FYI: fix PR macros/13205

Tom Tromey
2012-05-16T20:28:57Z

I'm checking this in.

This adds support for the special macros __FILE__ and __LINE__ to gdb.
This is PR 13250.

This is a bit tricky because the macro definitions change depending on
context. So, I needed some special logic for this.

Built and regtested on x86-64 Fedora 16.

GCC actually has a number of other special macros. I did not implement
these, but I chose an implementation approach that makes it easy to add
them in the future if desired. In particular it is trivial to expand
macro_special_kind.

Tom

b/gdb/ChangeLog:
2012-05-16 Tom Tromey <tromey@redhat.com>

PR macros/13205:
* macrotab.h: (macro_define_special): Declare.
(enum macro_special_kind): New.
(struct macro_definition) <argc, replacement>: Update comments.
* macrotab.c (new_macro_definition): Unconditionally set 'argc'.
(macro_define_object_internal): New function.
(macro_define_object): Use it.
(macro_define_special): New function.
(fixup_definition): New function.
(macro_lookup_definition, foreach_macro_in_scope)
(foreach_macro): Use fixup_definition.
* macroexp.h (macro_stringify): Declare.
* macroexp.c (free_buffer_return_text): New function.
(stringify): Constify "arg".
(macro_stringify): New function.
* dwarf2read.c (macro_start_file): Call macro_define_special.

b/gdb/testsuite/ChangeLog:
2012-05-16 Tom Tromey <tromey@redhat.com>

* gdb.base/macscp1.c (macscp_expr): Add comment.
* gdb.base/macscp.exp: Test __FILE__ and __LINE__.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index f06dea6..f89742b 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -15572,9 +15572,12 @@ macro_start_file (int file, int line,
objfile->macro_cache);

if (! current_file)
- /* If we have no current file, then this must be the start_file
- directive for the compilation unit's main source file. */
- current_file = macro_set_main (pending_macros, full_name);
+ {
+ /* If we have no current file, then this must be the start_file
+ directive for the compilation unit's main source file. */
+ current_file = macro_set_main (pending_macros, full_name);
+ macro_define_special (pending_macros);
+ }
else
current_file = macro_include (current_file, line, full_name);

diff --git a/gdb/macroexp.c b/gdb/macroexp.c
index d5e4e40..22b904e 100644
--- a/gdb/macroexp.c
+++ b/gdb/macroexp.c
@@ -113,6 +113,17 @@ free_buffer (struct macro_buffer *b)
xfree (b->text);
}

+/* Like free_buffer, but return the text as an xstrdup()d string.
+ This only exists to try to make the API relatively clean. */
+
+static char *
+free_buffer_return_text (struct macro_buffer *b)
+{
+ gdb_assert (! b->shared);
+ gdb_assert (b->size);
+ /* Nothing to do. */
+ return b->text;
+}

/* A cleanup function for macro buffers. */
static void
@@ -639,7 +650,7 @@ append_tokens_without_splicing (struct macro_buffer *dest,
stringify; it is LEN bytes long. */

static void
-stringify (struct macro_buffer *dest, char *arg, int len)
+stringify (struct macro_buffer *dest, const char *arg, int len)
{
/* Trim initial whitespace from ARG. */
while (len > 0 && macro_is_whitespace (*arg))
@@ -682,6 +693,21 @@ stringify (struct macro_buffer *dest, char *arg, int len)
dest->last_token = dest->len;
}

+/* See macroexp.h. */
+
+char *
+macro_stringify (const char *str)
+{
+ struct macro_buffer buffer;
+ int len = strlen (str);
+ char *result;
+
+ init_buffer (&buffer, len);
+ stringify (&buffer, str, len);
+
+ return free_buffer_return_text (&buffer);
+}
+
\f
/* Expanding macros! */

diff --git a/gdb/macroexp.h b/gdb/macroexp.h
index 289619e..dba03f6 100644
--- a/gdb/macroexp.h
+++ b/gdb/macroexp.h
@@ -91,4 +91,9 @@ int macro_is_identifier_nondigit (int c);
int macro_is_digit (int c);

+/* Stringify STR according to C rules and return an xmalloc'd pointer
+ to the result. */
+
+char *macro_stringify (const char *str);
+
#endif /* MACROEXP_H */
diff --git a/gdb/macrotab.c b/gdb/macrotab.c
index 7428839..e65e5dc 100644
--- a/gdb/macrotab.c
+++ b/gdb/macrotab.c
@@ -28,6 +28,7 @@
#include "gdb_assert.h"
#include "bcache.h"
#include "complaints.h"
+#include "macroexp.h"

