build: check -Wmissing-prototypes

pstate_clear is lacking a prototype.
Reported by Ryan
https://lists.gnu.org/r/bug-bison/2020-05/msg00101.html

Besides, none of the C examples were compiled with the warning flags.

* configure.ac (warn_c): Add -Wmissing-prototypes.
* data/skeletons/yacc.c (pstate_clear): Make it static.
* examples/local.mk (TEST_CFLAGS): New.
* examples/c/bistromathic/local.mk, examples/c/calc/local.mk,
* examples/c/lexcalc/local.mk, examples/c/mfcalc/local.mk,
* examples/c/pushcalc/local.mk, examples/c/reccalc/local.mk,
* examples/c/rpcalc/local.mk:
Use it.

GCC's warn_unused_result is not silenced by a cast to void, so we have
to "use" scanf's result.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25509
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425

Flex generated code produces too many warnings, including things such
as, with ICC:

    examples/c/lexcalc/scan.c(1088): error #1682: implicit conversion
              of a 64-bit integral type to a smaller integral type (potential portability problem)
    2259                YY_INPUT( (&YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[number_to_move]),
    2260                ^
    2261
    2262

I am tired of trying to fix Flex's output.  The project does not seem
maintained.  We ought to avoid it.  So, for the time being, don't try
to enable warnings with Flex.

* examples/c/bistromathic/parse.y, examples/c/reccalc/scan.l: Fix
warnings.
* doc/bison.texi: Discard scanf's return value to defeat
-Werror=unused-result.

NEWS

@@ -2,6 +2,13 @@ GNU Bison NEWS
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Bug fixes
+
+  Incorrect comments in the generated parsers.
+
+  Warnings in push parsers (yacc.c).
+
+  Incorrect display of gotos in LAC traces (lalr1.cc).
 
 * Noteworthy changes in release 3.6.2 (2020-05-17) [stable]
 

THANKS

@@ -162,6 +162,7 @@ Quoc Peyrot               chojin@lrde.epita.fr
 R Blake                   blakers@mac.com
 Raja R Harinath           harinath@cs.umn.edu
 Ralf Wildenhues           Ralf.Wildenhues@gmx.de
+Ryan                      dev@splintermail.com
 Rich Wilson               richaw@gmail.com
 Richard Stallman          rms@gnu.org
 Rici Lake                 ricilake@gmail.com

configure.ac

@@ -135,7 +135,9 @@ if test "$enable_gcc_warnings" = yes; then
     -Wpointer-arith -Wshadow
     -Wwrite-strings
     -wr188 -wr2259 -wr3179'
-  warn_c='-Wbad-function-cast -Wstrict-prototypes'
+  warn_c='-Wbad-function-cast
+    -Wmissing-prototypes
+    -Wstrict-prototypes'
   warn_cxx='-Wextra-semi -Wnoexcept -Wold-style-cast -Wundefined-func-template
     -Wweak-vtables'
   # Warnings for the test suite only.

data/skeletons/yacc.c

@@ -1480,7 +1480,7 @@ yypull_parse (yypstate *yyps]b4_user_formals[)
 ]b4_parse_state_variable_macros([b4_pstate_macro_define])[
 
 /* Initialize the parser data structure.  */
-void
+static void
 yypstate_clear (yypstate *yyps)
 {
 ]b4_initialize_parser_state_variables[

doc/bison.texi

@@ -1879,6 +1879,7 @@ Here is the code for the lexical analyzer:
    and tabs, and returns 0 for end-of-input. */
 
