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.
Successfully bootstrapped®rtested on x86_64-pc-linux-gnu.
Committed to trunk as r244292.
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.
---
gcc/cp/parser.c | 5 ++++-
gcc/input.c | 26 ++++++++++++++++++++++++++
gcc/testsuite/g++.dg/diagnostic/pr77949.C | 7 +++++++
libcpp/line-map.c | 19 ++++++++++++++++++-
4 files changed, 55 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/diagnostic/pr77949.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index b94270d..6b250db 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -22120,7 +22120,10 @@ 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,
diff --git a/gcc/input.c b/gcc/input.c
index 4df47f2..6e45538 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));
diff --git a/gcc/testsuite/g++.dg/diagnostic/pr77949.C
b/gcc/testsuite/g++.dg/diagnostic/pr77949.C
new file mode 100644
index 0000000..0d8b333
--- /dev/null
+++ b/gcc/testsuite/g++.dg/diagnostic/pr77949.C
@@ -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
}
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index b410c00..949489e 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -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 =
--
1.8.5.3
