[SCM] GNU M4 source repository branch, branch-1_4, updated. branch-cvs-readonly-13-gaaf838a

[Eric Blake]

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- Log -----------------------------------------------------------------
commit aaf838ab071e9e33d7635d683bf5f489334c3a6b
Author: Eric Blake <address@hidden>
Date:   Wed Nov 14 15:15:31 2007 -0700

    Avoid builtin concatenation in macro arguments.
    
    * doc/m4.texinfo (Defn): Add tests.
    * src/macro.c (warn_builtin_concat): New function.
    (expand_argument): Use it to warn on more corner cases.
    * NEWS: Mention new warning.
    
    Signed-off-by: Eric Blake <address@hidden>

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog      |    8 ++++++++
 NEWS           |    8 +++++---
 doc/m4.texinfo |   37 +++++++++++++++++++++++++++++--------
 src/macro.c    |   52 +++++++++++++++++++++++++++++++++++-----------------
 4 files changed, 77 insertions(+), 28 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 068148d..ae487a0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2007-11-14  Eric Blake  <address@hidden>
+
+       Avoid builtin concatenation in macro arguments.
+       * doc/m4.texinfo (Defn): Add tests.
+       * src/macro.c (warn_builtin_concat): New function.
+       (expand_argument): Use it to warn on more corner cases.
+       * NEWS: Mention new warning.
+
 2007-11-13  Eric Blake  <address@hidden>
 
        Simplify previous patch.
diff --git a/NEWS b/NEWS
index b92630b..d988adf 100644
--- a/NEWS
+++ b/NEWS
@@ -7,11 +7,13 @@ Version 1.4.11 - ?? ??? 2007, by ????  (git version 1.4.10a-*)
 * Fix core dump in 'm4 -F file -t undefined', present since -F was
   introduced in 1.3.
 * Fix regression introduced in 1.4.9b in the `divert' builtin when more
-  than 512 kibibytes are saved in diversions on platforms like NetBSD
-  where fopen(name,"a+") seeks to the end of the file.
+  than 512 kibibytes are saved in diversions on platforms like NetBSD where
+  fopen(name,"a+") seeks to the end of the file.
 * Enhance the `defn' builtin to support concatenation of multiple text
   arguments, as required by POSIX.  However, at this time, it is not
-  possible to concatenate a builtin macro with anything else.
+  possible to concatenate a builtin macro with anything else; a warning is
+  now issued if this is attempted, although a future version of M4 may lift
+  this restriction to match other implementations.
 * Several improvements in `index', `regexp', and `patsubst' builtins to
   speed up typical Autoconf usage.
 * Memory usage is greatly reduced in recursive macros.
diff --git a/doc/m4.texinfo b/doc/m4.texinfo
index f028e3d..6caa7c3 100644
--- a/doc/m4.texinfo
+++ b/doc/m4.texinfo
@@ -2077,9 +2077,9 @@ and it is a builtin, the
 expansion is a special token, which points to the builtin's internal
 definition.  This token is only meaningful as the second argument to
 @code{define} (and @code{pushdef}), and is silently converted to an
-empty string in most other contexts.  Combining a builtin with anything
-else is not supported; a warning is issued and the builtin is omitted
-from the final expansion.
+empty string in most other contexts.  Using multiple @var{name} to
+combine a builtin with anything else is not supported; a warning is
+issued and the builtin is omitted from the final expansion.
 
 The macro @code{defn} is recognized only with parameters.
 @end deffn
@@ -2186,18 +2186,39 @@ define(defn(`divnum'), `cannot redefine a builtin 
token')
 @result{}
 divnum
 @result{}0
+define(`echo', `$@@')
address@hidden
+define(`mydivnum', echo(defn(`divnum')))
address@hidden
+mydivnum
address@hidden
 @end example
 
 Also note that @code{defn} with multiple arguments can only join text
-macros, not builtins, although a future version of @acronym{GNU} M4 may
-lift this restriction.
+macros, not builtins.  Likewise, when collecting macro arguments, a
+builtin token is preserved only when it occurs in isolation.  A future
+version of @acronym{GNU} M4 may lift these restrictions.
 
