diff --git a/src/spell.h b/src/spell.h
index dc102bc..b444145 100644
--- a/src/spell.h
+++ b/src/spell.h
@@ -11,33 +11,33 @@
  * spell.h: common code for spell checking, used by spell.c and spellfile.c.
  */
 
-/* Use SPELL_PRINTTREE for debugging: dump the word tree after adding a word.
- * Only use it for small word lists! */
+// Use SPELL_PRINTTREE for debugging: dump the word tree after adding a word.
+// Only use it for small word lists!
 #if 0
 # define SPELL_PRINTTREE
 #endif
 
-/* Use SPELL_COMPRESS_ALLWAYS for debugging: compress the word tree after
- * adding a word.  Only use it for small word lists! */
+// Use SPELL_COMPRESS_ALLWAYS for debugging: compress the word tree after
+// adding a word.  Only use it for small word lists!
 #if 0
 # define SPELL_COMPRESS_ALLWAYS
 #endif
 
-/* Use DEBUG_TRIEWALK to print the changes made in suggest_trie_walk() for a
- * specific word. */
+// Use DEBUG_TRIEWALK to print the changes made in suggest_trie_walk() for a
+// specific word.
 #if 0
 # define DEBUG_TRIEWALK
 #endif
 
-#define MAXWLEN 254		/* Assume max. word len is this many bytes.
-				   Some places assume a word length fits in a
-				   byte, thus it can't be above 255.
-				   Must be >= PFD_NOTSPECIAL. */
+#define MAXWLEN 254		// Assume max. word len is this many bytes.
+				// Some places assume a word length fits in a
+				// byte, thus it can't be above 255.
+				// Must be >= PFD_NOTSPECIAL.
 
-#define MAXREGIONS 8		/* Number of regions supported. */
+#define MAXREGIONS 8		// Number of regions supported.
 
-/* Type used for indexes in the word tree need to be at least 4 bytes.  If int
- * is 8 bytes we could use something smaller, but what? */
+// Type used for indexes in the word tree need to be at least 4 bytes.  If int
+// is 8 bytes we could use something smaller, but what?
 typedef int idx_T;
 
 typedef int salfirst_T;
@@ -60,74 +60,74 @@
 typedef struct slang_S slang_T;
 struct slang_S
 {
-    slang_T	*sl_next;	/* next language */
-    char_u	*sl_name;	/* language name "en", "en.rare", "nl", etc. */
-    char_u	*sl_fname;	/* name of .spl file */
-    int		sl_add;		/* TRUE if it's a .add file. */
+    slang_T	*sl_next;	// next language
+    char_u	*sl_name;	// language name "en", "en.rare", "nl", etc.
+    char_u	*sl_fname;	// name of .spl file
+    int		sl_add;		// TRUE if it's a .add file.
 
-    char_u	*sl_fbyts;	/* case-folded word bytes */
-    idx_T	*sl_fidxs;	/* case-folded word indexes */
-    char_u	*sl_kbyts;	/* keep-case word bytes */
-    idx_T	*sl_kidxs;	/* keep-case word indexes */
-    char_u	*sl_pbyts;	/* prefix tree word bytes */
-    idx_T	*sl_pidxs;	/* prefix tree word indexes */
+    char_u	*sl_fbyts;	// case-folded word bytes
+    idx_T	*sl_fidxs;	// case-folded word indexes
+    char_u	*sl_kbyts;	// keep-case word bytes
+    idx_T	*sl_kidxs;	// keep-case word indexes
+    char_u	*sl_pbyts;	// prefix tree word bytes
+    idx_T	*sl_pidxs;	// prefix tree word indexes
 
-    char_u	*sl_info;	/* infotext string or NULL */
+    char_u	*sl_info;	// infotext string or NULL
 
     char_u	sl_regions[MAXREGIONS * 2 + 1];
-				/* table with up to 8 region names plus NUL */
+				// table with up to 8 region names plus NUL
 
-    char_u	*sl_midword;	/* MIDWORD string or NULL */
+    char_u	*sl_midword;	// MIDWORD string or NULL
 
-    hashtab_T	sl_wordcount;	/* hashtable with word count, wordcount_T */
+    hashtab_T	sl_wordcount;	// hashtable with word count, wordcount_T
 
