Improve comments and fix ascii_* attributes

runtime/doc/develop.txt

@@ -186,7 +186,7 @@ strcpy()	STRCPY()	Includes cast to (char *), for char_u * args
 strchr()	vim_strchr()	Accepts special characters
 strrchr()	vim_strrchr()	Accepts special characters
 isspace()	ascii_isspace()	Can handle characters > 128
-iswhite()	ascii_iswhite()	Only TRUE for tab and space
+iswhite()	ascii_iswhite()	Only true for tab and space
 memcpy()	mch_memmove()	Handles overlapped copies
 bcopy()		mch_memmove()	Handles overlapped copies
 memset()	vim_memset()	Uniform for all systems

src/nvim/ascii.h

@@ -9,7 +9,8 @@
 #define NVIM_ASCII_H
 
 #include <stdbool.h>
-#include "func_attr.h"
+
+#include "nvim/func_attr.h"
 
 // Definitions of various common control characters.
 
@@ -90,32 +91,36 @@
 # define PATHSEPSTR     "/"
 #endif
 
-static inline bool ascii_iswhite(int c) FUNC_ATTR_ALWAYS_INLINE FUNC_ATTR_CONST;
-static inline bool ascii_isdigit(int c) FUNC_ATTR_ALWAYS_INLINE FUNC_ATTR_CONST;
-static inline bool ascii_isxdigit(int c) FUNC_ATTR_ALWAYS_INLINE FUNC_ATTR_CONST;
-static inline bool ascii_isspace(int x) FUNC_ATTR_ALWAYS_INLINE FUNC_ATTR_CONST;
+static inline bool ascii_iswhite(int) REAL_FATTR_ALWAYS_INLINE REAL_FATTR_CONST;
+static inline bool ascii_isdigit(int) REAL_FATTR_ALWAYS_INLINE REAL_FATTR_CONST;
+static inline bool ascii_isxdigit(int) REAL_FATTR_ALWAYS_INLINE REAL_FATTR_CONST;
+static inline bool ascii_isspace(int) REAL_FATTR_ALWAYS_INLINE REAL_FATTR_CONST;
 
-/// ascii_iswhite() is used for "^" and the like. It differs from isspace()
-/// because it doesn't include <CR> and <LF> and the like.
+/// Checks if `c` is a space or tab character.
+///
+/// @see {ascii_isdigit}
 static inline bool ascii_iswhite(int c)
 {
   return c == ' ' || c == '\t';
 }
 
-/// Use our own isdigit() replacement, because on MS-Windows isdigit() returns
-/// non-zero for superscript 1.  Also avoids that isdigit() crashes for numbers
-/// below 0 and above 255.
+/// Check whether character is a decimal digit.
+///
+/// Library isdigit() function is officially locale-dependent and, for
+/// example, returns true for superscript 1 (¹) in locales where encoding
+/// contains it in lower 8 bits. Also avoids crashes in case c is below
+/// 0 or above 255: library functions are officially defined as accepting
+/// only EOF and unsigned char values (otherwise it is undefined behaviour)
+/// what may be used for some optimizations (e.g. simple `return
+/// isdigit_table[c];`).
 static inline bool ascii_isdigit(int c)
 {
   return c >= '0' && c <= '9';
 }
 
-/// Variant of isxdigit() that can handle characters > 0x100.
-/// We don't use isxdigit() here, because on some systems it also considers
-/// superscript 1 to be a digit.
+/// Checks if `c` is a hexadecimal digit, that is, one of 0-9, a-f, A-F.
 ///
-/// @param c
-/// @return TRUE if the character is a hexadecimal digit.
+/// @see {ascii_isdigit}
 static inline bool ascii_isxdigit(int c)
 {
   return (c >= '0' && c <= '9')
@@ -123,12 +128,13 @@ static inline bool ascii_isxdigit(int c)
          || (c >= 'A' && c <= 'F');
 }
 
-/// Vim has its own isspace() function, because on some machines isspace()
-/// can't handle characters above 128.
-static inline bool ascii_isspace(int x)
+/// Checks if `c` is a white-space character, that is,
+/// one of \f, \n, \r, \t, \v.
+///
+/// @see {ascii_isdigit}
+static inline bool ascii_isspace(int c)
 {
-  return (x >= 9 && x <= 13) || x == ' ';
+  return (c >= 9 && c <= 13) || c == ' ';
 }
 
-
 #endif /* NVIM_ASCII_H */

src/nvim/indent.c

@@ -706,7 +706,8 @@ int get_lisp_indent(void)
 
             if (vi_lisp || ((*that != '"') && (*that != '\'')
                 && (*that != '#') && ((*that < '0') || (*that > '9')))) {
-              while (*that && (!ascii_iswhite(*that) || quotecount || parencount)
+              while (*that
+                     && (!ascii_iswhite(*that) || quotecount || parencount)
                      && (!((*that == '(' || *that == '[')
                      && !quotecount && !parencount && vi_lisp))) {
                 if (*that == '"') {

src/nvim/ops.c

@@ -3979,8 +3979,6 @@ static int ends_in_white(linenr_T lnum)
 
   if (*s == NUL)
     return FALSE;
-  /* Don't use STRLEN() inside ascii_iswhite(), SAS/C complains: "macro
-   * invocation may call function multiple times". */
   l = STRLEN(s) - 1;
   return ascii_iswhite(s[l]);
 }

src/nvim/search.c

@@ -2921,7 +2921,7 @@ extend:
      */
     if (start_blank) {
       find_first_blank(&curwin->w_cursor);
-      c = gchar_pos(&curwin->w_cursor);         /* ascii_iswhite() is a macro */
+      c = gchar_pos(&curwin->w_cursor);
       if (ascii_iswhite(c))
         decl(&curwin->w_cursor);
     } else if (c = gchar_cursor(), !ascii_iswhite(c))

src/nvim/syntax.c

@@ -7138,9 +7138,10 @@ int highlight_changed(void)
        */
       attr = 0;
       bool colon = false;
-      for (; *p && *p != ','; ++p) {                /* parse upto comma */
-        if (ascii_iswhite(*p))                        /* ignore white space */
+      for (; *p && *p != ','; ++p) {  // parse upto comma
+        if (ascii_iswhite(*p)) {  // ignore white space
           continue;
+        }
 
         if (colon)          /* Combination with ':' is not allowed. */
           return FAIL;