diff --git a/gcc/fortran/array.cc b/gcc/fortran/array.cc
index be5eb8b6a0f..4b7c1e715bf 100644
--- a/gcc/fortran/array.cc
+++ b/gcc/fortran/array.cc
@@ -994,7 +994,7 @@ compare_bounds (gfc_expr *bound1, gfc_expr *bound2)
 /* Compares two array specifications.  They must be constant or deferred
    shape.  */
 
-int
+bool
 gfc_compare_array_spec (gfc_array_spec *as1, gfc_array_spec *as2)
 {
   int i;
@@ -1039,7 +1039,7 @@ gfc_compare_array_spec (gfc_array_spec *as1, gfc_array_spec *as2)
    use the symbol as an implied-DO iterator.  Returns nonzero if a
    duplicate was found.  */
 
-static int
+static bool
 check_duplicate_iterator (gfc_constructor_base base, gfc_symbol *master)
 {
   gfc_constructor *c;
@@ -1982,7 +1982,7 @@ is_constant_element (gfc_expr *e)
    i=1,100000000) /) will take a while as* opposed to a more clever
    function that traverses the expression tree. FIXME.  */
 
-int
+bool
 gfc_constant_ac (gfc_expr *e)
 {
   expand_info expand_save;
@@ -2005,7 +2005,7 @@ gfc_constant_ac (gfc_expr *e)
 /* Returns nonzero if an array constructor has been completely
    expanded (no iterators) and zero if iterators are present.  */
 
-int
+bool
 gfc_expanded_ac (gfc_expr *e)
 {
   gfc_constructor *c;
diff --git a/gcc/fortran/check.cc b/gcc/fortran/check.cc
index b348bda6e6c..4e3aed84b9d 100644
--- a/gcc/fortran/check.cc
+++ b/gcc/fortran/check.cc
@@ -1156,7 +1156,7 @@ dim_rank_check (gfc_expr *dim, gfc_expr *array, int allow_assumed)
    dimension bi, returning 0 if they are known not to be identical,
    and 1 if they are identical, or if this cannot be determined.  */
 
-static int
+static bool
 identical_dimen_shape (gfc_expr *a, int ai, gfc_expr *b, int bi)
 {
   mpz_t a_size, b_size;
diff --git a/gcc/fortran/cpp.cc b/gcc/fortran/cpp.cc
index c3b7c7f7bd9..d7890a97287 100644
--- a/gcc/fortran/cpp.cc
+++ b/gcc/fortran/cpp.cc
@@ -297,7 +297,7 @@ gfc_cpp_init_options (unsigned int decoded_options_count,
   gfc_cpp_option.deferred_opt_count = 0;
 }
 
-int
+bool
 gfc_cpp_handle_option (size_t scode, const char *arg, int value ATTRIBUTE_UNUSED)
 {
   int result = 1;
@@ -749,7 +749,6 @@ gfc_cpp_add_include_path_after (char *path, bool user_supplied)
 
 static void scan_translation_unit_trad (cpp_reader *);
 static void account_for_newlines (const unsigned char *, size_t);
-static int dump_macro (cpp_reader *, cpp_hashnode *, void *);
 
 static void print_line (location_t, const char *);
 static void maybe_print_line (location_t);
diff --git a/gcc/fortran/cpp.h b/gcc/fortran/cpp.h
index 886996f2784..d2fbfcf9525 100644
--- a/gcc/fortran/cpp.h
+++ b/gcc/fortran/cpp.h
@@ -39,7 +39,7 @@ void gfc_cpp_init (void);
 void gfc_cpp_init_options (unsigned int decoded_options_count,
 			   struct cl_decoded_option *decoded_options);
 
