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Fix issues with unrepresentable column numbers (PR c++/77949)

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PR c++/77949 identifies an ICE when the C++ frontend attempts to emit a
fix-it hint inserting a missing semicolon at column 4097 of a source file.

This column value exceeds LINE_MAP_MAX_COLUMN_NUMBER and hence isn't
representable using a location_t.

Attempting to do so leads to these problems, which this patch fixes:

(a) when encountering a column number > LINE_MAP_MAX_COLUMN_NUMBER we
create a new linemap with m_column_and_range_bits == 0, but
linemap_position_for_column doesn't check for this, and hence can emit
a bogus location_t value that's calculated relative to the previous
linemap start, but which will be decoded relative to the new linemap,
leading to very large incorrect line values.

(b) when encountering a column number that can't be represented, and
for which the linemap was pre-existing, the code would hit this assertion:
  if (linemap_assert_fails (column < (1u << map->m_column_and_range_bits)))
around a bail-out condition.  The patch replaces this assertion with a
simple conditional, to stop the ICE when this occurs, and fixes the
bit count (effective column bits, vs column+range bits)

(c) the C++ frontend wasn't checking for failure of
linemap_position_for_loc_and_offset when considering emitting the fix-it
hint.  The patch adds a conditional, so that no fix-it hint is emitted
if the location is bogus.

gcc/cp/ChangeLog:
	PR c++/77949
	* parser.c (cp_parser_class_specifier_1): Only suggest inserting
	a missing semicolon if we have a valid insertion location for
	the fix-it hint.

gcc/ChangeLog:
	PR c++/77949
	* input.c (selftest::test_accessing_ordinary_linemaps): Verify
	that we correctly handle column numbers greater than
	LINE_MAP_MAX_COLUMN_NUMBER.

gcc/testsuite/ChangeLog:
	PR c++/77949
	* g++.dg/diagnostic/pr77949.C: New test case.

libcpp/ChangeLog:
	PR c++/77949
	* line-map.c (linemap_position_for_column): When calling
	linemap_start_line, detect if a new linemap was created with
	0 column bits, and bail out early if this is the case.
	(linemap_position_for_loc_and_offset): Replace overzealous
	linemap_assert_fails with a simple conditional; use correct
	bit count.

From-SVN: r244292
This commit is contained in:
David Malcolm 2017-01-10 21:54:09 +00:00 committed by David Malcolm
parent 6fcb740ac4
commit b9f4757f8e
8 changed files with 84 additions and 2 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
2017-01-10 David Malcolm <dmalcolm@redhat.com>
PR c++/77949
* input.c (selftest::test_accessing_ordinary_linemaps): Verify
that we correctly handle column numbers greater than
LINE_MAP_MAX_COLUMN_NUMBER.
2017-01-10 Martin Sebor <msebor@redhat.com>
PR tree-optimization/78775

7
gcc/cp/ChangeLog
View File

@ -1,3 +1,10 @@
2017-01-10 David Malcolm <dmalcolm@redhat.com>
PR c++/77949
* parser.c (cp_parser_class_specifier_1): Only suggest inserting
a missing semicolon if we have a valid insertion location for
the fix-it hint.
2017-01-10 Jason Merrill <jason@redhat.com>
FI 20, decomposition declaration with parenthesized initializer.

5
gcc/cp/parser.c
View File

@ -22164,7 +22164,10 @@ cp_parser_class_specifier_1 (cp_parser* parser)
next_loc = linemap_position_for_loc_and_offset (line_table, loc, 1);
rich_location richloc (line_table, next_loc);
richloc.add_fixit_insert_before (next_loc, ";");
/* If we successfully offset the location, suggest the fix-it. */
if (next_loc != loc)
richloc.add_fixit_insert_before (next_loc, ";");
if (CLASSTYPE_DECLARED_CLASS (type))
error_at_rich_loc (&richloc,

