1) Const enough things to avoid warnings.

2) Cast ifdef_level to a size_t before comparing it to a ratio of size_ts.
   Ifdef_level should always be positive.
3) Complete prototype for chfont.
4) Cast some ptrdiff_ts to ints before using as a field width.
5) Avoid shadowing a local variable p with another local variable p.

usr.bin/indent/args.c

@@ -72,7 +72,7 @@ static const char rcsid[] =
 
 static void scan_profile(FILE *);
 
-char *option_source = "?";
+const char *option_source = "?";
 
 /*
  * N.B.: because of the way the table here is scanned, options whose names are
@@ -81,7 +81,7 @@ char *option_source = "?";
  * default value is the one actually assigned.
  */
 struct pro {
-    char       *p_name;		/* name, eg -bl, -cli */
+    const char *p_name;		/* name, eg -bl, -cli */
     int         p_type;		/* type (int, bool, special) */
     int         p_default;	/* the default value (if int) */
     int         p_special;	/* depends on type */
@@ -200,10 +200,10 @@ scan_profile(register FILE *f)
     }
 }
 
-char	*param_start;
+const char	*param_start;
 
 static int
-eqin(char *s1, char *s2)
+eqin(const char *s1, const char *s2)
 {
     while (*s1) {
 	if (*s1++ != *s2++)

usr.bin/indent/indent.c

@@ -63,9 +63,9 @@ static const char rcsid[] =
 
 static void bakcopy(void);
 
-char       *in_name = "Standard Input";	/* will always point to name of input
+const char *in_name = "Standard Input";	/* will always point to name of input
 					 * file */
-char       *out_name = "Standard Output";	/* will always point to name
+const char *out_name = "Standard Output";	/* will always point to name
 						 * of output file */
 char        bakfile[MAXPATHLEN] = "";
 
@@ -89,7 +89,7 @@ main(int argc, char **argv)
     int         squest;		/* when this is positive, we have seen a ?
 				 * without the matching : in a <c>?<s>:<s>
 				 * construct */
-    register char *t_ptr;	/* used for copying tokens */
+    const char *t_ptr;		/* used for copying tokens */
     int         type_code;	/* the type of token, returned by lexi */
 
     int         last_else = 0;	/* true iff last keyword was an else */
@@ -267,7 +267,7 @@ main(int argc, char **argv)
 	    ps.ind_level = ps.i_l_follow = col / ps.ind_size;
     }
     if (troff) {
-	register char *p = in_name,
+	const char *p = in_name,
 	           *beg = in_name;
 
 	while (*p)
@@ -574,7 +574,7 @@ check_type:
 		e_code += strlen(e_code);
 	    }
 	    else {
-		char       *res = token;
+		const char *res = token;
 
 		if (ps.in_decl && !ps.block_init) {	/* if this is a unary op
 							 * in a declaration, we
@@ -600,7 +600,7 @@ check_type:
 	    if (ps.want_blank)
 		*e_code++ = ' ';
 	    {
-		char       *res = token;
+		const char *res = token;
 
 		if (troff)
 		    switch (token[0]) {
@@ -1077,7 +1077,7 @@ check_type:
 		    while ((c = getc(input)) == '\n');
 		    ungetc(c, input);
 		}
-		if (ifdef_level < sizeof state_stack / sizeof state_stack[0]) {
+		if ((size_t)ifdef_level < sizeof(state_stack)/sizeof(state_stack[0])) {
 		    match_state[ifdef_level].tos = -1;
 		    state_stack[ifdef_level++] = ps;
 		}
@@ -1143,7 +1143,7 @@ bakcopy(void)
     int         n,
                 bakchn;
     char        buff[8 * 1024];
-    register char *p;
+    const char *p;
 