-int gfc_cpp_handle_option(size_t scode, const char *arg, int value);
+bool gfc_cpp_handle_option(size_t scode, const char *arg, int value);
 
 void gfc_cpp_post_options (bool);
 
diff --git a/gcc/fortran/dependency.cc b/gcc/fortran/dependency.cc
index a648d5c7903..b398b29a642 100644
--- a/gcc/fortran/dependency.cc
+++ b/gcc/fortran/dependency.cc
@@ -921,7 +921,7 @@ gfc_ref_needs_temporary_p (gfc_ref *ref)
 }
 
 
-static int
+static bool
 gfc_is_data_pointer (gfc_expr *e)
 {
   gfc_ref *ref;
@@ -1091,7 +1091,7 @@ gfc_check_argument_dependency (gfc_expr *other, sym_intent intent,
 /* Like gfc_check_argument_dependency, but check all the arguments in ACTUAL.
    FNSYM is the function being called, or NULL if not known.  */
 
-int
+bool
 gfc_check_fncall_dependency (gfc_expr *other, sym_intent intent,
 			     gfc_symbol *fnsym, gfc_actual_arglist *actual,
 			     gfc_dep_check elemental)
@@ -1137,7 +1137,7 @@ gfc_check_fncall_dependency (gfc_expr *other, sym_intent intent,
    e1->ref and e2->ref to determine whether the actually accessed
    portions of these variables/arrays potentially overlap.  */
 
-int
+bool
 gfc_are_equivalenced_arrays (gfc_expr *e1, gfc_expr *e2)
 {
   gfc_equiv_list *l;
@@ -2098,7 +2098,7 @@ ref_same_as_full_array (gfc_ref *full_ref, gfc_ref *ref)
 	    there is some kind of overlap.
 	0 : array references are identical or not overlapping.  */
 
-int
+bool
 gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse,
 		  bool identical)
 {
diff --git a/gcc/fortran/dependency.h b/gcc/fortran/dependency.h
index b1150316f5d..fbbede8b22c 100644
--- a/gcc/fortran/dependency.h
+++ b/gcc/fortran/dependency.h
@@ -32,13 +32,13 @@ enum gfc_dep_check
 bool gfc_ref_needs_temporary_p (gfc_ref *);
 bool gfc_full_array_ref_p (gfc_ref *, bool *);
 gfc_expr *gfc_get_noncopying_intrinsic_argument (gfc_expr *);
-int gfc_check_fncall_dependency (gfc_expr *, sym_intent, gfc_symbol *,
+bool gfc_check_fncall_dependency (gfc_expr *, sym_intent, gfc_symbol *,
 				 gfc_actual_arglist *, gfc_dep_check);
 int gfc_check_dependency (gfc_expr *, gfc_expr *, bool);
 int gfc_expr_is_one (gfc_expr *, int);
 
-int gfc_dep_resolver (gfc_ref *, gfc_ref *, gfc_reverse *,
+bool gfc_dep_resolver (gfc_ref *, gfc_ref *, gfc_reverse *,
 		      bool identical = false);
-int gfc_are_equivalenced_arrays (gfc_expr *, gfc_expr *);
+bool gfc_are_equivalenced_arrays (gfc_expr *, gfc_expr *);
 
 gfc_expr * gfc_discard_nops (gfc_expr *);
diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index d91722e6ac6..aa01a4d3d22 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -798,7 +798,7 @@ gfc_copy_ref (gfc_ref *src)
 
 /* Detect whether an expression has any vector index array references.  */
 
-int
+bool
 gfc_has_vector_index (gfc_expr *e)
 {
   gfc_ref *ref;
@@ -888,7 +888,7 @@ gfc_kind_max (gfc_expr *e1, gfc_expr *e2)
 
 /* Returns nonzero if the type is numeric, zero otherwise.  */
 
-static int
+static bool
 numeric_type (bt type)
 {
   return type == BT_COMPLEX || type == BT_REAL || type == BT_INTEGER;
@@ -897,7 +897,7 @@ numeric_type (bt type)
 