\f
/* The macro table structure. */
@@ -565,6 +566,7 @@ new_macro_definition (struct macro_table *t,
d->table = t;
d->kind = kind;
d->replacement = macro_bcache_str (t, replacement);
+ d->argc = argc;

if (kind == macro_function_like)
{
@@ -579,7 +581,6 @@ new_macro_definition (struct macro_table *t,

/* Now bcache the array of argument pointers itself. */
d->argv = macro_bcache (t, cached_argv, cached_argv_size);
- d->argc = argc;
}

/* We don't bcache the entire definition structure because it's got
@@ -742,10 +743,12 @@ check_for_redefinition (struct macro_source_file *source, int line,
return 0;
}

+/* A helper function to define a new object-like macro. */

-void
-macro_define_object (struct macro_source_file *source, int line,
- const char *name, const char *replacement)
+static void
+macro_define_object_internal (struct macro_source_file *source, int line,
+ const char *name, const char *replacement,
+ enum macro_special_kind kind)
{
struct macro_table *t = source->table;
struct macro_key *k = NULL;
@@ -771,10 +774,28 @@ macro_define_object (struct macro_source_file *source, int line,
return;

k = new_macro_key (t, name, source, line);
- d = new_macro_definition (t, macro_object_like, 0, 0, replacement);
+ d = new_macro_definition (t, macro_object_like, kind, 0, replacement);
splay_tree_insert (t->definitions, (splay_tree_key) k, (splay_tree_value) d);
}

+void
+macro_define_object (struct macro_source_file *source, int line,
+ const char *name, const char *replacement)
+{
+ macro_define_object_internal (source, line, name, replacement,
+ macro_ordinary);
+}
+
+/* See macrotab.h. */
+
+void
+macro_define_special (struct macro_table *table)
+{
+ macro_define_object_internal (table->main_source, -1, "__FILE__", "",
+ macro_FILE);
+ macro_define_object_internal (table->main_source, -1, "__LINE__", "",
+ macro_LINE);
+}

void
macro_define_function (struct macro_source_file *source, int line,
@@ -859,6 +880,36 @@ macro_undef (struct macro_source_file *source, int line,
}
}

+/* A helper function that rewrites the definition of a special macro,
+ when needed. */
+
+static struct macro_definition *
+fixup_definition (const char *filename, int line, struct macro_definition *def)
+{
+ static char *saved_expansion;
+
+ if (saved_expansion)
+ {
+ xfree (saved_expansion);
+ saved_expansion = NULL;
+ }
+
+ if (def->kind == macro_object_like)
+ {
+ if (def->argc == macro_FILE)
+ {
+ saved_expansion = macro_stringify (filename);
+ def->replacement = saved_expansion;
+ }
+ else if (def->argc == macro_LINE)
+ {
+ saved_expansion = xstrprintf ("%d", line);
+ def->replacement = saved_expansion;
+ }
+ }
+
+ return def;
+}

struct macro_definition *
macro_lookup_definition (struct macro_source_file *source,
@@ -867,7 +918,8 @@ macro_lookup_definition (struct macro_source_file *source,
splay_tree_node n = find_definition (name, source, line);

if (n)
- return (struct macro_definition *) n->value;
+ return fixup_definition (source->filename, line,
+ (struct macro_definition *) n->value);
else
return 0;
}
@@ -910,7 +962,9 @@ foreach_macro (splay_tree_node node, void *arg)
{
struct macro_for_each_data *datum = (struct macro_for_each_data *) arg;
struct macro_key *key = (struct macro_key *) node->key;
- struct macro_definition *def = (struct macro_definition *) node->value;
+ struct macro_definition *def
+ = fixup_definition (key->start_file->filename, key->start_line,
+ (struct macro_definition *) node->value);

(*datum->fn) (key->name, def, key->start_file, key->start_line,
datum->user_data);
@@ -936,7 +990,9 @@ foreach_macro_in_scope (splay_tree_node node, void *info)
{
struct macro_for_each_data *datum = (struct macro_for_each_data *) info;
struct macro_key *key = (struct macro_key *) node->key;
- struct macro_definition *def = (struct macro_definition *) node->value;
+ struct macro_definition *def
+ = fixup_definition (datum->file->filename, datum->line,
+ (struct macro_definition *) node->value);

