+
+/* MUSCLE is an M4 list of pairs. Create or extend it with the pair
+ (A1, A2) after escaping both values with digraphs. Note that because the
+ muscle values are output *double* quoted, one needs to strip the first level
+ of quotes to reach the list itself. */
+void muscle_pair_list_grow (const char *muscle,
+ const char *a1, const char *a2);
+
+/* In the format `[[file_name:line.column]], [[file_name:line.column]]', append
+ LOC to MUSCLE. Use digraphs for special characters in each file name. */
+void muscle_location_grow (char const *key, location loc);
+
+/* In the format `file_name:line.column', append BOUND to MUSCLE. Use digraphs
+ for special characters in the file name. */
+void muscle_boundary_grow (char const *key, boundary bound);
+
+/* Grow KEY for the occurrence of the name USER_NAME at LOC appropriately for
+ use with b4_check_user_names in ../data/bison.m4. USER_NAME is not escaped
+ with digraphs, so it must not contain `[' or `]'. */
+void muscle_user_name_list_grow (char const *key, char const *user_name,
+ location loc);
+
+/* Define the muscle for the %define variable VARIABLE appearing at
+ VARIABLE_LOC in the grammar file with value VALUE. Warn if VARIABLE is
+ already defined. Record this as a grammar occurrence of VARIABLE by
+ invoking muscle_user_name_list_grow. */
+void muscle_percent_define_insert (char const *variable, location variable_loc,
+ char const *value);
+
+/* Mimic b4_percent_define_get in ../data/bison.m4 exactly. That is, if the
+ %define variable VARIABLE is defined, return its value. Otherwise, return
+ the empty string. Also, record Bison's usage of VARIABLE by defining
+ b4_percent_define_bison_variables(VARIABLE). The caller is responsible for
+ freeing the memory of the returned string. */
+char *muscle_percent_define_get (char const *variable);
+
+/* Mimic muscle_percent_define_get_loc in ../data/bison.m4 exactly. That is,
+ if the %define variable VARIABLE is undefined, complain fatally since that's
+ a Bison error. Otherwise, return its definition location in a form
+ approriate for the first argument of warn_at, complain_at, or fatal_at.
+ Don't record this as a Bison usage of VARIABLE as there's no reason to
+ suspect that the user-supplied value has yet influenced the output. */
+location muscle_percent_define_get_loc (char const *variable);
+
+/* Mimic muscle_percent_define_get_syncline in ../data/bison.m4 exactly. That
+ is, if the %define variable VARIABLE is undefined, complain fatally since
+ that's a Bison error. Otherwise, return its definition location as a
+ b4_syncline invocation. Don't record this as a Bison usage of VARIABLE as
+ there's no reason to suspect that the user-supplied value has yet influenced
+ the output. */
+char const *muscle_percent_define_get_syncline (char const *variable);
+
+/* Mimic b4_percent_define_ifdef in ../data/bison.m4 exactly. That is, if the
+ %define variable VARIABLE is defined, return true. Otherwise, return false.
+ Also, record Bison's usage of VARIABLE by defining
+ b4_percent_define_bison_variables(VARIABLE). */
+bool muscle_percent_define_ifdef (char const *variable);
+
+/* Mimic b4_percent_define_flag_if in ../data/bison.m4 exactly. That is, if
+ the %define variable VARIABLE is defined to "" or "true", return true. If
+ it is defined to "false", return false. Complain if it is undefined (a
+ Bison error since the default value should have been set already) or defined
+ to any other value (possibly a user error). Also, record Bison's usage of
+ VARIABLE by defining b4_percent_define_bison_variables(VARIABLE). */
+bool muscle_percent_define_flag_if (char const *variable);
+
+/* Mimic b4_percent_define_default in ../data/bison.m4 exactly. That is, if
+ the %define variable VARIABLE is undefined, set its value to VALUE.
+ Don't record this as a Bison usage of VARIABLE as there's no reason to
+ suspect that the value has yet influenced the output. */
+void muscle_percent_define_default (char const *variable, char const *value);
+
+/* Mimic b4_percent_define_check_values in ../data/bison.m4 exactly except that
+ the VALUES structure is more appropriate for C. That is, VALUES points to a
+ list of strings that is partitioned into sublists by NULL's, one terminating
+ each sublist. The last sublist is followed by a second NULL. For each
+ sublist, the first string is the name of a %define variable, and all
+ remaining strings in that sublist are the valid values for that variable.
+ Complain if such a variable is undefined (a Bison error since the default
+ value should have been set already) or defined to any other value (possibly
+ a user error). Don't record this as a Bison usage of the variable as
+ there's no reason to suspect that the value has yet influenced the
+ output. */
+void muscle_percent_define_check_values (char const * const *values);
+
+/* Grow the muscle for the %code qualifier QUALIFIER appearing at QUALIFIER_LOC
+ in the grammar file with code CODE appearing at CODE_LOC. Record this as a
+ grammar occurrence of VARIABLE by invoking muscle_user_name_list_grow. */
+void muscle_percent_code_grow (char const *qualifier, location qualifier_loc,
+ char const *code, location code_loc);
+
+void muscles_m4_output (FILE *out);