Bug 28108 - [gcc-11] FAIL: gdb.base/langs.exp: up to foo in langs.exp
Summary: [gcc-11] FAIL: gdb.base/langs.exp: up to foo in langs.exp
Status: RESOLVED FIXED
Alias: None
Product: gdb
Classification: Unclassified
Component: testsuite (show other bugs)
Version: HEAD
: P2 normal
Target Milestone: 12.1
Assignee: Not yet assigned to anyone
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-07-20 05:18 UTC by Tom de Vries
Modified: 2023-10-25 14:24 UTC (History)
0 users

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Description Tom de Vries 2021-07-20 05:18:36 UTC 
When running with gcc-11 (with -gdwarf-5 default), I run into:
...
FAIL: gdb.base/langs.exp: up to foo in langs.exp
FAIL: gdb.base/langs.exp: up to cppsub_ in langs.exp
FAIL: gdb.base/langs.exp: up to fsub in langs.exp
...

In more detail:
...
(gdb) up^M
#1  0x0000000000400520 in foo__Fi (x=10000) at /home/vries/gdb_versions/devel/build/gdb/testsuite/langs2.cxx:5^M
5         return csub (x / 2);^M
(gdb) FAIL: gdb.base/langs.exp: up to foo in langs.exp
...
while with say -gdwarf-4 we have:
...
(gdb) up^M
#1  0x0000000000400520 in foo__Fi (x=10000) at langs2.cxx:5^M
5         return csub (x / 2);^M
(gdb) PASS: gdb.base/langs.exp: up to foo in langs.exp  
...

The difference is "/home/vries/gdb_versions/devel/build/gdb/testsuite/langs2.cxx" vs "langs2.cxx".
Comment 1 Tom de Vries 2021-07-20 05:47:18 UTC 
With -gdwarf-4, we have:
...
 <0><243>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <244>   DW_AT_producer    : (indirect string, offset: 0x208): GNU C17 11.1.1 20210625 [revision 62bbb113ae68a7e724255e17143520735bcb9ec9] -mtune=generic -march=x86-64 -gdwarf-4 -fno-stack-protector
    <248>   DW_AT_language    : 12      (ANSI C99)
    <249>   DW_AT_name        : (indirect string, offset: 0x34d): /home/vries/gdb_versions/devel/src/gdb/testsuite/gdb.base/langs2.c
    <24d>   DW_AT_comp_dir    : (indirect string, offset: 0x1d0): /home/vries/gdb_versions/devel/build/gdb/testsuite
    <251>   DW_AT_low_pc      : 0x400502
    <259>   DW_AT_high_pc     : 0x3b
    <261>   DW_AT_stmt_list   : 0x20f
...
and at 0x20f:
...
 The Directory Table is empty.

 The File Name Table (offset 0x22c):
  Entry Dir     Time    Size    Name
  1     0       0       0       langs2.cxx

...

With -gdwarf-5, we have:
...
 <0><242>: Abbrev Number: 2 (DW_TAG_compile_unit)
    <243>   DW_AT_producer    : (indirect string, offset: 0x1d0): GNU C17 11.1.1 20210625 [revision 62bbb113ae68a7e724255e17143520735bcb9ec9] -mtune=generic -march=x86-64 -gdwarf-5 -fno-stack-protector
    <247>   DW_AT_language    : 29      (C11)
    <248>   DW_AT_name        : (indirect line string, offset: 0xfc): /home/vries/gdb_versions/devel/src/gdb/testsuite/gdb.base/langs2.c
    <24c>   DW_AT_comp_dir    : (indirect line string, offset: 0x0): /home/vries/gdb_versions/devel/build/gdb/testsuite
    <250>   DW_AT_low_pc      : 0x400502
    <258>   DW_AT_high_pc     : 0x3b
    <260>   DW_AT_stmt_list   : 0x1b4
...
and at 0x1b4:
...
 The Directory Table (offset 0x1d6, lines 1, columns 1):
  Entry Name
  0     (indirect line string, offset: 0x0): /home/vries/gdb_versions/devel/build/gdb/testsuite

 The File Name Table (offset 0x1e0, lines 2, columns 2):
  Entry Dir     Name
  0     0       (indirect line string, offset: 0xfc): /home/vries/gdb_versions/devel/src/gdb/testsuite/gdb.base/langs2.c
  1     0       (indirect line string, offset: 0x13f): langs2.cxx
...

So the difference seems to be that the directory and file entries 0 are implicit in dwarf-4, and explicit in dwarf-5.
Comment 2 Tom de Vries 2021-07-20 11:03:09 UTC 
Posted RFC: https://sourceware.org/pipermail/gdb-patches/2021-July/181031.html
Comment 3 Tom de Vries 2023-10-25 14:24:23 UTC 
Fixed by commit d8504344d47 ("Fix some failures in langs.exp").