Hi Nathan,

On 2022-11-08 00:03, Nathan Sidwell wrote:
On 11/3/22 11:06, Torbjorn SVENSSON wrote:


On 2022-11-03 15:17, Nathan Sidwell wrote:
On 10/28/22 05:15, Torbjörn SVENSSON wrote:
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.

include/ChangeLog:

    * filenames.h: Added IS_REAL_ABSOLUTE_PATH macro to check if
    path is absolute and not semi-absolute on Windows.

Hm, this is unfortunate.  The current IS_ABSOLUTE_PATH, is really 'not relative to cwd', and even then that's untrue if the drive letter there is the drive letter of cwd, right?

It's awkward to have a new macro for just this purpose and the new name isn't very indicative of the difference to the current IS_ABSOLUTE_PATH.

Would it be better to not deal with drive letters here?  How prevalent are they these days in windows?  Would something like

    if (IS_DIR_SEPARATOR (ptr[ptr[0] == '.'])

suffice?

I don't think you can ignore the drive letter part... see below.


#include <stdio.h>
#include "include/filenames.h"
#define TF(x) ((x) ? "true" : "false")
int main(int argc, char *argv[]) {
   const char *test[] = {
       /* absolute */      "c:\\foo", "c:/foo", "/foo", "\\foo",
       /* semi-absolute */ "c:foo",
       /* relative */      "foo", "./foo", ".\\foo",
   };
   for (int i = 0; i < sizeof(test) / sizeof(test[0]); i++) {
     const char *ptr = test[i];
     printf("\nptr: %s\n", ptr);
     printf("  IS_DOS_ABSOLUTE_PATH: %s\n",
            TF(IS_DOS_ABSOLUTE_PATH(ptr)));
     printf("  IS_DOS_REAL_ABSOLUTE_PATH: %s\n",
            TF(IS_DOS_REAL_ABSOLUTE_PATH(ptr)));
     printf("  IS_DIR_SEPARATOR: %s\n",
            TF(IS_DIR_SEPARATOR(ptr[ptr[0] == '.'])));
   }
   return 0;
}


The output is:

ptr: c:\foo
   IS_DOS_ABSOLUTE_PATH: true
   IS_DOS_REAL_ABSOLUTE_PATH: true
   IS_DIR_SEPARATOR: false

ptr: c:/foo
   IS_DOS_ABSOLUTE_PATH: true
   IS_DOS_REAL_ABSOLUTE_PATH: true
   IS_DIR_SEPARATOR: false

ptr: /foo
   IS_DOS_ABSOLUTE_PATH: true
   IS_DOS_REAL_ABSOLUTE_PATH: true
   IS_DIR_SEPARATOR: true

ptr: \foo
   IS_DOS_ABSOLUTE_PATH: true
   IS_DOS_REAL_ABSOLUTE_PATH: true
   IS_DIR_SEPARATOR: false

ptr: c:foo
   IS_DOS_ABSOLUTE_PATH: true
   IS_DOS_REAL_ABSOLUTE_PATH: false
   IS_DIR_SEPARATOR: false

ptr: foo
   IS_DOS_ABSOLUTE_PATH: false
   IS_DOS_REAL_ABSOLUTE_PATH: false
   IS_DIR_SEPARATOR: false

ptr: ./foo
   IS_DOS_ABSOLUTE_PATH: false
   IS_DOS_REAL_ABSOLUTE_PATH: false
   IS_DIR_SEPARATOR: true

ptr: .\foo
   IS_DOS_ABSOLUTE_PATH: false
   IS_DOS_REAL_ABSOLUTE_PATH: false
   IS_DIR_SEPARATOR: false



or, failing that perhaps put some explicit WINDOWS-specific #ifdef'd code there?  It's a real corner case.

