https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80646
Bug ID: 80646
Summary: [Regression] wrong type info for extern inline
function when compiling Emacs
Product: gcc
Version: 6.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: eggert at gnu dot org
Target Milestone: ---
Created attachment 41327
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41327&action=edit
gzipped tarball of three source files illustrating the bug
GCC 6.3.1 x86-64 20161221 (Red Hat 6.3.1-1) outputs incorrect debug information
for inline functions in some cases, and this can make programs hard to debug.
The problem does not occur for GCC 4.8.5 20150623 (Red Hat 4.8.5-11), so this
appears to be a regression.
I ran into the problem while attempting to debug GNU Emacs, and constructed a
small test case to illustrate it. To reproduce it on Fedora 25 x86-64 with
6.3.1 20161221, extract the files lisp.h, t.c and u.c from the attached
tarball, and compile them by running the shell command:
gcc -g3 -O2 t.c u.c
Then use GDB as follows:
$ gdb a.out
...
(gdb) ptype make_number
type = int ()
(gdb) ptype make_natnum
type = struct {
long i;
} (long)
(gdb) ptype XIL
type = struct {
long i;
} (long)
(gdb)
The reported type of 'make_number' is incorrect: it should be the same type as
that of make_natnum and XIL, but instead is a function returning 'int'. This
incorrect type can cause GDB to print incorrect results in expressions
involving make_number. Looking at the assembly-language output, it appears that
GCC is generating the wrong debug information for this example.
