Re: PING [PATCH v3] c++: Allow module name to be a single letter on Windows

[Nathan Sidwell <nathan@acm.org>]

On 11/25/22 14:03, Torbjorn SVENSSON wrote:
> Hi,
> 
> Ping, https://gcc.gnu.org/pipermail/gcc-patches/2022-November/606528.html

ok, thanks!

> 
> Kind regards,
> Torbjörn
> 
> On 2022-11-17 14:20, Torbjörn SVENSSON wrote:
>> v1 -> v2:
>> Paths without "C:" part can still be absolute if they start with / or
>> \ on Windows.
>>
>> v2 -> v3:
>> Use alternative approach by having platform specific code in module.cc.
>>
>> Truth table for the new expression:
>> c:\foo     -> true
>> c:/foo     -> true
>> /foo       -> true
>> \foo       -> true
>> c:foo      -> false
>> foo        -> false
>> ./foo      -> true
>> .\foo      -> true
>>
>>
>> Ok for trunk?
>>
>> ---
>>
>> On Windows, the ':' character is special and when the module name is
>> a single character, like 'A', then the flatname would be (for
>> example) 'A:Foo'. On Windows, 'A:Foo' is treated as an absolute
>> path by the module loader and is likely not found.
>>
>> Without this patch, the test case pr98944_c.C fails with:
>>
>> In module imported at /src/gcc/testsuite/g++.dg/modules/pr98944_b.C:7:1,
>> of module A:Foo, imported at /src/gcc/testsuite/g++.dg/modules/pr98944_c.C:7:
>> A:Internals: error: header module expected, module 'A:Internals' found
>> A:Internals: error: failed to read compiled module: Bad file data
>> A:Internals: note: compiled module file is 'gcm.cache/A-Internals.gcm'
>> In module imported at /src/gcc/testsuite/g++.dg/modules/pr98944_c.C:7:8:
>> A:Foo: error: failed to read compiled module: Bad import dependency
>> A:Foo: note: compiled module file is 'gcm.cache/A-Foo.gcm'
>> A:Foo: fatal error: returning to the gate for a mechanical issue
>> compilation terminated.
>>
>> gcc/cp/ChangeLog:
>>
>>     * module.cc: On Windows, 'A:Foo' is supposed to be a module
>>     and not a path.
>>
>> Tested on Windows with arm-none-eabi for Cortex-M3 in gcc-11 tree.
>>
>> Co-Authored-By: Yvan ROUX <yvan.roux@foss.st.com>
>> Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
>> ---
>>   gcc/cp/module.cc | 10 +++++++++-
>>   1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
>> index 0e9af318ba4..fa41a86213f 100644
>> --- a/gcc/cp/module.cc
>> +++ b/gcc/cp/module.cc
>> @@ -13960,7 +13960,15 @@ get_module (tree name, module_state *parent, bool 
>> partition)
>>   static module_state *
>>   get_module (const char *ptr)
>>   {
>> -  if (ptr[0] == '.' ? IS_DIR_SEPARATOR (ptr[1]) : IS_ABSOLUTE_PATH (ptr))
>> +  /* On DOS based file systems, there is an ambiguity with A:B which can be
>> +     interpreted as a module Module:Partition or Drive:PATH.  Interpret strings
>> +     which clearly starts as pathnames as header-names and everything else is
>> +     treated as a (possibly malformed) named moduled.  */
>> +  if (IS_DIR_SEPARATOR (ptr[ptr[0] == '.']) // ./FOO or /FOO
>> +#if HAVE_DOS_BASED_FILE_SYSTEM
>> +      || (HAS_DRIVE_SPEC (ptr) && IS_DIR_SEPARATOR (ptr[2])) // A:/FOO
>> +#endif
>> +      || false)
>>       /* A header name.  */
>>       return get_module (build_string (strlen (ptr), ptr));

-- 
Nathan Sidwell