-    int		sl_compmax;	/* COMPOUNDWORDMAX (default: MAXWLEN) */
-    int		sl_compminlen;	/* COMPOUNDMIN (default: 0) */
-    int		sl_compsylmax;	/* COMPOUNDSYLMAX (default: MAXWLEN) */
-    int		sl_compoptions;	/* COMP_* flags */
-    garray_T	sl_comppat;	/* CHECKCOMPOUNDPATTERN items */
-    regprog_T	*sl_compprog;	/* COMPOUNDRULE turned into a regexp progrm
-				 * (NULL when no compounding) */
-    char_u	*sl_comprules;	/* all COMPOUNDRULE concatenated (or NULL) */
-    char_u	*sl_compstartflags; /* flags for first compound word */
-    char_u	*sl_compallflags; /* all flags for compound words */
-    char_u	sl_nobreak;	/* When TRUE: no spaces between words */
-    char_u	*sl_syllable;	/* SYLLABLE repeatable chars or NULL */
-    garray_T	sl_syl_items;	/* syllable items */
+    int		sl_compmax;	// COMPOUNDWORDMAX (default: MAXWLEN)
+    int		sl_compminlen;	// COMPOUNDMIN (default: 0)
+    int		sl_compsylmax;	// COMPOUNDSYLMAX (default: MAXWLEN)
+    int		sl_compoptions;	// COMP_* flags
+    garray_T	sl_comppat;	// CHECKCOMPOUNDPATTERN items
+    regprog_T	*sl_compprog;	// COMPOUNDRULE turned into a regexp progrm
+				// (NULL when no compounding)
+    char_u	*sl_comprules;	// all COMPOUNDRULE concatenated (or NULL)
+    char_u	*sl_compstartflags; // flags for first compound word
+    char_u	*sl_compallflags; // all flags for compound words
+    char_u	sl_nobreak;	// When TRUE: no spaces between words
+    char_u	*sl_syllable;	// SYLLABLE repeatable chars or NULL
+    garray_T	sl_syl_items;	// syllable items
 
-    int		sl_prefixcnt;	/* number of items in "sl_prefprog" */
-    regprog_T	**sl_prefprog;	/* table with regprogs for prefixes */
+    int		sl_prefixcnt;	// number of items in "sl_prefprog"
+    regprog_T	**sl_prefprog;	// table with regprogs for prefixes
 
-    garray_T	sl_rep;		/* list of fromto_T entries from REP lines */
-    short	sl_rep_first[256];  /* indexes where byte first appears, -1 if
-				       there is none */
-    garray_T	sl_sal;		/* list of salitem_T entries from SAL lines */
-    salfirst_T	sl_sal_first[256];  /* indexes where byte first appears, -1 if
-				       there is none */
-    int		sl_followup;	/* SAL followup */
-    int		sl_collapse;	/* SAL collapse_result */
-    int		sl_rem_accents;	/* SAL remove_accents */
-    int		sl_sofo;	/* SOFOFROM and SOFOTO instead of SAL items:
-				 * "sl_sal_first" maps chars, when has_mbyte
-				 * "sl_sal" is a list of wide char lists. */
-    garray_T	sl_repsal;	/* list of fromto_T entries from REPSAL lines */
-    short	sl_repsal_first[256];  /* sl_rep_first for REPSAL lines */
-    int		sl_nosplitsugs;	/* don't suggest splitting a word */
-    int		sl_nocompoundsugs; /* don't suggest compounding */
+    garray_T	sl_rep;		// list of fromto_T entries from REP lines
+    short	sl_rep_first[256];  // indexes where byte first appears, -1 if
+				    // there is none
+    garray_T	sl_sal;		// list of salitem_T entries from SAL lines
+    salfirst_T	sl_sal_first[256];  // indexes where byte first appears, -1 if
+				    // there is none
+    int		sl_followup;	// SAL followup
+    int		sl_collapse;	// SAL collapse_result
+    int		sl_rem_accents;	// SAL remove_accents
+    int		sl_sofo;	// SOFOFROM and SOFOTO instead of SAL items:
+				// "sl_sal_first" maps chars, when has_mbyte
+				// "sl_sal" is a list of wide char lists.
+    garray_T	sl_repsal;	// list of fromto_T entries from REPSAL lines
+    short	sl_repsal_first[256];  // sl_rep_first for REPSAL lines
+    int		sl_nosplitsugs;	// don't suggest splitting a word
+    int		sl_nocompoundsugs; // don't suggest compounding
 
