check-format.pl: report #if and #elif with constant condition; improve checks on '/*'

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
(Merged from https://github.com/openssl/openssl/pull/18812)

util/check-format-test-negatives.c

@@ -30,6 +30,9 @@
 /*-
  * allow extra  SPC in format-tagged multi-line comment
  */
+/** allow extra '*' in comment opening */
+/*! allow extra '!' in comment opening */
+
 int f(void) /*
              * trailing multi-line comment
              */

util/check-format-test-positives.c

@@ -40,19 +40,21 @@
  *@ comment starting delimiter: /* inside multi-line comment
 *@ multi-line comment indent off by -1
  *X*@ no spc after leading '*' in multi-line comment, reported unless sloppy-spc
- *@0 more than two spaces after .   in comment, reported unless sloppy-spc
- *@0 more than two spaces after ?   in comment, reported unless sloppy-spc
- *@0 more than two spaces after !   in comment, reported unless sloppy-spc
+ *@0 more than two spaces after .   in comment, no more reported
+ *@0 more than two spaces after ?   in comment, no more reported
+ *@0 more than two spaces after !   in comment, no more reported
 */ /*@ multi-line comment end indent off by -1 (relative to comment start) */
 */ /*@ unexpected comment ending delimiter outside comment */
+/*- '-' for formatted comment not allowed in intra-line comment */
 /*@ comment line is 4 columns tooooooooooooooooo wide, reported unless sloppy-len */
 /*@ comment line is 5 columns toooooooooooooooooooooooooooooooooooooooooooooo wide */
+#if ~0              /*@ '#if' with constant condition */
+ #endif             /*@ indent of preproc. directive off by 1 (must be 0) */
 #define X (1 +  1)  /*@0 extra space in body, reported unless sloppy-spc */
-#define X   1       /*@ extra space before body, reported unless sloppy-spc */
- #define Y 2        /*@2 indent of preproc. directive off by 1 (must be 0) */ \
-#define Z           /*@ preprocessor directive within multi-line directive */
+#define Y   1       /*@ extra space before body, reported unless sloppy-spc */ \
+#define Z           /*@2 preprocessor directive within multi-line directive */
 typedef struct  {   /*@0 extra space in code, reported unless sloppy-spc */
-    enum {          /*@1 extra space  in comment, no more reported */
+    enum {          /*@1 extra space  in intra-line comment, no more reported */
            w = 0 /*@ hanging expr indent off by 1, or 3 for lines after '{' */
              && 1,  /*@ hanging expr indent off by 3, or -1 for leading '&&' */
          x = 1,     /*@ hanging expr indent off by -1 */
@@ -344,7 +346,7 @@ void f_looong_body()
 
     ;               /*@ 2 essentially blank lines before, if !sloppy-spc */
 }                   /*@ function body length > 200 lines */
-#if 0               /*@0 unclosed #if */
+#if X               /*@0 unclosed #if */
 struct t {          /*@0 unclosed brace at decl/block level */
     enum {          /*@0 unclosed brace at enum/expression level */
           v = (1    /*@0 unclosed parenthesis */

util/check-format.pl

@@ -606,8 +606,8 @@ while (<>) { # loop over all lines of all input files
 
     # detect end of comment, must be within multi-line comment, check if it is preceded by non-whitespace text
     if ((my ($head, $tail) = m|^(.*?)\*/(.*)$|) && $1 ne '/') { # ending comment: '*/'
-        report("neither space nor '*' before '*/'") if $head =~ m/[^*\s]$/;
-        report("missing space after '*/'") if $tail =~ m/^[^\s,;)}\]]/; # no space or ,;)}] after '*/'
+        report("missing space or '*' before '*/'") if $head =~ m/[^*\s]$/;
+        report("missing space (or ',', ';', ')', '}', ']') after '*/'") if $tail =~ m/^[^\s,;)}\]]/; # no space or ,;)}] after '*/'
         if (!($head =~ m|/\*|)) { # not begin of comment '/*', which is is handled below
             if ($in_comment == 0) {
                 report("unexpected '*/' outside comment");
@@ -632,7 +632,7 @@ while (<>) { # loop over all lines of all input files
     if (my ($head, $opt_minus, $tail) = m|^(.*?)/\*(-?)(.*)$|) { # begin of comment: '/*'
         report("missing space before '/*'")
             if $head =~ m/[^\s(\*]$/; # not space, '(', or or '*' (needed to allow '*/') before comment delimiter
-        report("missing space, '*' or '!' after '/*' or '/*-'") if $tail =~ m/^[^*\s!$self_test_exception]/;
+        report("missing space, '*', or '!' after '/*$opt_minus'") if $tail =~ m/^[^\s*!$self_test_exception]/;
         my $cmt_text = $opt_minus.$tail; # preliminary
         if ($in_comment > 0) {
             report("unexpected '/*' inside multi-line comment");
@@ -705,6 +705,8 @@ while (<>) { # loop over all lines of all input files
         }
         $in_preproc++;
         report("indent = $count != 0 for '#'") if $count != 0;
+        report("'#$preproc_directive' with constant condition")
+            if $preproc_directive =~ m/^(if|elif)$/ && m/^[\W0-9]+$/ && !$trailing_backslash;
         $preproc_if_nesting-- if $preproc_directive =~ m/^(else|elif|endif)$/;
         if ($preproc_if_nesting < 0) {
             $preproc_if_nesting = 0;
@@ -978,8 +980,6 @@ while (<>) { # loop over all lines of all input files
         if (m/(['"]|([\+\-\*\/\/%\&\|\^<>]\s*)?\W[0-9]+L?|\WNULL)\s*([\!<>=]=|[<=>])([<>]?)/ &&
             $2 eq "" && (($3 ne "<" && $3 ne "='" && $3 ne ">") || $4 eq ""));
 
-    # TODO report #if 0 and #if 1
-
     # TODO report needless use of parentheses, while
     #      macro parameters should always be in parens (except when passed on), e.g., '#define ID(x) (x)'