 /* Returns nonzero if the typespec is a numeric type, zero otherwise.  */
 
-int
+bool
 gfc_numeric_ts (gfc_typespec *ts)
 {
   return numeric_type (ts->type);
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index ac21e1813d9..9dd6b45f112 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -3220,16 +3220,16 @@ void gfc_release_include_path (void);
 void gfc_check_include_dirs (bool);
 FILE *gfc_open_included_file (const char *, bool, bool);
 
-int gfc_at_end (void);
-int gfc_at_eof (void);
-int gfc_at_bol (void);
-int gfc_at_eol (void);
+bool gfc_at_end (void);
+bool gfc_at_eof (void);
+bool gfc_at_bol (void);
+bool gfc_at_eol (void);
 void gfc_advance_line (void);
-int gfc_define_undef_line (void);
+bool gfc_define_undef_line (void);
 
-int gfc_wide_is_printable (gfc_char_t);
-int gfc_wide_is_digit (gfc_char_t);
-int gfc_wide_fits_in_byte (gfc_char_t);
+bool gfc_wide_is_printable (gfc_char_t);
+bool gfc_wide_is_digit (gfc_char_t);
+bool gfc_wide_fits_in_byte (gfc_char_t);
 gfc_char_t gfc_wide_tolower (gfc_char_t);
 gfc_char_t gfc_wide_toupper (gfc_char_t);
 size_t gfc_wide_strlen (const gfc_char_t *);
@@ -3487,7 +3487,7 @@ void gfc_release_symbol (gfc_symbol *&);
 gfc_symbol *gfc_new_symbol (const char *, gfc_namespace *);
 gfc_symtree* gfc_find_symtree_in_proc (const char *, gfc_namespace *);
 int gfc_find_symbol (const char *, gfc_namespace *, int, gfc_symbol **);
-int gfc_find_sym_tree (const char *, gfc_namespace *, int, gfc_symtree **);
+bool gfc_find_sym_tree (const char *, gfc_namespace *, int, gfc_symtree **);
 int gfc_get_symbol (const char *, gfc_namespace *, gfc_symbol **);
 bool gfc_verify_c_interop (gfc_typespec *);
 bool gfc_verify_c_interop_param (gfc_symbol *);
@@ -3567,10 +3567,10 @@ bool gfc_convert_type (gfc_expr *, gfc_typespec *, int);
 bool gfc_convert_type_warn (gfc_expr *, gfc_typespec *, int, int,
 			    bool array = false);
 bool gfc_convert_chartype (gfc_expr *, gfc_typespec *);
-int gfc_generic_intrinsic (const char *);
-int gfc_specific_intrinsic (const char *);
+bool gfc_generic_intrinsic (const char *);
+bool gfc_specific_intrinsic (const char *);
 bool gfc_is_intrinsic (gfc_symbol*, int, locus);
-int gfc_intrinsic_actual_ok (const char *, const bool);
+bool gfc_intrinsic_actual_ok (const char *, const bool);
 gfc_intrinsic_sym *gfc_find_function (const char *);
 gfc_intrinsic_sym *gfc_find_subroutine (const char *);
 gfc_intrinsic_sym *gfc_intrinsic_function_by_id (gfc_isym_id);
@@ -3648,7 +3648,7 @@ void gfc_type_convert_binary (gfc_expr *, int);
 bool gfc_is_constant_expr (gfc_expr *);
 bool gfc_simplify_expr (gfc_expr *, int);
 bool gfc_try_simplify_expr (gfc_expr *, int);
-int gfc_has_vector_index (gfc_expr *);
+bool gfc_has_vector_index (gfc_expr *);
 
 gfc_expr *gfc_get_expr (void);
 gfc_expr *gfc_get_array_expr (bt type, int kind, locus *);
@@ -3672,7 +3672,7 @@ gfc_ref* gfc_copy_ref (gfc_ref*);
 
 bool gfc_specification_expr (gfc_expr *);
 
