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
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David Malcolm
David Malcolm
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2017-01-10 David Malcolm <dmalcolm@redhat.com>
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PR c++/77949
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* input.c (selftest::test_accessing_ordinary_linemaps): Verify
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that we correctly handle column numbers greater than
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LINE_MAP_MAX_COLUMN_NUMBER.
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2017-01-10 Martin Sebor <msebor@redhat.com>
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PR tree-optimization/78775
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@ -1,3 +1,10 @@
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2017-01-10 David Malcolm <dmalcolm@redhat.com>
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PR c++/77949
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* parser.c (cp_parser_class_specifier_1): Only suggest inserting
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a missing semicolon if we have a valid insertion location for
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the fix-it hint.
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2017-01-10 Jason Merrill <jason@redhat.com>
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FI 20, decomposition declaration with parenthesized initializer.
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@ -22164,7 +22164,10 @@ cp_parser_class_specifier_1 (cp_parser* parser)
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next_loc = linemap_position_for_loc_and_offset (line_table, loc, 1);
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rich_location richloc (line_table, next_loc);
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richloc.add_fixit_insert_before (next_loc, ";");
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/* If we successfully offset the location, suggest the fix-it. */
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if (next_loc != loc)
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richloc.add_fixit_insert_before (next_loc, ";");
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if (CLASSTYPE_DECLARED_CLASS (type))
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error_at_rich_loc (&richloc,
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26
gcc/input.c
26
gcc/input.c
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@ -1699,6 +1699,22 @@ test_accessing_ordinary_linemaps (const line_table_case &case_)
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ASSERT_EQ (7, map->m_column_and_range_bits - map->m_range_bits);
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}
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/* Example of a line that will eventually be seen to be longer
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than LINE_MAP_MAX_COLUMN_NUMBER; the initially seen width is
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below that. */
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linemap_line_start (line_table, 5, 2000);
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location_t loc_start_of_very_long_line
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= linemap_position_for_column (line_table, 2000);
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location_t loc_too_wide
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= linemap_position_for_column (line_table, 4097);
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location_t loc_too_wide_2
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= linemap_position_for_column (line_table, 4098);
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/* ...and back to a sane line length. */
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linemap_line_start (line_table, 6, 100);
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location_t loc_sane_again = linemap_position_for_column (line_table, 10);
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linemap_add (line_table, LC_LEAVE, false, NULL, 0);
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/* Multiple files. */
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@ -1714,6 +1730,16 @@ test_accessing_ordinary_linemaps (const line_table_case &case_)
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assert_loceq ("foo.c", 2, 17, loc_d);
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assert_loceq ("foo.c", 3, 700, loc_e);
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assert_loceq ("foo.c", 4, 100, loc_back_to_short);
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/* In the very wide line, the initial location should be fully tracked. */
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assert_loceq ("foo.c", 5, 2000, loc_start_of_very_long_line);
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/* ...but once we exceed LINE_MAP_MAX_COLUMN_NUMBER column-tracking should
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be disabled. */
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assert_loceq ("foo.c", 5, 0, loc_too_wide);
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assert_loceq ("foo.c", 5, 0, loc_too_wide_2);
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/*...and column-tracking should be re-enabled for subsequent lines. */
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assert_loceq ("foo.c", 6, 10, loc_sane_again);
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assert_loceq ("bar.c", 1, 150, loc_f);
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ASSERT_FALSE (is_location_from_builtin_token (loc_a));
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@ -1,3 +1,8 @@
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2017-01-10 David Malcolm <dmalcolm@redhat.com>
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PR c++/77949
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* g++.dg/diagnostic/pr77949.C: New test case.
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2017-01-10 Martin Sebor <msebor@redhat.com>
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PR tree-optimization/78775
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@ -0,0 +1,7 @@
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// Ensure that no fix-it hints are emitted
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// { dg-options "-fdiagnostics-parseable-fixits" }
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/* Very long line, where a missing semicolon would be suggested for
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insertion at column 4097. */
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class test { }
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// { dg-error "0: expected .;. after class definition" "" { target *-*-* } .-1 }
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@ -1,3 +1,13 @@
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2017-01-10 David Malcolm <dmalcolm@redhat.com>
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PR c++/77949
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* line-map.c (linemap_position_for_column): When calling
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linemap_start_line, detect if a new linemap was created with
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0 column bits, and bail out early if this is the case.
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(linemap_position_for_loc_and_offset): Replace overzealous
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linemap_assert_fails with a simple conditional; use correct
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bit count.
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2017-01-07 David Malcolm <dmalcolm@redhat.com>
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PR c++/72803
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@ -816,8 +816,22 @@ linemap_position_for_column (struct line_maps *set, unsigned int to_column)
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}
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else
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{
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/* Otherwise, attempt to start a new line that can hold TO_COLUMN,
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with some space to spare. This may or may not lead to a new
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linemap being created. */
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line_map_ordinary *map = LINEMAPS_LAST_ORDINARY_MAP (set);
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r = linemap_line_start (set, SOURCE_LINE (map, r), to_column + 50);
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map = LINEMAPS_LAST_ORDINARY_MAP (set);
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if (map->m_column_and_range_bits == 0)
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{
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/* ...then the linemap has column-tracking disabled,
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presumably due to exceeding either
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LINE_MAP_MAX_LOCATION_WITH_COLS (overall) or
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LINE_MAP_MAX_COLUMN_NUMBER (within this line).
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Return the start of the linemap, which encodes column 0, for
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the whole line. */
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return r;
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}
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}
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}
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line_map_ordinary *map = LINEMAPS_LAST_ORDINARY_MAP (set);
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@ -905,7 +919,10 @@ linemap_position_for_loc_and_offset (struct line_maps *set,
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}
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column += column_offset;
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if (linemap_assert_fails (column < (1u << map->m_column_and_range_bits)))
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/* Bail out if the column is not representable within the existing
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linemap. */
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if (column >= (1u << (map->m_column_and_range_bits - map->m_range_bits)))
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return loc;
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source_location r =
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