[PATCH] Fix gdb build on 32-bit hosts w/ --enable-64-bit-bfd

[Pedro Alves]

Building for x86_64/-m32 with --enable-64-bit-bfd, compilation fails
with:

src/gdb/dwarf2read.c: In instantiation of ‘gdb::array_view<const unsigned char> get_gdb_index_contents_from_section(objfile*, T*) [with T = dwarf2_per_objfile]’:
src/gdb/dwarf2read.c:6266:54: required from here
src/gdb/dwarf2read.c:6192:37: error: narrowing conversion of ‘section->dwarf2_section_info::size’ from ‘bfd_size_type {aka long long unsigned int}’ to ‘size_t {aka unsigned int}’ inside { } [-Werror=narrowing]
return {section->buffer, section->size};
~~~~~~~~~^~~~

This fixes it.

gdb/ChangeLog:
2018-12-04 Pedro Alves <***@redhat.com>

* dwarf2read.c (get_gdb_index_contents_from_section): Use
gdb::make_array_view.
---
gdb/dwarf2read.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 8bfbd693940..30bc101f11c 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -6189,7 +6189,13 @@ get_gdb_index_contents_from_section (objfile *obj, T *section_owner)

dwarf2_read_section (obj, section);

- return {section->buffer, section->size};
+ /* dwarf2_section_info::size is a bfd_size_type, while
+ gdb::array_view works with size_t. On 32-bit hosts, with
+ --enable-64-bit-bfd, bfd_size_type is a 64-bit type, while size_t
+ is 32-bit. So we need an explicit narrowing conversion here.
+ This is fine, because it's impossible to allocate or mmap an
+ array/buffer larger than what size_t can represent. */
+ return gdb::make_array_view (section->buffer, section->size);
}

/* Lookup the index cache for the contents of the index associated to

[Simon Marchi]

Post by Pedro Alves
Building for x86_64/-m32 with --enable-64-bit-bfd, compilation fails
src/gdb/dwarf2read.c:6266:54: required from here
src/gdb/dwarf2read.c:6192:37: error: narrowing conversion of ‘section->dwarf2_section_info::size’ from ‘bfd_size_type {aka long long unsigned int}’ to ‘size_t {aka unsigned int}’ inside { } [-Werror=narrowing]
return {section->buffer, section->size};
~~~~~~~~~^~~~
This fixes it.

[Pedro Alves]

Post by Pedro Alves
Building for x86_64/-m32 with --enable-64-bit-bfd, compilation fails
src/gdb/dwarf2read.c:6266:54: required from here
src/gdb/dwarf2read.c:6192:37: error: narrowing conversion of ‘section->dwarf2_section_info::size’ from ‘bfd_size_type {aka long long unsigned int}’ to ‘size_t {aka unsigned int}’ inside { } [-Werror=narrowing]
return {section->buffer, section->size};
~~~~~~~~~^~~~
This fixes it.

Woops, thanks, LGTM.

Pushed, thanks.

Thanks,
Pedro Alves