/* See if this macro is defined before the passed-in line, and
extends past that line. */
diff --git a/gdb/macrotab.h b/gdb/macrotab.h
index 8316cc3..92f1656 100644
--- a/gdb/macrotab.h
+++ b/gdb/macrotab.h
@@ -212,6 +212,10 @@ struct macro_source_file *macro_include (struct macro_source_file *source,
int line,
const char *included);

+/* Define any special macros, like __FILE__ or __LINE__. This should
+ be called once, on the main source file. */
+
+void macro_define_special (struct macro_table *table);

/* Find any source file structure for a file named NAME, either
included into SOURCE, or SOURCE itself. Return zero if we have
@@ -261,6 +265,17 @@ enum macro_kind
macro_function_like
};

+/* Different kinds of special macros. */
+
+enum macro_special_kind
+{
+ /* Ordinary. */
+ macro_ordinary,
+ /* The special macro __FILE__. */
+ macro_FILE,
+ /* The special macro __LINE__. */
+ macro_LINE
+};

/* A preprocessor symbol definition. */
struct macro_definition
@@ -273,12 +288,17 @@ struct macro_definition

/* If `kind' is `macro_function_like', the number of arguments it
takes, and their names. The names, and the array of pointers to
- them, are in the table's bcache, if it has one. */
- int argc : 31;
+ them, are in the table's bcache, if it has one. If `kind' is
+ `macro_object_like', then this is actually a `macro_special_kind'
+ describing the macro. */
+ int argc : 30;
const char * const *argv;

- /* The replacement string (body) of the macro. This is in the
- table's bcache, if it has one. */
+ /* The replacement string (body) of the macro. For ordinary macros,
+ this is in the table's bcache, if it has one. For special macros
+ like __FILE__, this value is only valid until the next use of any
+ special macro definition; that is, it is reset each time any
+ special macro is looked up or iterated over. */
const char *replacement;
};

diff --git a/gdb/testsuite/gdb.base/macscp.exp b/gdb/testsuite/gdb.base/macscp.exp
index fa2173a..44a526b 100644
--- a/gdb/testsuite/gdb.base/macscp.exp
+++ b/gdb/testsuite/gdb.base/macscp.exp
@@ -227,6 +227,10 @@ list_and_check_macro macscp3_2 WHERE {macscp3.h macscp1.c {before macscp3_2}}
gdb_test "info macro FROM_COMMANDLINE" \
"Defined at \[^\r\n\]*:0\r\n-DFROM_COMMANDLINE=ARG"

+gdb_test "info macro __FILE__" "#define __FILE__ \".*macscp3.h\"" \
+ "info macro __FILE__ before running"
+gdb_test "info macro __LINE__" "#define __LINE__ 26" \
+ "info macro __LINE__ before running"

# Although GDB's macro table structures distinguish between multiple
# #inclusions of the same file, GDB's other structures don't. So the
@@ -466,7 +470,7 @@ gdb_test "print MACRO_TO_EXPAND" \
" = 0" \
"print expression with macro after removing override"

-gdb_test "next" "foo = 2;" "next to definition 2"
+gdb_test "next" "foo = 2;.*" "next to definition 2"

gdb_test "print MACRO_TO_EXPAND" \
"No symbol \"MACRO_TO_EXPAND\" in current context\." \
@@ -673,3 +677,7 @@ gdb_test_no_output "macro define si_addr fields.fault.si_addr" \
gdb_test "macro expand siginfo.si_addr" \
"expands to: siginfo.fields.fault.si_addr" \
"macro expand siginfo.si_addr"
+
+gdb_test "print __FILE__" " = \".*macscp1.c\""
+gdb_test "print __LINE__" \
+ " = [gdb_get_line_number {stopping point for line test}]"
diff --git a/gdb/testsuite/gdb.base/macscp1.c b/gdb/testsuite/gdb.base/macscp1.c
index e754b26..b1eb0b4 100644
--- a/gdb/testsuite/gdb.base/macscp1.c
+++ b/gdb/testsuite/gdb.base/macscp1.c
@@ -91,7 +91,7 @@ macscp_expr (void)
#define MACRO_TO_EXPAND foo
foo = 1;
#undef MACRO_TO_EXPAND
- foo = 2;
+ foo = 2; /* stopping point for line test */
}

#define TWENTY_THREE 23