 #include <ctype.h>
+#include <stdlib.h>
 @end group
 
 @group
@@ -1895,7 +1896,8 @@ yylex (void)
   if (c == '.' || isdigit (c))
     @{
       ungetc (c, stdin);
-      scanf ("%lf", &yylval);
+      if (scanf ("%lf", &yylval) != 1)
+        abort ();
       return NUM;
     @}
 @end group
@@ -2728,7 +2730,8 @@ yylex (void)
   if (c == '.' || isdigit (c))
     @{
       ungetc (c, stdin);
-      scanf ("%lf", &yylval.NUM);
+      if (scanf ("%lf", &yylval.NUM) != 1)
+        abort ();
       return NUM;
     @}
 @end group
@@ -2755,10 +2758,10 @@ Bison generated a definition of @code{YYSTYPE} with a member named
           if (bufsize <= i)
             @{
               bufsize = 2 * bufsize + 40;
-              symbuf = realloc (symbuf, bufsize);
+              symbuf = realloc (symbuf, (size_t) bufsize);
             @}
           /* Add this character to the buffer. */
-          symbuf[i++] = c;
+          symbuf[i++] = (char) c;
           /* Get another character. */
           c = getchar ();
         @}
@@ -10629,7 +10632,7 @@ when there were errors.  No file was generated (except the reports generated
 by @option{--verbose}, etc.).  In particular, the output files that possibly
 existed were not changed.
 
-@item 63 (mistmatch)
+@item 63 (mismatch)
 when @command{bison} does not meet the version requirements of the grammar
 file. @xref{Require Decl}.  No file was generated or changed.
 @end table
@@ -15269,6 +15272,7 @@ London, Department of Computer Science, TR-00-12 (December 2000).
 @c LocalWords: YYUNDEF SymbolKind yypcontext YYENOMEM TOKENMAX getBundle
 @c LocalWords: ResourceBundle myResources getString getName getToken
 @c LocalWords: getLocation getExpectedTokens reportSyntaxError bistromathic
+@c LocalWords: TokenKind
 
 @c Local Variables:
 @c ispell-dictionary: "american"

examples/c/bistromathic/local.mk

@@ -31,6 +31,7 @@ if ENABLE_BISTROMATHIC
     -DBISON_LOCALEDIR='"$(localdir)"'		\
     -DLOCALEDIR='"$(localdir)"'			\
     -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+  %C%_bistromathic_CFLAGS = $(TEST_CFLAGS)
   %C%_bistromathic_LDADD = -lm $(LIBREADLINE) $(LIBINTL)
 endif
 

examples/c/bistromathic/parse.y

@@ -1,7 +1,6 @@
 %require "3.6"
 
 %code top {
-  #include <assert.h>
   #include <ctype.h>  // isdigit
   #include <locale.h> // LC_ALL
   #include <math.h>   // cos, sin, etc.
@@ -218,7 +217,7 @@ getsym (char const *name)
 }
 
 // How many symbols are registered.
-int
+static int
 symbol_count (void)
 {
   int res = 0;
@@ -312,7 +311,7 @@ yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc)
 `---------*/
 
 
-const char *
+static const char *
 error_format_string (int argc)
 {
   switch (argc)
@@ -407,7 +406,8 @@ xstrndup (const char *string, size_t n)
   const char *end = memchr (string, '\0', n);
   size_t len = end ? (size_t) (end - string) : n;
   char *new = malloc (len + 1);
-  assert (new);
+  if (!new)
+    abort ();
   new[len] = '\0';
   return memcpy (new, string, len);
 }
@@ -418,7 +418,8 @@ xstrndup (const char *string, size_t n)
 `-----------*/
 
 // Parse (and execute) this line.
-int process_line (YYLTYPE *lloc, const char *line)
+static int
+process_line (YYLTYPE *lloc, const char *line)
 {
   yypstate *ps = yypstate_new ();
   int status = 0;
@@ -433,7 +434,8 @@ int process_line (YYLTYPE *lloc, const char *line)
 }
 
 // Get the list of possible tokens after INPUT was read.
-int
+// Returns a nonnegative.
+static int
 expected_tokens (const char *input,
                  int *tokens, int ntokens)
 {
@@ -454,6 +456,8 @@ expected_tokens (const char *input,
 
   // Then query for the accepted tokens at this point.
   int res = yypstate_expected_tokens (ps, tokens, ntokens);
+  if (res < 0)
+    abort ();
   yypstate_delete (ps);
   return res;
 }
@@ -463,7 +467,7 @@ expected_tokens (const char *input,
 // TEXT is the word to complete.  We can use the entire contents of
 // rl_line_buffer in case we want to do some simple parsing.  Return
 // the array of matches, or NULL if there aren't any.
-char **
+static char **
 completion (const char *text, int start, int end)
 {
   YYDPRINTF ((stderr, "completion (\"%.*s[%.*s]%s\")\n",
@@ -473,14 +477,17 @@ completion (const char *text, int start, int end)
 
