Mark functions as __dead2 in order to help the LLVM static checker

understand which code paths aren't possible.

This commit eliminates 117 false positive bug reports of the form
"allocate memory; error out if pointer is NULL; use pointer".

bin/echo/echo.c

@@ -55,7 +55,7 @@ __FBSDID("$FreeBSD$");
  * Report an error and exit.
  * Use it instead of err(3) to avoid linking-in stdio.
  */
-static void
+static __dead2 void
 errexit(const char *prog, const char *reason)
 {
 	char *errstr = strerror(errno);

bin/sh/mknodes.c

@@ -103,7 +103,7 @@ static void indent(int, FILE *);
 static int nextfield(char *);
 static void skipbl(void);
 static int readline(void);
-static void error(const char *, ...) __printf0like(1, 2);
+static void error(const char *, ...) __printf0like(1, 2) __dead2;
 static char *savestr(const char *);
 
 

bin/stty/gfmt.c

@@ -44,7 +44,7 @@ __FBSDID("$FreeBSD$");
 #include "stty.h"
 #include "extern.h"
 
-static void gerr(const char *s);
+static void gerr(const char *s) __dead2;
 
 static void
 gerr(const char *s)

lib/libarchive/archive_private.h

@@ -92,7 +92,7 @@ struct archive {
 void	__archive_check_magic(struct archive *, unsigned int magic,
 	    unsigned int state, const char *func);
 
-void	__archive_errx(int retvalue, const char *msg);
+void	__archive_errx(int retvalue, const char *msg) __dead2;
 
 #define	err_combine(a,b)	((a) < (b) ? (a) : (b))
 

libexec/fingerd/fingerd.c

@@ -62,7 +62,7 @@ static const char rcsid[] =
 #include <string.h>
 #include "pathnames.h"
 
-void logerr(const char *, ...) __printflike(1, 2);
+void logerr(const char *, ...) __printflike(1, 2) __dead2;
 
 int
 main(int argc, char *argv[])

usr.bin/cpio/cpio.h

@@ -85,7 +85,7 @@ struct cpio {
 /* Name of this program; used in error reporting, initialized in main(). */
 const char *cpio_progname;
 
-void	cpio_errc(int _eval, int _code, const char *fmt, ...);
+void	cpio_errc(int _eval, int _code, const char *fmt, ...) __dead2;
 void	cpio_warnc(int _code, const char *fmt, ...);
 
 int	owner_parse(const char *, int *, int *);

usr.bin/lex/flex.skl

@@ -9,6 +9,7 @@
 #include <sys/cdefs.h>
 #else
 #define __unused
+#define __dead2
 #endif
 
 #define FLEX_SCANNER
@@ -290,7 +291,7 @@ static void yy_flex_free YY_PROTO(( void * ));
 static yy_state_type yy_get_previous_state YY_PROTO(( void ));
 static yy_state_type yy_try_NUL_trans YY_PROTO(( yy_state_type current_state ));
 static int yy_get_next_buffer YY_PROTO(( void ));
-static void yy_fatal_error YY_PROTO(( yyconst char msg[] ));
+static void yy_fatal_error YY_PROTO(( yyconst char msg[] )) __dead2;
 %*
 
 /* Done after the current pattern has been matched and before the

usr.bin/tar/bsdtar.h

@@ -103,7 +103,7 @@ struct bsdtar {
 };
 
 void	bsdtar_errc(struct bsdtar *, int _eval, int _code,
-	    const char *fmt, ...);
+	    const char *fmt, ...) __dead2;
 void	bsdtar_warnc(struct bsdtar *, int _code, const char *fmt, ...);
 void	cleanup_exclusions(struct bsdtar *);
 void	do_chdir(struct bsdtar *);

usr.bin/yacc/defs.h

@@ -309,26 +309,26 @@ char *allocate(unsigned);
 void closure(short *, int);
 void create_symbol_table(void);
 void default_action_warning(void);
-void dollar_error(int, char *, char *);
+void dollar_error(int, char *, char *) __dead2;
 void dollar_warning(int, int);
-void done(int);
-void fatal(const char *msg);
+void done(int) __dead2;
+void fatal(const char *msg) __dead2;
 void finalize_closure(void);
 void free_parser(void);
 void free_symbols(void);
 void free_symbol_table(void);
-void illegal_character(char *);
-void illegal_tag(int, char *, char *);
+void illegal_character(char *) __dead2;
+void illegal_tag(int, char *, char *) __dead2;
 void lalr(void);
 bucket *lookup(char *);
 void lr0(void);
 bucket *make_bucket(const char *);
 void make_parser(void);
-void no_grammar(void);
-void no_space(void);
-void open_error(const char *);
+void no_grammar(void) __dead2;
+void no_space(void) __dead2;
+void open_error(const char *) __dead2;
 void output(void);
-void over_unionized(char *);
+void over_unionized(char *) __dead2;
 void prec_redeclared(void);
 void reader(void);
 void reflexive_transitive_closure(unsigned *, int);
@@ -337,21 +337,21 @@ void restarted_warning(void);
 void retyped_warning(char *);
 void revalued_warning(char *);
 void set_first_derives(void);
-void syntax_error(int, char *, char *);
-void terminal_lhs(int);
-void terminal_start(char *);
-void tokenized_start(char *);
-void undefined_goal(char *);
+void syntax_error(int, char *, char *) __dead2;
+void terminal_lhs(int) __dead2;
+void terminal_start(char *) __dead2;
+void tokenized_start(char *) __dead2;
+void undefined_goal(char *) __dead2;
 void undefined_symbol_warning(char *);
-void unexpected_EOF(void);
-void unknown_rhs(int);
-void unterminated_action(int, char *, char *);
-void unterminated_comment(int, char *, char *);
-void unterminated_string(int, char *, char *);
-void unterminated_text(int, char *, char *);
-void unterminated_union(int, char *, char *);
-void untyped_lhs(void);
-void untyped_rhs(int, char *);
-void used_reserved(char *);
+void unexpected_EOF(void) __dead2;
+void unknown_rhs(int) __dead2;
+void unterminated_action(int, char *, char *) __dead2;
+void unterminated_comment(int, char *, char *) __dead2;
+void unterminated_string(int, char *, char *) __dead2;
+void unterminated_text(int, char *, char *) __dead2;
+void unterminated_union(int, char *, char *) __dead2;
+void untyped_lhs(void) __dead2;
+void untyped_rhs(int, char *) __dead2;
+void used_reserved(char *) __dead2;
 void verbose(void);
 void write_section(const char **);