Lewis Hyatt via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> Hello-
>
> This fixes an old PR, bootstrap + regtest on x86-64 Linux. Please let me know
> if it's ok? Thanks!
>
> -Lewis
>
> -- >8 --
>
> As noted in the PR, GCC will segfault if a file name is first seen in a
> linemarker directive, and then later seen in a normal #include. This is
> because the fake include process adds the file to the cache with a null PATH
> member. The normal #include finds this file in the cache and then attempts
> to use the null PATH. Resolve by adding the file to the cache with a unique
> starting directory, so that the fake entry will only be found by a
> subsequent fake include, not by a real one.
>
> libcpp/ChangeLog:
>
> PR preprocessor/61474
> * files.cc (_cpp_find_file): Set DONT_READ to TRUE for fake
> include files.
> (_cpp_fake_include): Pass a unique cpp_dir* address so
> the fake file will not be found when looked up for real.
>
> gcc/testsuite/ChangeLog:
>
> PR preprocessor/61474
> * c-c++-common/cpp/pr61474-2.h: New test.
> * c-c++-common/cpp/pr61474.c: New test.
> * c-c++-common/cpp/pr61474.h: New test.
Neat fix! I don't know this code very well, but I agree it looks
correct. OK if no-one objects in 24 hours.
Thanks,
Richard
> ---
> libcpp/files.cc | 11 +++++++++--
> gcc/testsuite/c-c++-common/cpp/pr61474-2.h | 1 +
> gcc/testsuite/c-c++-common/cpp/pr61474.c | 5 +++++
> gcc/testsuite/c-c++-common/cpp/pr61474.h | 6 ++++++
> 4 files changed, 21 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/c-c++-common/cpp/pr61474-2.h
> create mode 100644 gcc/testsuite/c-c++-common/cpp/pr61474.c
> create mode 100644 gcc/testsuite/c-c++-common/cpp/pr61474.h
>
> diff --git a/libcpp/files.cc b/libcpp/files.cc
> index 43a8894b7de..27301d79fa4 100644
> --- a/libcpp/files.cc
> +++ b/libcpp/files.cc
> @@ -541,7 +541,9 @@ _cpp_find_file (cpp_reader *pfile, const char *fname,
> cpp_dir *start_dir,
> = (kind == _cpp_FFK_PRE_INCLUDE
> || (pfile->buffer && pfile->buffer->file->implicit_preinclude));
>
> - if (kind != _cpp_FFK_FAKE)
> + if (kind == _cpp_FFK_FAKE)
> + file->dont_read = true;
> + else
> /* Try each path in the include chain. */
> for (;;)
> {
> @@ -1490,7 +1492,12 @@ cpp_clear_file_cache (cpp_reader *pfile)
> void
> _cpp_fake_include (cpp_reader *pfile, const char *fname)
> {
> - _cpp_find_file (pfile, fname, pfile->buffer->file->dir, 0, _cpp_FFK_FAKE,
> 0);
> + /* It does not matter what are the contents of fake_source_dir, it will
> never
> + be inspected; we just use its address to uniquely signify that this file
> + was added as a fake include, so a later call to _cpp_find_file (to
> include
> + the file for real) won't find the fake one in the hash table. */
> + static cpp_dir fake_source_dir;
> + _cpp_find_file (pfile, fname, &fake_source_dir, 0, _cpp_FFK_FAKE, 0);
> }
>
> /* Not everyone who wants to set system-header-ness on a buffer can
> diff --git a/gcc/testsuite/c-c++-common/cpp/pr61474-2.h
> b/gcc/testsuite/c-c++-common/cpp/pr61474-2.h
> new file mode 100644
> index 00000000000..6f70f09beec
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/cpp/pr61474-2.h
> @@ -0,0 +1 @@
> +#pragma once
> diff --git a/gcc/testsuite/c-c++-common/cpp/pr61474.c
> b/gcc/testsuite/c-c++-common/cpp/pr61474.c
> new file mode 100644
> index 00000000000..f835a40fc7a
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/cpp/pr61474.c
> @@ -0,0 +1,5 @@
> +/* { dg-do preprocess } */
> +#include "pr61474.h"
> +/* Make sure that the file can be included for real, after it was
> + fake-included by the linemarker directives in pr61474.h. */
> +#include "pr61474-2.h"
> diff --git a/gcc/testsuite/c-c++-common/cpp/pr61474.h
> b/gcc/testsuite/c-c++-common/cpp/pr61474.h
> new file mode 100644
> index 00000000000..d9e8c3a1fec
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/cpp/pr61474.h
> @@ -0,0 +1,6 @@
> +/* Create a fake include for pr61474-2.h and exercise looking it up. */
> +/* Use #pragma once to check also that the fake-include entry in the file
> + cache does not cause a problem in libcpp/files.cc:has_unique_contents().
> */
> +#pragma once
> +# 1 "pr61474-2.h" 1
> +# 2 "pr61474-2.h" 1