   // Get list of token numbers.
   int tokens[YYNTOKENS];
-  char *line = xstrndup (rl_line_buffer, start);
+  char *line = xstrndup (rl_line_buffer, (size_t) start);
   int ntokens = expected_tokens (line, tokens, YYNTOKENS);
   free (line);
 
   // Build MATCHES, the list of possible completions.
-  const int len = strlen (text);
+  const size_t len = strlen (text);
   // Need initial prefix and final NULL.
-  char **matches = calloc (ntokens + symbol_count () + 2, sizeof *matches);
+  char **matches
+    = calloc ((size_t) ntokens + (size_t) symbol_count () + 2, sizeof *matches);
+  if (!matches)
+    abort ();
   int match = 1;
   for (int i = 0; i < ntokens; ++i)
     switch (tokens[i])
@@ -510,9 +517,9 @@ completion (const char *text, int start, int end)
     matches[0] = strdup (text);
   else
     {
-      int lcplen = strlen (matches[1]);
+      size_t lcplen = strlen (matches[1]);
       for (int i = 2; i < match && lcplen; ++i)
-        for (int j = 0; j < lcplen; ++j)
+        for (size_t j = 0; j < lcplen; ++j)
           if (matches[1][j] != matches[i][j])
             lcplen = j;
       matches[0] = xstrndup (matches[1], lcplen);
@@ -536,7 +543,8 @@ completion (const char *text, int start, int end)
   return matches;
 }
 
-void init_readline (void)
+static void
+init_readline (void)
 {
   // Allow conditional parsing of the ~/.inputrc file.
   rl_readline_name = "bistromathic";
@@ -555,7 +563,8 @@ void init_readline (void)
 | Main.  |
 `-------*/
 
-int main (int argc, char const* argv[])
+int
+main (int argc, char const* argv[])
 {
 #if defined ENABLE_NLS && ENABLE_NLS
   // Set up internationalization.

examples/c/calc/calc.y

@@ -1,6 +1,7 @@
 %code top {
   #include <ctype.h>  /* isdigit. */
-  #include <stdio.h>  /* For printf, etc. */
+  #include <stdio.h>  /* printf. */
+  #include <stdlib.h> /* abort. */
   #include <string.h> /* strcmp. */
 
   int yylex (void);
@@ -73,7 +74,8 @@ yylex (void)
   if (c == '.' || isdigit (c))
     {
       ungetc (c, stdin);
-      scanf ("%lf", &yylval.NUM);
+      if (scanf ("%lf", &yylval.NUM) != 1)
+        abort ();
       return NUM;
     }
 

examples/c/calc/local.mk

@@ -27,6 +27,7 @@ nodist_%C%_calc_SOURCES = %D%/calc.y
 
 # Don't use gnulib's system headers.
 %C%_calc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+%C%_calc_CFLAGS = $(TEST_CFLAGS)
 
 dist_calc_DATA = %D%/calc.y %D%/Makefile %D%/README.md
 CLEANFILES += %D%/calc.[ch] %D%/calc.output %D%/scan.c

examples/c/lexcalc/local.mk

@@ -25,6 +25,8 @@ if FLEX_WORKS
   nodist_%C%_lexcalc_SOURCES = %D%/parse.y %D%/parse.h %D%/scan.l
   # Don't use gnulib's system headers.
   %C%_lexcalc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+  # Fighting warnings triggered by Flex is just too painful.
+  # %C%_lexcalc_CFLAGS = $(TEST_CFLAGS)
 endif FLEX_WORKS
 
 %D%/parse.c: $(dependencies)

examples/c/lexcalc/scan.l

@@ -4,7 +4,7 @@
 %option nodefault noinput nounput noyywrap
 
 %{
-#include <errno.h> /* errno, ERANGE */
+#include <errno.h>  /* errno, ERANGE */
 #include <limits.h> /* INT_MIN */
 #include <stdlib.h> /* strtol */
 