26
gcc/input.c
View File

@ -1699,6 +1699,22 @@ test_accessing_ordinary_linemaps (const line_table_case &case_)
ASSERT_EQ (7, map->m_column_and_range_bits - map->m_range_bits);
}
/* Example of a line that will eventually be seen to be longer
than LINE_MAP_MAX_COLUMN_NUMBER; the initially seen width is
below that. */
linemap_line_start (line_table, 5, 2000);
location_t loc_start_of_very_long_line
= linemap_position_for_column (line_table, 2000);
location_t loc_too_wide
= linemap_position_for_column (line_table, 4097);
location_t loc_too_wide_2
= linemap_position_for_column (line_table, 4098);
/* ...and back to a sane line length. */
linemap_line_start (line_table, 6, 100);
location_t loc_sane_again = linemap_position_for_column (line_table, 10);
linemap_add (line_table, LC_LEAVE, false, NULL, 0);
/* Multiple files. */
@ -1714,6 +1730,16 @@ test_accessing_ordinary_linemaps (const line_table_case &case_)
assert_loceq ("foo.c", 2, 17, loc_d);
assert_loceq ("foo.c", 3, 700, loc_e);
assert_loceq ("foo.c", 4, 100, loc_back_to_short);
/* In the very wide line, the initial location should be fully tracked. */
assert_loceq ("foo.c", 5, 2000, loc_start_of_very_long_line);
/* ...but once we exceed LINE_MAP_MAX_COLUMN_NUMBER column-tracking should
be disabled. */
assert_loceq ("foo.c", 5, 0, loc_too_wide);
assert_loceq ("foo.c", 5, 0, loc_too_wide_2);
/*...and column-tracking should be re-enabled for subsequent lines. */
assert_loceq ("foo.c", 6, 10, loc_sane_again);
assert_loceq ("bar.c", 1, 150, loc_f);
ASSERT_FALSE (is_location_from_builtin_token (loc_a));

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-01-10 David Malcolm <dmalcolm@redhat.com>
PR c++/77949
* g++.dg/diagnostic/pr77949.C: New test case.
2017-01-10 Martin Sebor <msebor@redhat.com>
PR tree-optimization/78775

7
gcc/testsuite/g++.dg/diagnostic/pr77949.C Normal file
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@ -0,0 +1,7 @@
// Ensure that no fix-it hints are emitted
// { dg-options "-fdiagnostics-parseable-fixits" }
/* Very long line, where a missing semicolon would be suggested for
insertion at column 4097. */
class test { }
// { dg-error "0: expected .;. after class definition" "" { target *-*-* } .-1 }

10
libcpp/ChangeLog
View File

@ -1,3 +1,13 @@
2017-01-10 David Malcolm <dmalcolm@redhat.com>
PR c++/77949
* line-map.c (linemap_position_for_column): When calling
linemap_start_line, detect if a new linemap was created with
0 column bits, and bail out early if this is the case.
(linemap_position_for_loc_and_offset): Replace overzealous
linemap_assert_fails with a simple conditional; use correct
bit count.
2017-01-07 David Malcolm <dmalcolm@redhat.com>
PR c++/72803

19
libcpp/line-map.c
View File

@ -816,8 +816,22 @@ linemap_position_for_column (struct line_maps *set, unsigned int to_column)
}
else
{
/* Otherwise, attempt to start a new line that can hold TO_COLUMN,
with some space to spare. This may or may not lead to a new
linemap being created. */
line_map_ordinary *map = LINEMAPS_LAST_ORDINARY_MAP (set);
r = linemap_line_start (set, SOURCE_LINE (map, r), to_column + 50);
map = LINEMAPS_LAST_ORDINARY_MAP (set);
if (map->m_column_and_range_bits == 0)
{
/* ...then the linemap has column-tracking disabled,
presumably due to exceeding either
LINE_MAP_MAX_LOCATION_WITH_COLS (overall) or
LINE_MAP_MAX_COLUMN_NUMBER (within this line).
Return the start of the linemap, which encodes column 0, for
the whole line. */
return r;
}
}
}
line_map_ordinary *map = LINEMAPS_LAST_ORDINARY_MAP (set);
@ -905,7 +919,10 @@ linemap_position_for_loc_and_offset (struct line_maps *set,
}
column += column_offset;
if (linemap_assert_fails (column < (1u << map->m_column_and_range_bits)))
/* Bail out if the column is not representable within the existing
linemap. */
if (column >= (1u << (map->m_column_and_range_bits - map->m_range_bits)))
return loc;
source_location r =