 @example
-define(`a', `A')
+define(`a', `A')define(`AA', `b')
 @result{}
-defn(`a', `defn', `a')
address@hidden:stdin:2: Warning: cannot concatenate builtin `defn'
+defn(`a', `divnum', `a')
address@hidden:stdin:2: Warning: cannot concatenate builtin `divnum'
 @result{}AA
+define(`mydivnum', defn(`divnum', `divnum'))mydivnum
address@hidden:stdin:3: Warning: cannot concatenate builtin `divnum'
address@hidden:stdin:3: Warning: cannot concatenate builtin `divnum'
address@hidden
+define(`mydivnum', defn(`divnum')defn(`divnum'))mydivnum
address@hidden:stdin:4: Warning: cannot concatenate builtin `divnum'
address@hidden:stdin:4: Warning: cannot concatenate builtin `divnum'
address@hidden
+define(`mydivnum', defn(`divnum')`a')mydivnum
address@hidden:stdin:5: Warning: cannot concatenate builtin `divnum'
address@hidden
+define(`mydivnum', `a'defn(`divnum'))mydivnum
address@hidden:stdin:6: Warning: cannot concatenate builtin `divnum'
address@hidden
 @end example
 
 @node Pushdef
diff --git a/src/macro.c b/src/macro.c
index 76f9276..9a3123a 100644
--- a/src/macro.c
+++ b/src/macro.c
@@ -125,15 +125,28 @@ expand_token (struct obstack *obs, token_type t, 
token_data *td, int line)
 }
 
 
+/*---------------------------------------------------------------.
+| Helper function to print warning about concatenating FUNC with |
+| text.                                                          |
+`---------------------------------------------------------------*/
+static void
+warn_builtin_concat (builtin_func *func)
+{
+  const builtin *bp = find_builtin_by_addr (func);
+  assert (bp);
+  M4ERROR ((warning_status, 0, "Warning: cannot concatenate builtin `%s'",
+           bp->name));
+}
+
 /*-------------------------------------------------------------------.
 | This function parses one argument to a macro call.  It expects the |
 | first left parenthesis or the separating comma to have been read   |
-| by the caller.  It skips leading whitespace, then reads and       |
+| by the caller.  It skips leading whitespace, then reads and        |
 | expands tokens, until it finds a comma or right parenthesis at the |
 | same level of parentheses.  It returns a flag indicating whether   |
-| the argument read is the last for the active macro call.  The             |
-| argument is built on the obstack OBS, indirectly through          |
-| expand_token ().  Report errors on behalf of CALLER.              |
+| the argument read is the last for the active macro call.  The      |
+| argument is built on the obstack OBS, indirectly through           |
+| expand_token ().  Report errors on behalf of CALLER.               |
 `-------------------------------------------------------------------*/
 
 static bool
@@ -141,7 +154,6 @@ expand_argument (struct obstack *obs, token_data *argp, 
const char *caller)
 {
   token_type t;
   token_data td;
-  char *text;
   int paren_level;
   const char *file = current_file;
   int line = current_line;
@@ -166,25 +178,23 @@ expand_argument (struct obstack *obs, token_data *argp, 
const char *caller)
        case TOKEN_CLOSE:
          if (paren_level == 0)
            {
-             /* The argument MUST be finished, whether we want it or not.  */
-             obstack_1grow (obs, '\0');
-             text = (char *) obstack_finish (obs);
-
-             if (TOKEN_DATA_TYPE (argp) == TOKEN_VOID)
+             if (TOKEN_DATA_TYPE (argp) == TOKEN_FUNC)
                {
-                 TOKEN_DATA_TYPE (argp) = TOKEN_TEXT;
-                 TOKEN_DATA_TEXT (argp) = text;
+                 if (obstack_object_size (obs) == 0)
+                   return t == TOKEN_COMMA;
+                 warn_builtin_concat (TOKEN_DATA_FUNC (argp));
                }
+             obstack_1grow (obs, '\0');
+             TOKEN_DATA_TYPE (argp) = TOKEN_TEXT;
+             TOKEN_DATA_TEXT (argp) = (char *) obstack_finish (obs);
              return t == TOKEN_COMMA;
            }
          /* fallthru */
        case TOKEN_OPEN:
        case TOKEN_SIMPLE:
-         text = TOKEN_DATA_TEXT (&td);
-
-         if (*text == '(')
+         if (t == TOKEN_OPEN)
            paren_level++;
-         else if (*text == ')')
+         else if (t == TOKEN_CLOSE)
            paren_level--;
          expand_token (obs, t, &td, line);
          break;
@@ -202,11 +212,19 @@ expand_argument (struct obstack *obs, token_data *argp, 
const char *caller)
          break;
 
        case TOKEN_MACDEF:
-         if (obstack_object_size (obs) == 0)
+         if (TOKEN_DATA_TYPE (argp) == TOKEN_VOID
+             && obstack_object_size (obs) == 0)
            {
              TOKEN_DATA_TYPE (argp) = TOKEN_FUNC;
              TOKEN_DATA_FUNC (argp) = TOKEN_DATA_FUNC (&td);
            }
+         else
+           {
+             if (TOKEN_DATA_TYPE (argp) == TOKEN_FUNC)
+               warn_builtin_concat (TOKEN_DATA_FUNC (argp));
+             warn_builtin_concat (TOKEN_DATA_FUNC (&td));
+             TOKEN_DATA_TYPE (argp) = TOKEN_TEXT;
+           }
          break;
 
        default:


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