncur_phys);
 	ed_flush(vp->ed);
 	return;
+#	undef	w
 }
 
 /*{	REPLACE( char, increment )
@@ -2323,7 +2321,7 @@ static int search(register Vi_t* vp,register int mode)
 		location = hist_find(shgd->hist_ptr,((char*)virtual)+1, curhline, 1, new_direction);
 	}
 	cur_virt = i;
-	strncpy(lsearch, ((char*)virtual)+1, SEARCHSIZE);
+	strncpy(lsearch, ((char*)virtual)+1, SEARCHSIZE-1);
 	lsearch[SEARCHSIZE-1] = 0;
 	if( (curhline=location.hist_command) >=0 )
 	{
@@ -2785,12 +2783,6 @@ yankeol:
     {
 	return((v&~STRIP)==0 && isspace(v));
     }
-
-    static int _ismetach(register int v)
-    {
-	return((v&~STRIP)==0 && ismeta(v));
-    }
-
 #endif	/* SHOPT_MULTIBYTE */
 
 /*

src/cmd/ksh93/features/math.sh

@@ -122,6 +122,7 @@ eval `iffe $iffeflags -c "$cc" - num $nums $iffehdrs $iffelibs 2>&$stderr`
 
 cat <<!
 #pragma prototyped
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
 
 /* : : generated by $command from $table : : */
 

src/cmd/ksh93/include/shell.h

@@ -37,8 +37,17 @@
 #   include	<nval.h>
 #endif /* _SH_PRIVATE */
 
+/*
+ * This is a macro that can be used to silence "unused parameter" warnings from the compiler for
+ * functions which need to accept parameters they do not use because they need to be compatible
+ * with an interface.
+ */
 #undef NOT_USED
-#define NOT_USED(x)	(&x,1)
+#define NOT_USED(expr)		\
+	do {			\
+		(void)(expr);	\
+	} while (0)
+
 
 /* options */
 typedef struct

src/cmd/ksh93/sh/expand.c

@@ -65,11 +65,6 @@
 #   define GLOB_AUGMENTED	0
 #endif
 
-#define GLOB_RESCAN 1
-#define globptr()	((struct glob*)membase)
-
-static struct glob	 *membase;
-
 static char *nextdir(glob_t *gp, char *dir)
 {
 	Shell_t	*shp = sh_getinterp();
@@ -143,7 +138,7 @@ static int scantree(Dt_t *tree, const char *pattern, struct argnod **arghead)
 	{
 		if(strmatch(cp=nv_name(np),pattern))
 		{
-			ap = (struct argnod*)stakseek(ARGVAL);
+			(void)stakseek(ARGVAL);
 			stakputs(cp);
 			ap = (struct argnod*)stakfreeze(1);
 			ap->argbegin = NIL(char*);

src/cmd/ksh93/sh/init.c

@@ -383,16 +383,6 @@ static void put_cdpath(register Namval_t* np,const char *val,int flags,Namfun_t
 }
 
 #ifdef _hdr_locale
-    /*
-     * This function needs to be modified to handle international
-     * error message translations
-     */
-    static char* msg_translate(const char* catalog, const char* message)
-    {
-	NOT_USED(catalog);
-	return((char*)message);
-    }
-
     /* Trap for LC_ALL, LC_CTYPE, LC_MESSAGES, LC_COLLATE and LANG */
     static void put_lang(Namval_t* np,const char *val,int flags,Namfun_t *fp)
     {
@@ -731,13 +721,6 @@ static void put_lastarg(Namval_t* np,const char *val,int flags,Namfun_t *fp)
 	np->nvenv = 0;
 }
 
-static int hasgetdisc(register Namfun_t *fp)
-{
-        while(fp && !fp->disc->getnum && !fp->disc->getval)
-                fp = fp->next;
-	return(fp!=0);
-}
-
 /*
  * store the most recent value for use in .sh.match
  * treat .sh.match as a two dimensional array
@@ -1034,7 +1017,6 @@ static const Namdisc_t SH_MATH_disc  = { 0, 0, get_math, 0, setdisc_any, create_
 	return((char*)np->nvalue.cp);
     }
     static const Namdisc_t NSPACE_disc	= {  0, 0, get_nspace };
-    static Namfun_t NSPACE_init	= {  &NSPACE_disc, 1};
 #endif /* SHOPT_NAMESPACE */
 
 #ifdef _hdr_locale

src/cmd/ksh93/sh/io.c

@@ -387,14 +387,6 @@ struct Match
 	char	*base;
 };
 
-static int matchf(void *handle, char *ptr, size_t size)
-{
-	struct Match *mp = (struct Match*)handle;
-	mp->offset += (ptr-mp->base);
-	return(1);
-}
-
-
 static struct fdsave	*filemap;
 static short		filemapsize;
 

src/cmd/ksh93/sh/jobs.c

@@ -1092,8 +1092,6 @@ int job_kill(register struct process *pw,register int sig)
 int job_hup(struct process *pw, int sig)
 {
 	struct process	*px;
-	pid_t	pid;
-	int	r;
 	NOT_USED(sig);
 	if(pw->p_pgrp == 0 || (pw->p_flag & P_DISOWN))
 		return(0);

src/cmd/ksh93/sh/nvdisc.c

@@ -947,11 +947,11 @@ int nv_clone(Namval_t *np, Namval_t *mp, int flags)
 	if(flags&NV_APPEND)
 		return(1);
 	if(mp->nvsize == size)
-	        nv_setsize(mp,nv_size(np));
+		nv_setsize(mp,nv_size(np));
 	if(mp->nvflag == flag)
-	        mp->nvflag = (np->nvflag&~(NV_MINIMAL))|(mp->nvflag&NV_MINIMAL);
-		if(nv_isattr(np,NV_EXPORT))
-			mp->nvflag |= (np->nvflag&NV_MINIMAL);
+		mp->nvflag = (np->nvflag&~(NV_MINIMAL))|(mp->nvflag&NV_MINIMAL);
+	if(nv_isattr(np,NV_EXPORT))
+		mp->nvflag |= (np->nvflag&NV_MINIMAL);
 	if(mp->nvalue.cp==val && !nv_isattr(np,NV_INTEGER))
 	{
 		if(np->nvalue.cp && np->nvalue.cp!=Empty && (flags&NV_COMVAR) && !(flags&NV_MOVE))

src/cmd/ksh93/sh/xec.c

@@ -70,7 +70,6 @@ static void	coproc_init(Shell_t*, int pipes[]);
 static void	*timeout;
 static char	nlock;
 static char	pipejob;
-static char	nopost;
 static int	restorefd;
 
 struct funenv