@@ -12,7 +12,7 @@
 
   // Each time a rule is matched, advance the end cursor/position.
 #define YY_USER_ACTION                          \
-  yylloc->last_column += yyleng;
+  yylloc->last_column += (int) yyleng;
 
   // Move the first position onto the last.
 #define LOCATION_STEP()                         \

examples/c/mfcalc/local.mk

@@ -31,6 +31,7 @@ nodist_%C%_mfcalc_SOURCES = $(mfcalc_sources)
 %D%/mfcalc.c: $(dependencies)
 # Don't use gnulib's system headers.
 %C%_mfcalc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+%C%_mfcalc_CFLAGS = $(TEST_CFLAGS)
 %C%_mfcalc_LDADD = -lm
 
 dist_TESTS += %D%/mfcalc.test

examples/c/pushcalc/calc.y

@@ -1,7 +1,7 @@
 %code top {
   #include <ctype.h>  /* isdigit. */
-  #include <stdbool.h>
+  #include <stdio.h>  /* printf. */
-  #include <stdio.h>  /* For printf, etc. */
+  #include <stdlib.h> /* abort. */
   #include <string.h> /* strcmp. */
 }
 
@@ -81,7 +81,8 @@ yylex (YYSTYPE *yylval)
   if (c == '.' || isdigit (c))
     {
       ungetc (c, stdin);
-      scanf ("%lf", &yylval->NUM);
+      if (scanf ("%lf", &yylval->NUM) != 1)
+        abort ();
       return NUM;
     }
 

examples/c/pushcalc/local.mk

@@ -27,6 +27,7 @@ nodist_%C%_calc_SOURCES = %D%/calc.y
 
 # Don't use gnulib's system headers.
 %C%_calc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+%C%_calc_CFLAGS = $(TEST_CFLAGS)
 
 dist_pushcalc_DATA = %D%/calc.y %D%/Makefile %D%/README.md
 CLEANFILES += %D%/calc.[ch] %D%/calc.output

examples/c/reccalc/local.mk

@@ -26,6 +26,8 @@ if FLEX_WORKS
   BUILT_SOURCES += $(nodist_%C%_reccalc_SOURCES)
   # Don't use gnulib's system headers.
   %C%_reccalc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+  # Fighting warnings triggered by Flex is just too painful.
+  # %C%_reccalc_CFLAGS = $(TEST_CFLAGS)
 endif FLEX_WORKS
 
 %D%/parse.c: $(dependencies)

examples/c/reccalc/scan.l

@@ -32,9 +32,9 @@
         do                                              \
           capacity = capacity ? 2 * capacity : 128;     \
         while (capacity < size + yyleng + 1);           \
-        str = realloc (str, capacity);                  \
+        str = realloc (str, (size_t) capacity);         \
       }                                                 \
-    memcpy (str + size, yytext, yyleng);                \
+    memcpy (str + size, yytext, (size_t) yyleng);       \
     size += yyleng;                                     \
     assert (size < capacity);                           \
   } while (0)

examples/c/rpcalc/local.mk

@@ -31,6 +31,7 @@ nodist_%C%_rpcalc_SOURCES = $(rpcalc_sources)
 %D%/rpcalc.c: $(dependencies)
 # Don't use gnulib's system headers.
 %C%_rpcalc_CPPFLAGS = -I$(top_builddir)/%D%
+%C%_rpcalc_CFLAGS = $(TEST_CFLAGS)
 %C%_rpcalc_LDADD = -lm
 
 dist_TESTS += %D%/rpcalc.test

examples/local.mk

@@ -35,6 +35,9 @@
 dist_noinst_SCRIPTS = %D%/extexi %D%/test
 TEST_LOG_COMPILER = $(SHELL) $(top_srcdir)/%D%/test
 
+TEST_CFLAGS =						\
+  $(WARN_CFLAGS) $(WARN_CFLAGS_TEST) $(WERROR_CFLAGS)
+
 AM_CXXFLAGS =							\
   $(WARN_CXXFLAGS) $(WARN_CXXFLAGS_TEST) $(WERROR_CXXFLAGS)