--no-line: new option to ignore %line directives

For debugging preprocessed code, it is useful to be able to ignore
%line directives rather than having to filter them out externally.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

asm/nasm.c

@@ -142,6 +142,7 @@ static const struct forwrefinfo *forwref;
 
 static const struct preproc_ops *preproc;
 static StrList *include_path;
+bool pp_noline;                 /* Ignore %line directives */
 
 #define OP_NORMAL           (1U << 0)
 #define OP_PREPROCESS       (1U << 1)
@@ -839,7 +840,8 @@ enum text_options {
     OPT_PRAGMA,
     OPT_BEFORE,
     OPT_LIMIT,
-    OPT_KEEP_ALL
+    OPT_KEEP_ALL,
+    OPT_NO_LINE
 };
 struct textargs {
     const char *label;
@@ -863,6 +865,7 @@ static const struct textargs textopts[] = {
     {"before",   OPT_BEFORE,  true, 0},
     {"limit-",   OPT_LIMIT,   true, 0},
     {"keep-all", OPT_KEEP_ALL, false, 0},
+    {"no-line",  OPT_NO_LINE, false, 0},
     {NULL, OPT_BOGUS, false, 0}
 };
 
@@ -1210,6 +1213,9 @@ static bool process_arg(char *p, char *q, int pass)
                 case OPT_KEEP_ALL:
                     keep_all = true;
                     break;
+                case OPT_NO_LINE:
+                    pp_noline = true;
+                    break;
                 case OPT_HELP:
                     help(0);
                     exit(0);
@@ -2001,6 +2007,7 @@ static void help(const char xopt)
          "   --lprefix str  prepend the given string to all other symbols\n"
          "   --lpostfix str append the given string to all other symbols\n"
          "   --keep-all     output files will not be removed even if an error happens\n"
+         "   --no-line      ignore %%line directives in input\n"
          "   --limit-X val  set execution limit X\n");
 
     for (i = 0; i <= LIMIT_MAX; i++) {

asm/preproc-nop.c

@@ -86,7 +86,6 @@ static char *nop_getline(void)
     src_set_linnum(src_get_linnum() + nop_lineinc);
 
     while (1) {                 /* Loop to handle %line */
-
         p = buffer;
         while (1) {             /* Loop to handle long lines */
             q = fgets(p, bufsize - (p - buffer), nop_fp);
@@ -119,13 +118,15 @@ static char *nop_getline(void)
             int32_t ln;
             int li;
             char *nm = nasm_malloc(strlen(buffer));
-            if (sscanf(buffer + 5, "%"PRId32"+%d %s", &ln, &li, nm) == 3) {
-                src_set(ln, nm);
+            int conv = sscanf(buffer + 5, "%"PRId32"+%d %s", &ln, &li, nm);
+            if (conv >= 2) {
+                if (!pp_noline)
+                    src_set(ln, conv >= 3 ? nm : NULL);
                 nop_lineinc = li;
-                nasm_free(nm);
-                continue;
             }
             nasm_free(nm);
+            if (conv >= 2)
+                continue;
         }
         break;
     }

asm/preproc.c

@@ -3662,6 +3662,10 @@ issue_error:
         /*
          * Syntax is `%line nnn[+mmm] [filename]'
          */
+        if (unlikely(pp_noline)) {
+            free_tlist(origline);
+            return DIRECTIVE_FOUND;
+        }
         tline = tline->next;
         skip_white_(tline);
         if (!tok_type_(tline, TOK_NUMBER)) {

asm/preproc.h

@@ -43,6 +43,7 @@
 
 extern const char * const pp_directives[];
 extern const uint8_t pp_directives_len[];
+extern bool pp_noline;
 
 /* Pointer to a macro chain */
 typedef const unsigned char macros_t;

doc/changes.src

@@ -37,6 +37,9 @@ failure instead which is very slow and not easy to debug.
 \b Duplicate definitions of the same label \e{with the same value} is now
 explicitly permitted (2.14 would allow it in some circumstances.)
 
+\b Add the option \c{--no-line} to ignore \c{%line} directives in the
+source. See \k{opt-no-line} and \k{line}.
+
 \S{cl-2.14} Version 2.14
 
 \b Changed \c{-I} option semantics by adding a trailing path separator

doc/nasmdoc.src

@@ -368,10 +368,10 @@ To get further usage instructions from NASM, try typing
 
 \c nasm -h
 
-\c{--help} option is also the same.
+The option \c{--help} is an alias for the \c{-h} option.
 
-As \c{-hf}, this will also list the available output file formats, and what they
-are.
+The option \c{-hf} will also list the available output file formats,
+and what they are.
 
 If you use Linux but aren't sure whether your system is \c{a.out}
 or \c{ELF}, type
@@ -992,7 +992,14 @@ In example, running this limits the maximum line count to be 1000.
 
 \S{opt-keep-all} The \i\c{--keep-all} Option
 
-This option doesn't delete any output files even if an error happens.
+This option prevents NASM from deleting any output files even if an
+error happens.
+
+\S{opt-no-line} The \i\c{--no-line} Option
+
+If this option is given, all \i\c{%line} directives in the source code
+are ignored. This can be useful for debugging already preprocessed
+code. See \k{line}.
 
 
 \S{nasmenv} The \i\c{NASMENV} \i{Environment} Variable
@@ -3747,15 +3754,6 @@ the user.  For example:
 
 \H{otherpreproc} \i{Other Preprocessor Directives}
 
-NASM also has preprocessor directives which allow access to
-information from external sources. Currently they include:
-
-\b\c{%line} enables NASM to correctly handle the output of another
-preprocessor (see \k{line}).
-
-\b\c{%!} enables NASM to read in the value of an environment variable,
-which can then be used in your program (see \k{getenv}).
-
 \S{line} \i\c{%line} Directive
 
 The \c{%line} directive is used to notify NASM that the input line
@@ -3766,9 +3764,9 @@ directive allows NASM to output messages which indicate the line
 number of the original source file, instead of the file that is being
 read by NASM.
 
-This preprocessor directive is not generally of use to programmers,
-by may be of interest to preprocessor authors.  The usage of the
-\c{%line} preprocessor directive is as follows:
+This preprocessor directive is not generally used directly by
+programmers, but may be of interest to preprocessor authors.  The
+usage of the \c{%line} preprocessor directive is as follows:
 
 \c %line nnn[+mmm] [filename]
 
@@ -3783,6 +3781,10 @@ After reading a \c{%line} preprocessor directive, NASM will report
 all file name and line numbers relative to the values specified
 therein.
 
+If the command line option \i\c{--no-line} is given, all \c{%line}
+directives are ignored. This may be useful for debugging preprocessed
+code. See \k{opt-no-line}.
+
 
 \S{getenv} \i\c{%!}\e{variable}: Read an Environment Variable.