-    /* Info from the .sug file.  Loaded on demand. */
-    time_t	sl_sugtime;	/* timestamp for .sug file */
-    char_u	*sl_sbyts;	/* soundfolded word bytes */
-    idx_T	*sl_sidxs;	/* soundfolded word indexes */
-    buf_T	*sl_sugbuf;	/* buffer with word number table */
-    int		sl_sugloaded;	/* TRUE when .sug file was loaded or failed to
-				   load */
+    // Info from the .sug file.  Loaded on demand.
+    time_t	sl_sugtime;	// timestamp for .sug file
+    char_u	*sl_sbyts;	// soundfolded word bytes
+    idx_T	*sl_sidxs;	// soundfolded word indexes
+    buf_T	*sl_sugbuf;	// buffer with word number table
+    int		sl_sugloaded;	// TRUE when .sug file was loaded or failed to
+				// load
 
-    int		sl_has_map;	/* TRUE if there is a MAP line */
-    hashtab_T	sl_map_hash;	/* MAP for multi-byte chars */
-    int		sl_map_array[256]; /* MAP for first 256 chars */
-    hashtab_T	sl_sounddone;	/* table with soundfolded words that have
-				   handled, see add_sound_suggest() */
+    int		sl_has_map;	// TRUE if there is a MAP line
+    hashtab_T	sl_map_hash;	// MAP for multi-byte chars
+    int		sl_map_array[256]; // MAP for first 256 chars
+    hashtab_T	sl_sounddone;	// table with soundfolded words that have
+				// handled, see add_sound_suggest()
 };
 
 #ifdef VMS
@@ -140,94 +140,94 @@
 # define SPL_FNAME_ASCII ".ascii."
 #endif
 
-/* Flags used for a word.  Only the lowest byte can be used, the region byte
- * comes above it. */
-#define WF_REGION   0x01	/* region byte follows */
-#define WF_ONECAP   0x02	/* word with one capital (or all capitals) */
-#define WF_ALLCAP   0x04	/* word must be all capitals */
-#define WF_RARE	    0x08	/* rare word */
-#define WF_BANNED   0x10	/* bad word */
-#define WF_AFX	    0x20	/* affix ID follows */
-#define WF_FIXCAP   0x40	/* keep-case word, allcap not allowed */
-#define WF_KEEPCAP  0x80	/* keep-case word */
+// Flags used for a word.  Only the lowest byte can be used, the region byte
+// comes above it.
+#define WF_REGION   0x01	// region byte follows
+#define WF_ONECAP   0x02	// word with one capital (or all capitals)
+#define WF_ALLCAP   0x04	// word must be all capitals
+#define WF_RARE	    0x08	// rare word
+#define WF_BANNED   0x10	// bad word
+#define WF_AFX	    0x20	// affix ID follows
+#define WF_FIXCAP   0x40	// keep-case word, allcap not allowed
+#define WF_KEEPCAP  0x80	// keep-case word
 
 #define WF_CAPMASK (WF_ONECAP | WF_ALLCAP | WF_KEEPCAP | WF_FIXCAP)
 
-/* for <flags2>, shifted up one byte to be used in wn_flags */
-#define WF_HAS_AFF  0x0100	/* word includes affix */
-#define WF_NEEDCOMP 0x0200	/* word only valid in compound */
-#define WF_NOSUGGEST 0x0400	/* word not to be suggested */
-#define WF_COMPROOT 0x0800	/* already compounded word, COMPOUNDROOT */
-#define WF_NOCOMPBEF 0x1000	/* no compounding before this word */
-#define WF_NOCOMPAFT 0x2000	/* no compounding after this word */
+// for <flags2>, shifted up one byte to be used in wn_flags
+#define WF_HAS_AFF  0x0100	// word includes affix
+#define WF_NEEDCOMP 0x0200	// word only valid in compound
+#define WF_NOSUGGEST 0x0400	// word not to be suggested
+#define WF_COMPROOT 0x0800	// already compounded word, COMPOUNDROOT
+#define WF_NOCOMPBEF 0x1000	// no compounding before this word
+#define WF_NOCOMPAFT 0x2000	// no compounding after this word
 
-/* flags for <pflags> */
-#define WFP_RARE	    0x01	/* rare prefix */
-#define WFP_NC		    0x02	/* prefix is not combining */
-#define WFP_UP		    0x04	/* to-upper prefix */
-#define WFP_COMPPERMIT	    0x08	/* prefix with COMPOUNDPERMITFLAG */
-#define WFP_COMPFORBID	    0x10	/* prefix with COMPOUNDFORBIDFLAG */
+// flags for <pflags>
+#define WFP_RARE	    0x01	// rare prefix
+#define WFP_NC		    0x02	// prefix is not combining
+#define WFP_UP		    0x04	// to-upper prefix
+#define WFP_COMPPERMIT	    0x08	// prefix with COMPOUNDPERMITFLAG
+#define WFP_COMPFORBID	    0x10	// prefix with COMPOUNDFORBIDFLAG
 