-int gfc_numeric_ts (gfc_typespec *);
+bool gfc_numeric_ts (gfc_typespec *);
 int gfc_kind_max (gfc_expr *, gfc_expr *);
 
 bool gfc_check_conformance (gfc_expr *, gfc_expr *, const char *, ...) ATTRIBUTE_PRINTF_3;
@@ -3737,11 +3737,11 @@ void gfc_resolve (gfc_namespace *);
 void gfc_resolve_code (gfc_code *, gfc_namespace *);
 void gfc_resolve_blocks (gfc_code *, gfc_namespace *);
 void gfc_resolve_formal_arglist (gfc_symbol *);
-int gfc_impure_variable (gfc_symbol *);
-int gfc_pure (gfc_symbol *);
-int gfc_implicit_pure (gfc_symbol *);
+bool gfc_impure_variable (gfc_symbol *);
+bool gfc_pure (gfc_symbol *);
+bool gfc_implicit_pure (gfc_symbol *);
 void gfc_unset_implicit_pure (gfc_symbol *);
-int gfc_elemental (gfc_symbol *);
+bool gfc_elemental (gfc_symbol *);
 bool gfc_resolve_iterator (gfc_iterator *, bool, bool);
 bool find_forall_index (gfc_expr *, gfc_symbol *, int);
 bool gfc_resolve_index (gfc_expr *, int);
@@ -3755,8 +3755,8 @@ bool gfc_resolve_intrinsic (gfc_symbol *, locus *);
 bool gfc_explicit_interface_required (gfc_symbol *, char *, int);
 extern int gfc_do_concurrent_flag;
 const char* gfc_lookup_function_fuzzy (const char *, gfc_symtree *);
-int gfc_pure_function (gfc_expr *e, const char **name);
-int gfc_implicit_pure_function (gfc_expr *e);
+bool gfc_pure_function (gfc_expr *e, const char **name);
+bool gfc_implicit_pure_function (gfc_expr *e);
 
 
 /* array.cc */
@@ -3769,12 +3769,12 @@ bool gfc_set_array_spec (gfc_symbol *, gfc_array_spec *, locus *);
 gfc_array_spec *gfc_copy_array_spec (gfc_array_spec *);
 bool gfc_resolve_array_spec (gfc_array_spec *, int);
 
-int gfc_compare_array_spec (gfc_array_spec *, gfc_array_spec *);
+bool gfc_compare_array_spec (gfc_array_spec *, gfc_array_spec *);
 
 void gfc_simplify_iterator_var (gfc_expr *);
 bool gfc_expand_constructor (gfc_expr *, bool);
-int gfc_constant_ac (gfc_expr *);
-int gfc_expanded_ac (gfc_expr *);
+bool gfc_constant_ac (gfc_expr *);
+bool gfc_expanded_ac (gfc_expr *);
 bool gfc_resolve_character_array_constructor (gfc_expr *);
 bool gfc_resolve_array_constructor (gfc_expr *);
 bool gfc_check_constructor_type (gfc_expr *);
@@ -3859,7 +3859,7 @@ symbol_attribute gfc_expr_attr (gfc_expr *);
 symbol_attribute gfc_caf_attr (gfc_expr *, bool i = false, bool *r = NULL);
 match gfc_match_rvalue (gfc_expr **);
 match gfc_match_varspec (gfc_expr*, int, bool, bool);
-int gfc_check_digit (char, int);
+bool gfc_check_digit (char, int);
 bool gfc_is_function_return_value (gfc_symbol *, gfc_namespace *);
 bool gfc_convert_to_structure_constructor (gfc_expr *, gfc_symbol *,
 					      gfc_expr **,
diff --git a/gcc/fortran/intrinsic.cc b/gcc/fortran/intrinsic.cc
index b5ef664eb33..74970e567fc 100644
--- a/gcc/fortran/intrinsic.cc
+++ b/gcc/fortran/intrinsic.cc
@@ -1107,7 +1107,7 @@ gfc_find_subroutine (const char *name)
 /* Given a string, figure out if it is the name of a generic intrinsic
    function or not.  */
 
