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The find-upper-bound-for-completion algorithm in the name components accelerator table in dwarf2read.c increments a char in a string, and asserts that it's not incrementing a 0xff char, but that's incorrect. First, we shouldn't be calling gdb_assert on input. Then, if "char" is signed, comparing a caracther with "0xff" will never yield true, which is caught by Clang with: error: comparison of constant 255 with expression of type '....' (aka 'char') is always true [-Werror,-Wtautological-constant-out-of-range-compare] gdb_assert (after.back () != 0xff); ~~~~~~~~~~~~~ ^ ~~~~ And then, 0xff is a valid character on non-UTF-8/ASCII character sets. E.g., it's 'ÿ' in Latin1. While GCC nor Clang support !ASCII && !UTF-8 characters in identifiers (GCC supports UTF-8 characters only via UCNs, see https://gcc.gnu.org/onlinedocs/cpp/Character-sets.html), but other compilers might (Visual Studio?), so it doesn't hurt to handle it correctly. Testing is covered by extending the dw2_expand_symtabs_matching unit tests with relevant cases. However, without further changes, the unit tests still fail... The problem is that cp-name-parser.y assumes that identifiers are ASCII (via ISALPHA/ISALNUM). This commit fixes that too, so that we can unit test the dwarf2read.c changes. (The regular C/C++ lexer in c-lang.y needs a similar treatment, but I'm leaving that for another patch.) While doing this, I noticed a thinko in the computation of the upper bound for completion in dw2_expand_symtabs_matching_symbol. We're using std::upper_bound but we should use std::lower_bound. I extended the unit test with a case that I thought would expose it, this one: + /* These are used to check that the increment-last-char in the + matching algorithm for completion doesn't match "t1_fund" when + completing "t1_func". */ + "t1_func", + "t1_func1", + "t1_fund", + "t1_fund1", The algorithm actually returns "t1_fund1" as lower bound, so "t1_fund" matches incorrectly. But turns out the problem is masked because later here: for (;lower != upper; ++lower) { const char *qualified = index.symbol_name_at (lower->idx); if (!lookup_name_matcher.matches (qualified) the lookup_name_matcher.matches check above filters out "t1_fund" because that doesn't start with "t1_func". I'll fix the latent bug in follow up patches, after factoring things out a bit in a way that allows unit testing the relevant code more directly. gdb/ChangeLog: 2017-11-21 Pedro Alves <palves@redhat.com> * cp-name-parser.y (cp_ident_is_alpha, cp_ident_is_alnum): New. (symbol_end): Use cp_ident_is_alnum. (yylex): Use cp_ident_is_alpha and cp_ident_is_alnum. * dwarf2read.c (make_sort_after_prefix_name): New function. (dw2_expand_symtabs_matching_symbol): Use it. (test_symbols): Add more symbols. (run_test): Add tests.
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