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authorDavid Malcolm <dmalcolm@redhat.com>2017-01-10 21:54:09 +0000
committerDavid Malcolm <dmalcolm@gcc.gnu.org>2017-01-10 21:54:09 +0000
commitb9f4757f8eb94d4b145613ee5047f3f95452f9d2 (patch)
tree4f329935d56c10c19a73497a7006a9a709292f4f /gcc/input.c
parent6fcb740ac456e4703b337584b26305a77a5c5038 (diff)
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Fix issues with unrepresentable column numbers (PR c++/77949)
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
Diffstat (limited to 'gcc/input.c')
-rw-r--r--gcc/input.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/gcc/input.c b/gcc/input.c
index bbb6abb..3e67314 100644
--- a/gcc/input.c
+++ b/gcc/input.c
@@ -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));