-int
+bool
 gfc_generic_intrinsic (const char *name)
 {
   gfc_intrinsic_sym *sym;
@@ -1120,7 +1120,7 @@ gfc_generic_intrinsic (const char *name)
 /* Given a string, figure out if it is the name of a specific
    intrinsic function or not.  */
 
-int
+bool
 gfc_specific_intrinsic (const char *name)
 {
   gfc_intrinsic_sym *sym;
@@ -1132,7 +1132,7 @@ gfc_specific_intrinsic (const char *name)
 
 /* Given a string, figure out if it is the name of an intrinsic function
    or subroutine allowed as an actual argument or not.  */
-int
+bool
 gfc_intrinsic_actual_ok (const char *name, const bool subroutine_flag)
 {
   gfc_intrinsic_sym *sym;
diff --git a/gcc/fortran/io.cc b/gcc/fortran/io.cc
index 594f609cbf7..f0c605ebd80 100644
--- a/gcc/fortran/io.cc
+++ b/gcc/fortran/io.cc
@@ -2010,15 +2010,6 @@ gfc_free_open (gfc_open *open)
   free (open);
 }
 
-
-static int
-compare_to_allowed_values (const char *specifier, const char *allowed[],
-			   const char *allowed_f2003[],
-			   const char *allowed_gnu[], gfc_char_t *value,
-			   const char *statement, bool warn, locus *where,
-			   int *num = NULL);
-
-
 static bool
 check_open_constraints (gfc_open *open, locus *where);
 
@@ -2062,12 +2053,12 @@ gfc_resolve_open (gfc_open *open, locus *where)
    value if it is not allowed.  */
 
 
-static int
+static bool
 compare_to_allowed_values (const char *specifier, const char *allowed[],
 			   const char *allowed_f2003[],
 			   const char *allowed_gnu[], gfc_char_t *value,
 			   const char *statement, bool warn, locus *where,
-			   int *num)
+			   int *num = NULL)
 {
   int i;
   unsigned int len;
diff --git a/gcc/fortran/parse.cc b/gcc/fortran/parse.cc
index f1e55316e5b..5e2a95688d2 100644
--- a/gcc/fortran/parse.cc
+++ b/gcc/fortran/parse.cc
@@ -4710,7 +4710,7 @@ done:
    context that causes it to become redefined.  If the symbol is an
    iterator, we generate an error message and return nonzero.  */
 
-int
+bool
 gfc_check_do_variable (gfc_symtree *st)
 {
   gfc_state_data *s;
diff --git a/gcc/fortran/parse.h b/gcc/fortran/parse.h
index 75aac8bb2a1..cc57e7d5729 100644
--- a/gcc/fortran/parse.h
+++ b/gcc/fortran/parse.h
@@ -63,7 +63,7 @@ extern gfc_state_data *gfc_state_stack;
 #define gfc_comp_struct(s) \
   ((s) == COMP_DERIVED || (s) == COMP_STRUCTURE || (s) == COMP_MAP)
 
-int gfc_check_do_variable (gfc_symtree *);
+bool gfc_check_do_variable (gfc_symtree *);
 bool gfc_find_state (gfc_compile_state);
 gfc_state_data *gfc_enclosing_unit (gfc_compile_state *);
 const char *gfc_ascii_statement (gfc_statement, bool strip_sentinel = false) ;
diff --git a/gcc/fortran/primary.cc b/gcc/fortran/primary.cc
index 077489ab96e..3099f82850c 100644
--- a/gcc/fortran/primary.cc
+++ b/gcc/fortran/primary.cc
@@ -109,10 +109,10 @@ get_kind (int *is_iso_c)
 /* Given a character and a radix, see if the character is a valid
    digit in that radix.  */
 