     /* construct file name .Bfile */
     for (p = in_name; *p; p++);	/* skip to end of string */

usr.bin/indent/indent.h

@@ -33,13 +33,13 @@ int	compute_code_target(void);
 int	compute_label_target(void);
 int	count_spaces(int, char *);
 int	lexi(void);
-void	diag2(int, char *);
-void	diag3(int, char *, int);
-void	diag4(int, char *, int, int);
+void	diag2(int, const char *);
+void	diag3(int, const char *, int);
+void	diag4(int, const char *, int, int);
 void	dump_line(void);
 void	fill_buffer(void);
 void	parse(int);
-void	parsefont(struct fstate *, char *);
+void	parsefont(struct fstate *, const char *);
 void	pr_comment(void);
 void	set_defaults(void);
 void	set_option(char *);

usr.bin/indent/indent_globs.h

@@ -199,7 +199,7 @@ struct fstate {
     char        size;
     int         allcaps:1;
 };
-char       *chfont();
+char       *chfont(struct fstate *, struct fstate *, char *);
 
 struct fstate
             keywordf,		/* keyword font */

usr.bin/indent/io.c

@@ -126,9 +126,9 @@ dump_line(void)
 		    s++;
 		if (s < e_lab)
 		    fprintf(output, s[0]=='/' && s[1]=='*' ? "\t%.*s" : "\t/* %.*s */",
-			    e_lab - s, s);
+			    (int)(e_lab - s), s);
 	    }
-	    else fprintf(output, "%.*s", e_lab - s_lab, s_lab);
+	    else fprintf(output, "%.*s", (int)(e_lab - s_lab), s_lab);
 	    cur_col = count_spaces(cur_col, s_lab);
 	}
 	else
@@ -539,7 +539,7 @@ count_spaces(int current, char *buffer)
 int	found_err;
 
 void
-diag4(int level, char *msg, int a, int b)
+diag4(int level, const char *msg, int a, int b)
 {
     if (level)
 	found_err = 1;
@@ -556,7 +556,7 @@ diag4(int level, char *msg, int a, int b)
 }
 
 void
-diag3(int level, char *msg, int a)
+diag3(int level, const char *msg, int a)
 {
     if (level)
 	found_err = 1;
@@ -573,7 +573,7 @@ diag3(int level, char *msg, int a)
 }
 
 void
-diag2(int level, char *msg)
+diag2(int level, const char *msg)
 {
     if (level)
 	found_err = 1;
@@ -627,9 +627,9 @@ chfont(struct fstate *of, struct fstate *nf, char *s)
 }
 
 void
-parsefont(struct fstate *f, char *s0)
+parsefont(struct fstate *f, const char *s0)
 {
-    register char *s = s0;
+    const char *s = s0;
     int         sizedelta = 0;
 
     bzero(f, sizeof *f);

usr.bin/indent/lexi.c

@@ -53,6 +53,7 @@ static const char rcsid[] =
 #include <string.h>
 #include "indent_globs.h"
 #include "indent_codes.h"
+#include "indent.h"
 
 #define alphanum 1
 #define opchar 3
@@ -60,7 +61,7 @@ static const char rcsid[] =
 void fill_buffer(void);
 
 struct templ {
-    char       *rwd;
+    const char *rwd;
     int         rwcode;
 };
 
@@ -149,7 +150,7 @@ lexi(void)
 	/*
 	 * we have a character or number
 	 */
-	register char *j;	/* used for searching thru list of
+	const char *j;		/* used for searching thru list of
 				 *
 				 * reserved words */
 	register struct templ *p;
@@ -249,15 +250,15 @@ lexi(void)
 	 * This loop will check if the token is a keyword.
 	 */
 	for (p = specials; (j = p->rwd) != 0; p++) {
-	    register char *p = s_token;	/* point at scanned token */
-	    if (*j++ != *p++ || *j++ != *p++)
+	    const char *q = s_token;	/* point at scanned token */
+	    if (*j++ != *q++ || *j++ != *q++)
 		continue;	/* This test depends on the fact that
 				 * identifiers are always at least 1 character
 				 * long (ie. the first two bytes of the
 				 * identifier are always meaningful) */
-	    if (p[-1] == 0)
+	    if (q[-1] == 0)
 		break;		/* If its a one-character identifier */
-	    while (*p++ == *j)
+	    while (*q++ == *j)
 		if (*j++ == 0)
 		    goto found_keyword;	/* I wish that C had a multi-level
 					 * break... */