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[Bug gdb/22670] regressions in Ada caused by introduction of wild matching in C++ patch series


https://sourceware.org/bugzilla/show_bug.cgi?id=22670

--- Comment #18 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Joel Brobecker <brobecke@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=59cc4834e53565da1de4a7b615ed8890ed55c7da

commit 59cc4834e53565da1de4a7b615ed8890ed55c7da
Author: Joel Brobecker <brobecker@adacore.com>
Date:   Tue Mar 27 08:57:16 2018 -0500

    problem looking up some symbols when they have a linkage name

    This patch fixes a known failure in gdb.ada/maint_with_ada.exp
    (maintenance check-psymtabs). Another way to witness the same
    issue is by considering the following Ada declarations...

       type Wrapper is record
          A : Integer;
       end record;
       u00045 : constant Wrapper := (A => 16#060287af#);
       pragma Export (C, u00045, "symada__cS");

    ... which declares a variable name "u00045" but with a linkage
    name which is "symada__cS". This variable is a record with one
    component, the Ada equivalent of a struct with one field in C.
    Trying to print that variable's value currently yields:

        (gdb) p /x <symada__cS>
        'symada(char, signed)' has unknown type; cast it to its declared type

    This indicates that GDB was only able to find the minimal symbol,
    but not the full symbol. The expected output is:

        (gdb) print /x <symada__cS>
        $1 = (a => 0x60287af)

    The error message gives a hint about what's happening: We processed
    the symbol through gdb_demangle, which in the case of this particular
    symbol name, ends up matching the C++ naming scheme. As a result,
    the demangler transforms our symbol name into 'symada(char, signed)',
    thus breaking Ada lookups.

    This patch fixes the issue by first introducing a new language_defn
    attribute called la_store_sym_names_in_linkage_form_p, which is a boolean
    to be set to true for the few languages that do not want their symbols
    to have their names stored in demangled form, and false otherwise.
    We then use this language attribute to skip the call to gdb_demangle
    for all languages whose la_store_sym_names_in_linkage_form_p is true.

    In terms of the selection of languages for which the new attribute
    is set to true, the selection errs on the side of preserving the
    existing behavior, and only changes the behavior for the languages
    where we are certain storing symbol names in demangling form is not
    needed. It is conceivable that other languages might be in the same
    situation, but I not knowing in detail the symbol name enconding
    strategy, I decided to play it safe and let other language maintainers
    potentially adjust their language if it makes sense to do so.

    gdb/ChangeLog:

            PR gdb/22670
            * dwarf2read.c (dwarf2_physname): Do not return the demangled
            symbol name if the CU's language stores symbol names in linkage
            format.
            * language.h (struct language_defn)
            <la_store_sym_names_in_linkage_form_p>: New field.  Adjust
            all instances of this struct.

    gdb/testsuite/ChangeLog:

            * gdb.ada/maint_with_ada.exp: Remove PR gdb/22670 setup_kfail.

            * gdb.ada/notcplusplus: New testcase.

            * gdb.base/c-linkage-name.c: New file.
            * gdb.base/c-linkage-name.exp: New testcase.

    Tested on x86_64-linux.
    This also passes AdaCore's internal GDB testsuite.

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