-int
+bool
 gfc_check_digit (char c, int radix)
 {
-  int r;
+  bool r;
 
   switch (radix)
     {
diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 58f05a3e74a..9c92958a397 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -1585,7 +1585,7 @@ resolve_structure_cons (gfc_expr *expr, int init)
 /* Returns 0 if a symbol was not declared with a type or
    attribute declaration statement, nonzero otherwise.  */
 
-static int
+static bool
 was_declared (gfc_symbol *sym)
 {
   symbol_attribute a;
@@ -3091,13 +3091,13 @@ is_external_proc (gfc_symbol *sym)
 /* Figure out if a function reference is pure or not.  Also set the name
    of the function for a potential error message.  Return nonzero if the
    function is PURE, zero if not.  */
-static int
+static bool
 pure_stmt_function (gfc_expr *, gfc_symbol *);
 
-int
+bool
 gfc_pure_function (gfc_expr *e, const char **name)
 {
-  int pure;
+  bool pure;
   gfc_component *comp;
 
   *name = NULL;
@@ -3137,7 +3137,7 @@ gfc_pure_function (gfc_expr *e, const char **name)
 
 /* Check if the expression is a reference to an implicitly pure function.  */
 
-int
+bool
 gfc_implicit_pure_function (gfc_expr *e)
 {
   gfc_component *comp = gfc_get_proc_ptr_comp (e);
@@ -3168,7 +3168,7 @@ impure_stmt_fcn (gfc_expr *e, gfc_symbol *sym,
 }
 
 
-static int
+static bool
 pure_stmt_function (gfc_expr *e, gfc_symbol *sym)
 {
   return gfc_traverse_expr (e, sym, impure_stmt_fcn, 0) ? 0 : 1;
@@ -7630,7 +7630,7 @@ resolve_forall_iterators (gfc_forall_iterator *it)
    PRIVATE.  The search is recursive if necessary.  Returns zero if no
    inaccessible components are found, nonzero otherwise.  */
 
-static int
+static bool
 derived_inaccessible (gfc_symbol *sym)
 {
   gfc_component *c;
@@ -17126,7 +17126,7 @@ resolve_data (gfc_data *d)
 /* Determines if a variable is not 'pure', i.e., not assignable within a pure
    procedure.  Returns zero if assignment is OK, nonzero if there is a
    problem.  */
-int
+bool
 gfc_impure_variable (gfc_symbol *sym)
 {
   gfc_symbol *proc;
@@ -17161,7 +17161,7 @@ gfc_impure_variable (gfc_symbol *sym)
 /* Test whether a symbol is pure or not.  For a NULL pointer, checks if the
    current namespace is inside a pure procedure.  */
 
-int
+bool
 gfc_pure (gfc_symbol *sym)
 {
   symbol_attribute attr;
@@ -17193,7 +17193,7 @@ gfc_pure (gfc_symbol *sym)
    checks if the current namespace is implicitly pure.  Note that this
    function returns false for a PURE procedure.  */
 
-int
+bool
 gfc_implicit_pure (gfc_symbol *sym)
 {
   gfc_namespace *ns;
@@ -17247,7 +17247,7 @@ gfc_unset_implicit_pure (gfc_symbol *sym)
 
 /* Test whether the current procedure is elemental or not.  */
 
-int
+bool
 gfc_elemental (gfc_symbol *sym)
 {
   symbol_attribute attr;
diff --git a/gcc/fortran/scanner.cc b/gcc/fortran/scanner.cc
index 4f45da44607..9f0d9a7dc5e 100644
--- a/gcc/fortran/scanner.cc
+++ b/gcc/fortran/scanner.cc
@@ -56,7 +56,7 @@ gfc_directorylist *include_dirs, *intrinsic_modules_dirs;
 
 static gfc_file *file_head, *current_file;
 