-/* Flags for postponed prefixes in "sl_pidxs".  Must be above affixID (one
- * byte) and prefcondnr (two bytes). */
-#define WF_RAREPFX  (WFP_RARE << 24)	/* rare postponed prefix */
-#define WF_PFX_NC   (WFP_NC << 24)	/* non-combining postponed prefix */
-#define WF_PFX_UP   (WFP_UP << 24)	/* to-upper postponed prefix */
-#define WF_PFX_COMPPERMIT (WFP_COMPPERMIT << 24) /* postponed prefix with
-						  * COMPOUNDPERMITFLAG */
-#define WF_PFX_COMPFORBID (WFP_COMPFORBID << 24) /* postponed prefix with
-						  * COMPOUNDFORBIDFLAG */
+// Flags for postponed prefixes in "sl_pidxs".  Must be above affixID (one
+// byte) and prefcondnr (two bytes).
+#define WF_RAREPFX  (WFP_RARE << 24)	// rare postponed prefix
+#define WF_PFX_NC   (WFP_NC << 24)	// non-combining postponed prefix
+#define WF_PFX_UP   (WFP_UP << 24)	// to-upper postponed prefix
+#define WF_PFX_COMPPERMIT (WFP_COMPPERMIT << 24) // postponed prefix with
+						 // COMPOUNDPERMITFLAG
+#define WF_PFX_COMPFORBID (WFP_COMPFORBID << 24) // postponed prefix with
+						 // COMPOUNDFORBIDFLAG
 
-/* flags for <compoptions> */
-#define COMP_CHECKDUP		1	/* CHECKCOMPOUNDDUP */
-#define COMP_CHECKREP		2	/* CHECKCOMPOUNDREP */
-#define COMP_CHECKCASE		4	/* CHECKCOMPOUNDCASE */
-#define COMP_CHECKTRIPLE	8	/* CHECKCOMPOUNDTRIPLE */
+// flags for <compoptions>
+#define COMP_CHECKDUP		1	// CHECKCOMPOUNDDUP
+#define COMP_CHECKREP		2	// CHECKCOMPOUNDREP
+#define COMP_CHECKCASE		4	// CHECKCOMPOUNDCASE
+#define COMP_CHECKTRIPLE	8	// CHECKCOMPOUNDTRIPLE
 
-/* Info from "REP", "REPSAL" and "SAL" entries in ".aff" file used in si_rep,
- * si_repsal, sl_rep, and si_sal.  Not for sl_sal!
- * One replacement: from "ft_from" to "ft_to". */
+// Info from "REP", "REPSAL" and "SAL" entries in ".aff" file used in si_rep,
+// si_repsal, sl_rep, and si_sal.  Not for sl_sal!
+// One replacement: from "ft_from" to "ft_to".
 typedef struct fromto_S
 {
     char_u	*ft_from;
     char_u	*ft_to;
 } fromto_T;
 
-/* Info from "SAL" entries in ".aff" file used in sl_sal.
- * The info is split for quick processing by spell_soundfold().
- * Note that "sm_oneof" and "sm_rules" point into sm_lead. */
+// Info from "SAL" entries in ".aff" file used in sl_sal.
+// The info is split for quick processing by spell_soundfold().
+// Note that "sm_oneof" and "sm_rules" point into sm_lead.
 typedef struct salitem_S
 {
-    char_u	*sm_lead;	/* leading letters */
-    int		sm_leadlen;	/* length of "sm_lead" */
-    char_u	*sm_oneof;	/* letters from () or NULL */
-    char_u	*sm_rules;	/* rules like ^, $, priority */
-    char_u	*sm_to;		/* replacement. */
-    int		*sm_lead_w;	/* wide character copy of "sm_lead" */
-    int		*sm_oneof_w;	/* wide character copy of "sm_oneof" */
-    int		*sm_to_w;	/* wide character copy of "sm_to" */
+    char_u	*sm_lead;	// leading letters
+    int		sm_leadlen;	// length of "sm_lead"
+    char_u	*sm_oneof;	// letters from () or NULL
+    char_u	*sm_rules;	// rules like ^, $, priority
+    char_u	*sm_to;		// replacement.
+    int		*sm_lead_w;	// wide character copy of "sm_lead"
+    int		*sm_oneof_w;	// wide character copy of "sm_oneof"
+    int		*sm_to_w;	// wide character copy of "sm_to"
 } salitem_T;
 
