Consider compiling test.c, with this content:
VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV
#include "test.h"
int
main (int argc, char **argv)
{
int a = PLUS (1,2);
int b = PLUS (3,4);
return 0;
}
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...where test.h has this content:
VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV
extern int foo ();
#define PLUS(A, B) A + B
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The undocumented -fdump-internal-locations option outputs this information
to stderr, showing what each location_t value means. Source code
lines are quoted, showing both per-line location_t values and
per-line&column location_t values (written vertically under the
corresponding character of source code).
VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV
RESERVED LOCATIONS
location_t interval: 0 <= loc < 2
ORDINARY MAP: 0
location_t interval: 32 <= loc < 64
file: test.c
starting at line: 1
column and range bits: 12
column bits: 7
range bits: 5
reason: 0 (LC_ENTER)
included from location: 0
test.c: 1|loc: 32|#include "test.h"
|69269258258148147
|46802468024680246
ORDINARY MAP: 1
location_t interval: 64 <= loc < 96
file: <built-in>
starting at line: 0
column and range bits: 0
column bits: 0
range bits: 0
reason: 2 (LC_RENAME)
included from location: 0
ORDINARY MAP: 2
location_t interval: 96 <= loc < 128
file: <command-line>
starting at line: 0
column and range bits: 0
column bits: 0
range bits: 0
reason: 2 (LC_RENAME)
included from location: 0
ORDINARY MAP: 3
location_t interval: 128 <= loc < 250240
file: /usr/include/stdc-predef.h
starting at line: 1
column and range bits: 12
column bits: 7
range bits: 5
reason: 0 (LC_ENTER)
included from location: 127 (in ordinary map 2)
(contents of /usr/include/stdc-predef.h snipped for brevity)
ORDINARY MAP: 4
location_t interval: 250240 <= loc < 250272
file: <command-line>
starting at line: 32
column and range bits: 12
column bits: 7
range bits: 5
reason: 1 (LC_LEAVE)
included from location: 0
ORDINARY MAP: 5
location_t interval: 250272 <= loc < 254368
file: test.c
starting at line: 1
column and range bits: 12
column bits: 7
range bits: 5
reason: 2 (LC_RENAME)
included from location: 0
test.c: 1|loc:250272|#include "test.h"
|00000000000000000
|33344445556667778
|03603692692582581
|46802468024680246
ORDINARY MAP: 6
location_t interval: 254368 <= loc < 266720
file: test.h
starting at line: 1
column and range bits: 12
column bits: 7
range bits: 5
reason: 0 (LC_ENTER)
included from location: 250272 (in ordinary map 5)
test.h: 1|loc:254368|extern int foo ();
|444444444444444444
|444455566677788899
|036926925825814814
|024680246802468024
test.h: 2|loc:258464|
|
|
|
|
test.h: 3|loc:262560|#define PLUS(A, B) A + B
|222222222222233333333333
|566677788899900011122223
|925825814814704703603692
|246802468024680246802468
test.h: 4|loc:266656|
|
|
|
|
ORDINARY MAP: 7
location_t interval: 266720 <= loc < 299520
file: test.c
starting at line: 2
column and range bits: 12
column bits: 7
range bits: 5
reason: 1 (LC_LEAVE)
included from location: 0
test.c: 2|loc:266720|
|
|
|
|
test.c: 3|loc:270816|int
|000
|889
|481
|802
test.c: 4|loc:274912|main (int argc, char **argv)
|4455555555555555555555555555
|9900011122223334445556667778
|4704703603692692582581481470
|4680246802468024680246802468
test.c: 5|loc:279008|{
|9
|0
|4
|0
test.c: 6|loc:283104| int a = PLUS (1,2);
|333333333333333333333
|112222333444555666777
|360369269258258148147
|680246802468024680246
test.c: 7|loc:287200| int b = PLUS (3,4);
|777777777777777777777
|222333444555666777888
|369269258258148147047
|246802468024680246802
test.c: 8|loc:291296| return 0;
|11111111111
|33344455566
|26925825814
|80246802468
test.c: 9|loc:295392|}
|5
|4
|2
|4
test.c: 10|loc:299488|
|
|
|
|
UNALLOCATED LOCATIONS
location_t interval: 299520 <= loc < 2147483632
MACRO 3: PLUS (7 tokens)
location_t interval: 2147483632 <= loc < 2147483639
test.c:7:11: note: expansion point is location 287555
7 | int b = PLUS (3,4);
| ^~~~
map->start_location: 2147483632
macro_locations:
0: 287744, 263200
test.c:7:17: note: token 0 has x-location == 287744
7 | int b = PLUS (3,4);
| ^
test.c:7:17: note: token 0 has y-location == 263200
1: 263264, 263264
In file included from test.c:1:
test.h:3:22: note: token 1 has x-location == y-location == 263264
3 | #define PLUS(A, B) A + B
| ^
2: 287808, 263328
test.c:7:19: note: token 2 has x-location == 287808
7 | int b = PLUS (3,4);
| ^
test.c:7:19: note: token 2 has y-location == 263328
3: 0, 0
cc1: note: token 3 has x-location == y-location == 0
4: 0, 0
cc1: note: token 4 has x-location == y-location == 0
5: 0, 0
cc1: note: token 5 has x-location == y-location == 0
6: 0, 0
cc1: note: token 6 has x-location == y-location == 0
MACRO 2: PLUS (7 tokens)
location_t interval: 2147483639 <= loc < 2147483646
test.c:6:11: note: expansion point is location 283459
6 | int a = PLUS (1,2);
| ^~~~
map->start_location: 2147483639
macro_locations:
0: 283648, 263200
test.c:6:17: note: token 0 has x-location == 283648
6 | int a = PLUS (1,2);
| ^
test.c:6:17: note: token 0 has y-location == 263200
1: 263264, 263264
In file included from test.c:1:
test.h:3:22: note: token 1 has x-location == y-location == 263264
3 | #define PLUS(A, B) A + B
| ^
2: 283712, 263328
test.c:6:19: note: token 2 has x-location == 283712
6 | int a = PLUS (1,2);
| ^
test.c:6:19: note: token 2 has y-location == 263328
3: 0, 0
cc1: note: token 3 has x-location == y-location == 0
4: 0, 0
cc1: note: token 4 has x-location == y-location == 0
5: 0, 0
cc1: note: token 5 has x-location == y-location == 0
6: 0, 0
cc1: note: token 6 has x-location == y-location == 0
MACRO 1: __GCC_IEC_559_COMPLEX (1 tokens)
location_t interval: 2147483646 <= loc < 2147483647
In file included from <command-line>:31:
/usr/include/stdc-predef.h:45:6: note: expansion point is location 180564
45 | # if __GCC_IEC_559_COMPLEX > 0
| ^~~~~~~~~~~~~~~~~~~~~
map->start_location: 2147483646
macro_locations:
0: 1, 1
<built-in>: note: token 0 has x-location == y-location == 1
MACRO 0: __GCC_IEC_559 (1 tokens)
location_t interval: 2147483647 <= loc < 2147483648
/usr/include/stdc-predef.h:37:6: note: expansion point is location 147788
37 | # if __GCC_IEC_559 > 0
| ^~~~~~~~~~~~~
map->start_location: 2147483647
macro_locations:
0: 1, 1
<built-in>: note: token 0 has x-location == y-location == 1
MAX_LOCATION_T
location_t interval: 2147483647 <= loc < 2147483648
AD-HOC LOCATIONS
location_t interval: 2147483648 <= loc < 4294967295
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^