-static int continue_flag, end_flag, gcc_attribute_flag;
+static bool continue_flag, end_flag, gcc_attribute_flag;
 /* If !$omp/!$acc occurred in current comment line.  */
 static int openmp_flag, openacc_flag;
 static int continue_count, continue_line;
@@ -86,7 +86,7 @@ static gfc_char_t *last_error_char;
 /* Functions dealing with our wide characters (gfc_char_t) and
    sequences of such characters.  */
 
-int
+bool
 gfc_wide_fits_in_byte (gfc_char_t c)
 {
   return (c <= UCHAR_MAX);
@@ -98,7 +98,7 @@ wide_is_ascii (gfc_char_t c)
   return (gfc_wide_fits_in_byte (c) && ((unsigned char) c & ~0x7f) == 0);
 }
 
-int
+bool
 gfc_wide_is_printable (gfc_char_t c)
 {
   return (gfc_wide_fits_in_byte (c) && ISPRINT ((unsigned char) c));
@@ -116,7 +116,7 @@ gfc_wide_toupper (gfc_char_t c)
   return (wide_is_ascii (c) ? (gfc_char_t) TOUPPER((unsigned char) c) : c);
 }
 
-int
+bool
 gfc_wide_is_digit (gfc_char_t c)
 {
   return (c >= '0' && c <= '9');
@@ -518,7 +518,7 @@ gfc_open_included_file (const char *name, bool include_cwd, bool module)
 
 /* Test to see if we're at the end of the main source file.  */
 
-int
+bool
 gfc_at_end (void)
 {
   return end_flag;
@@ -527,7 +527,7 @@ gfc_at_end (void)
 
 /* Test to see if we're at the end of the current file.  */
 
-int
+bool
 gfc_at_eof (void)
 {
   if (gfc_at_end ())
@@ -545,7 +545,7 @@ gfc_at_eof (void)
 
 /* Test to see if we're at the beginning of a new line.  */
 
-int
+bool
 gfc_at_bol (void)
 {
   if (gfc_at_eof ())
@@ -557,7 +557,7 @@ gfc_at_bol (void)
 
 /* Test to see if we're at the end of a line.  */
 
-int
+bool
 gfc_at_eol (void)
 {
   if (gfc_at_eof ())
@@ -702,7 +702,7 @@ skip_comment_line (void)
 }
 
 
-int
+bool
 gfc_define_undef_line (void)
 {
   char *tmp;
@@ -1803,7 +1803,7 @@ gfc_gobble_whitespace (void)
 	 easily report line and column numbers consistent with other 
 	 parts of gfortran.  */
 
-static int
+static bool
 load_line (FILE *input, gfc_char_t **pbuf, int *pbuflen, const int *first_char)
 {
   int c, maxlen, i, preprocessor_flag, buflen = *pbuflen;
diff --git a/gcc/fortran/symbol.cc b/gcc/fortran/symbol.cc
index 221165d6dac..b4b36e27d75 100644
--- a/gcc/fortran/symbol.cc
+++ b/gcc/fortran/symbol.cc
@@ -3216,7 +3216,7 @@ gfc_find_symtree_in_proc (const char* name, gfc_namespace* ns)
    any parent namespaces if requested by a nonzero parent_flag.
    Returns nonzero if the name is ambiguous.  */
 
-int
+bool
 gfc_find_sym_tree (const char *name, gfc_namespace *ns, int parent_flag,
 		   gfc_symtree **result)
 {
diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 785cf504816..9f8aa09673a 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -4982,7 +4982,7 @@ done:
 /* Return true if both symbols could refer to the same data object.  Does
    not take account of aliasing due to equivalence statements.  */
 
-static int
+static bool
 symbols_could_alias (gfc_symbol *lsym, gfc_symbol *rsym, bool lsym_pointer,
 		     bool lsym_target, bool rsym_pointer, bool rsym_target)
 {
diff --git a/gcc/fortran/trans-decl.cc b/gcc/fortran/trans-decl.cc
index 18e2b8b78b4..cd32542eb86 100644
--- a/gcc/fortran/trans-decl.cc
+++ b/gcc/fortran/trans-decl.cc
@@ -483,7 +483,7 @@ gfc_set_decl_assembler_name (tree decl, tree name)
 