-/* Values for SP_*ERROR are negative, positive values are used by
- * read_cnt_string(). */
-#define	SP_TRUNCERROR	-1	/* spell file truncated error */
-#define	SP_FORMERROR	-2	/* format error in spell file */
-#define SP_OTHERERROR	-3	/* other error while reading spell file */
+// Values for SP_*ERROR are negative, positive values are used by
+// read_cnt_string().
+#define	SP_TRUNCERROR	-1	// spell file truncated error
+#define	SP_FORMERROR	-2	// format error in spell file
+#define SP_OTHERERROR	-3	// other error while reading spell file
 
 /*
  * Structure used in "b_langp", filled from 'spelllang'.
  */
 typedef struct langp_S
 {
-    slang_T	*lp_slang;	/* info for this language */
-    slang_T	*lp_sallang;	/* language used for sound folding or NULL */
-    slang_T	*lp_replang;	/* language used for REP items or NULL */
-    int		lp_region;	/* bitmask for region or REGION_ALL */
+    slang_T	*lp_slang;	// info for this language
+    slang_T	*lp_sallang;	// language used for sound folding or NULL
+    slang_T	*lp_replang;	// language used for REP items or NULL
+    int		lp_region;	// bitmask for region or REGION_ALL
 } langp_T;
 
 #define LANGP_ENTRY(ga, i)	(((langp_T *)(ga).ga_data) + (i))
 
-#define VIMSUGMAGIC "VIMsug"	/* string at start of Vim .sug file */
+#define VIMSUGMAGIC "VIMsug"	// string at start of Vim .sug file
 #define VIMSUGMAGICL 6
 #define VIMSUGVERSION 1
 
@@ -237,10 +237,10 @@
  */
 typedef struct spelltab_S
 {
-    char_u  st_isw[256];	/* flags: is word char */
-    char_u  st_isu[256];	/* flags: is uppercase char */
-    char_u  st_fold[256];	/* chars: folded case */
-    char_u  st_upper[256];	/* chars: upper case */
+    char_u  st_isw[256];	// flags: is word char
+    char_u  st_isu[256];	// flags: is uppercase char
+    char_u  st_fold[256];	// chars: folded case
+    char_u  st_upper[256];	// chars: upper case
 } spelltab_T;
 
 /*
@@ -249,11 +249,11 @@
  * These must not be called with negative number!
  */
 #if defined(HAVE_WCHAR_H)
-# include <wchar.h>	    /* for towupper() and towlower() */
+# include <wchar.h>	    // for towupper() and towlower()
 #endif
-/* Multi-byte implementation.  For Unicode we can call utf_*(), but don't do
- * that for ASCII, because we don't want to use 'casemap' here.  Otherwise use
- * the "w" library function for characters above 255 if available. */
+// Multi-byte implementation.  For Unicode we can call utf_*(), but don't do
+// that for ASCII, because we don't want to use 'casemap' here.  Otherwise use
+// the "w" library function for characters above 255 if available.
 #ifdef HAVE_TOWLOWER
 # define SPELL_TOFOLD(c) (enc_utf8 && (c) >= 128 ? utf_fold(c) \
 	    : (c) < 256 ? (int)spelltab.st_fold[c] : (int)towlower(c))
@@ -279,8 +279,8 @@
 #endif
 
 #ifdef FEAT_SPELL
-/* First language that is loaded, start of the linked list of loaded
- * languages. */
+// First language that is loaded, start of the linked list of loaded
+// languages.
 # ifdef IN_SPELL_C
 #  define SPELL_EXTERN
 #  define SPELL_INIT(x) x
@@ -291,7 +291,7 @@
 
 SPELL_EXTERN slang_T	*first_lang SPELL_INIT(= NULL);
 
-/* file used for "zG" and "zW" */
+// file used for "zG" and "zW"
 SPELL_EXTERN char_u	*int_wordlist SPELL_INIT(= NULL);
 
 
@@ -307,15 +307,15 @@
 
 typedef struct wordcount_S
 {
-    short_u	wc_count;	    /* nr of times word was seen */
-    char_u	wc_word[1];	    /* word, actually longer */
+    short_u	wc_count;	    // nr of times word was seen
+    char_u	wc_word[1];	    // word, actually longer
 } wordcount_T;
 
 #define WC_KEY_OFF  offsetof(wordcount_T, wc_word)
 #define HI2WC(hi)     ((wordcount_T *)((hi)->hi_key - WC_KEY_OFF))
 #define MAXWORDCOUNT 0xffff
 
-/* Remember what "z?" replaced. */
+// Remember what "z?" replaced.
 SPELL_EXTERN char_u	*repl_from SPELL_INIT(= NULL);
 SPELL_EXTERN char_u	*repl_to SPELL_INIT(= NULL);
 #endif