Would you rather have something like this in module.cc?

if (ptr[0] == '.')
   {
     if IS_DIR_SEPARATOR (ptr[1]))
       return get_module (build_string (strlen (ptr), ptr));
   }
else
   {
#if HAVE_DOS_BASED_FILE_SYSTEM
     if (HAS_DRIVE_SPEC (ptr) && IS_DIR_SEPARATOR (ptr[2]))
#else
     if (IS_ABSOLUTE_PATH (ptr))
#endif
       return get_module (build_string (strlen (ptr), ptr));
   }

Yes, something like the above, but I think you're missing "/bob' in the DOS_BASED case?  shouldn't that also be a pathname?

if (IS_DIR_SEPARATOR (ptr[ptr[0] == '.']) // ./FOO or /FOO
#if HAVE_DOS_BASED_FILE_SYSTEM
    // DOS-FS IS_ABSOLUTE_PATH thinks 'A:B' is absolute, but we need to consider
     // that as a module:partition.
     || (HAS_DRIVE_SPEC (ptr) && IS_DIR_SEPARATOR (ptr[2])) // A:/FOO
#endif
     || false)
    return ....

Does (something like) that work?

I tested it and your solution appears to work.
Are you okay with me pushing that solution or do you want me to send a v2 with it first?

Kind regards,
Torbjörn


nathan



Let me know what you prefer.

Kind regards,
Torbjörn


nathan


gcc/cp/ChangeLog:

    * module.cc: Use IS_REAL_ABSOLUTE_PATH macro.

Co-Authored-By: Yvan ROUX <yvan.r...@foss.st.com>
Signed-off-by: Torbjörn SVENSSON <torbjorn.svens...@foss.st.com>
---
  gcc/cp/module.cc    | 2 +-
  include/filenames.h | 4 ++++
  2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 9957df510e6..84680e183b7 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -13958,7 +13958,7 @@ 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)) +  if (ptr[0] == '.' ? IS_DIR_SEPARATOR (ptr[1]) : IS_REAL_ABSOLUTE_PATH (ptr))
      /* A header name.  */
      return get_module (build_string (strlen (ptr), ptr));
diff --git a/include/filenames.h b/include/filenames.h
index 6c72c422edd..d04fccfed64 100644
--- a/include/filenames.h
+++ b/include/filenames.h
@@ -43,6 +43,7 @@ extern "C" {
  #  define HAS_DRIVE_SPEC(f) HAS_DOS_DRIVE_SPEC (f)
  #  define IS_DIR_SEPARATOR(c) IS_DOS_DIR_SEPARATOR (c)
  #  define IS_ABSOLUTE_PATH(f) IS_DOS_ABSOLUTE_PATH (f)
+#  define IS_REAL_ABSOLUTE_PATH(f) IS_DOS_REAL_ABSOLUTE_PATH (f)
  #else /* not DOSish */
  #  if defined(__APPLE__)
  #    ifndef HAVE_CASE_INSENSITIVE_FILE_SYSTEM
@@ -52,6 +53,7 @@ extern "C" {
  #  define HAS_DRIVE_SPEC(f) (0)
  #  define IS_DIR_SEPARATOR(c) IS_UNIX_DIR_SEPARATOR (c)
  #  define IS_ABSOLUTE_PATH(f) IS_UNIX_ABSOLUTE_PATH (f)
+#  define IS_REAL_ABSOLUTE_PATH(f) IS_ABSOLUTE_PATH (f)
  #endif
  #define IS_DIR_SEPARATOR_1(dos_based, c)                \
@@ -67,6 +69,8 @@ extern "C" {
  #define IS_DOS_DIR_SEPARATOR(c) IS_DIR_SEPARATOR_1 (1, c)
  #define IS_DOS_ABSOLUTE_PATH(f) IS_ABSOLUTE_PATH_1 (1, f)
+#define IS_DOS_REAL_ABSOLUTE_PATH(f) \
+  ((f)[0] && (f)[1] == ':' && ((f)[2] == '/' || (f)[2] == '\\'))
  #define HAS_DOS_DRIVE_SPEC(f) HAS_DRIVE_SPEC_1 (1, f)
  #define IS_UNIX_DIR_SEPARATOR(c) IS_DIR_SEPARATOR_1 (0, c)


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