 /* Returns true if a variable of specified size should go on the stack.  */
 
-int
+bool
 gfc_can_put_var_on_stack (tree size)
 {
   unsigned HOST_WIDE_INT low;
diff --git a/gcc/fortran/trans-types.cc b/gcc/fortran/trans-types.cc
index fc5c221a301..d718f28cc86 100644
--- a/gcc/fortran/trans-types.cc
+++ b/gcc/fortran/trans-types.cc
@@ -1374,7 +1374,7 @@ gfc_get_element_type (tree type)
 
 /* Returns true if the array sym does not require a descriptor.  */
 
-int
+bool
 gfc_is_nodesc_array (gfc_symbol * sym)
 {
   symbol_attribute *array_attr;
@@ -2451,7 +2451,7 @@ gfc_add_field_to_struct (tree context, tree name, tree type, tree **chain)
    the two derived type symbols are "equal", as described
    in 4.4.2 and resolved by gfc_compare_derived_types.  */
 
-int
+bool
 gfc_copy_dt_decls_ifequal (gfc_symbol *from, gfc_symbol *to,
 			   bool from_gsym)
 {
@@ -2940,7 +2940,7 @@ copy_derived_types:
 }
 
 
-int
+bool
 gfc_return_by_reference (gfc_symbol * sym)
 {
   if (!sym->attr.function)
diff --git a/gcc/fortran/trans-types.h b/gcc/fortran/trans-types.h
index 2dc692325cf..d5746ca4366 100644
--- a/gcc/fortran/trans-types.h
+++ b/gcc/fortran/trans-types.h
@@ -88,7 +88,7 @@ tree gfc_get_character_type_len_for_eltype (tree, tree);
 tree gfc_sym_type (gfc_symbol *, bool is_bind_c_arg = false);
 tree gfc_get_cfi_type (int dimen, bool restricted);
 tree gfc_typenode_for_spec (gfc_typespec *, int c = 0);
-int gfc_copy_dt_decls_ifequal (gfc_symbol *, gfc_symbol *, bool);
+bool gfc_copy_dt_decls_ifequal (gfc_symbol *, gfc_symbol *, bool);
 
 tree gfc_get_function_type (gfc_symbol *, gfc_actual_arglist *args = NULL,
 			    const char *fnspec = NULL);
@@ -109,10 +109,10 @@ tree gfc_add_field_to_struct (tree, tree, tree, tree **);
 void gfc_finish_type (tree);
 
 /* Some functions have an extra parameter for the return value.  */
-int gfc_return_by_reference (gfc_symbol *);
+bool gfc_return_by_reference (gfc_symbol *);
 
 /* Returns true if the array sym does not require a descriptor.  */
-int gfc_is_nodesc_array (gfc_symbol *);
+bool gfc_is_nodesc_array (gfc_symbol *);
 
 /* Return the DTYPE for an array.  */
 tree gfc_get_dtype_rank_type (int, tree);
diff --git a/gcc/fortran/trans.h b/gcc/fortran/trans.h
index 1ad6d944fcf..0c8d004736d 100644
--- a/gcc/fortran/trans.h
+++ b/gcc/fortran/trans.h
@@ -670,7 +670,7 @@ void gfc_restore_sym (gfc_symbol *, gfc_saved_var *);
 void gfc_set_decl_assembler_name (tree, tree);
 
 /* Returns true if a variable of specified size should go on the stack.  */
-int gfc_can_put_var_on_stack (tree);
+bool gfc_can_put_var_on_stack (tree);
 
 /* Set GFC_DECL_SCALAR_* on decl from sym if needed.  */
 void gfc_finish_decl_attrs (tree, symbol_attribute *);
