ncp11 .​note.​go.​buildid isn't reproducible

[JeremyRand]

Steps to reproduce

1. Apply the rbm patch from https://trac.torproject.org/projects/tor/ticket/31264 , which fixes an unrelated reproducibility bug.
2. Run the following twice: ./rbm/rbm build ncp11 --target release --target ncdns-linux-x86_64
3. Compare the outputs in diffoscope.

Expected results

Files should be identical.

Observed results

--- a/ncp11-0.0.1-linux-x86_64-7197ac.tar.gz
+++ b/ncp11-0.0.1-linux-x86_64-7197ac.tar.gz
├── ncp11-0.0.1-linux-x86_64-7197ac.tar
│ ├── ./libncp11.so
│ │ ├── readelf --wide --notes {}
│ │ │ @@ -1,8 +1,8 @@
│ │ │  
│ │ │  Displaying notes found in: .note.go.buildid
│ │ │    Owner                 Data size	Description
│ │ │ -  Go                   0x00000053	Unknown note type: (0x00000004)	   description data: 78 72 67 71 62 7a 62 2d 4d 45 6d 2d 31 37 69 4b 50 57 66 75 2f 6f 76 46 63 4e 48 6a 32 46 6d 4d 55 71 44 66 52 4a 57 55 4f 2f 4f 32 39 39 57 30 76 4f 4c 47 2d 66 53 61 77 55 62 6d 36 39 2f 68 53 77 6a 4a 6f 70 72 51 4f 30 34 43 69 41 48 4b 78 4c 47 
│ │ │ +  Go                   0x00000053	Unknown note type: (0x00000004)	   description data: 78 72 67 71 62 7a 62 2d 4d 45 6d 2d 31 37 69 4b 50 57 66 75 2f 6f 76 46 63 4e 48 6a 32 46 6d 4d 55 71 44 66 52 4a 57 55 4f 2f 4f 32 39 39 57 30 76 4f 4c 47 2d 66 53 61 77 55 62 6d 36 39 2f 30 37 5a 55 44 54 4b 44 75 6d 55 6b 31 54 6e 36 38 64 4c 6a 
│ │ │  
│ │ │  Displaying notes found in: .note.gnu.gold-version
│ │ │    Owner                 Data size	Description
│ │ │    GNU                  0x00000009	NT_GNU_GOLD_VERSION (gold version)	    Version: gold 1.16
│ │ ├── readelf --wide --version-info {}
│ │ │ @@ -84,15 +84,15 @@
│ │ │    140:   1 (*global*)      1 (*global*)      1 (*global*)      1 (*global*)   
│ │ │    144:   1 (*global*)      1 (*global*)      1 (*global*)      1 (*global*)   
│ │ │    148:   1 (*global*)      1 (*global*)      1 (*global*)      1 (*global*)   
│ │ │    14c:   1 (*global*)      1 (*global*)   
│ │ │  
│ │ │  Version definition section '.gnu.version_d' contains 1 entry:
│ │ │    Addr: 0x0000000000005330  Offset: 0x005330  Link: 3 (.dynstr)
│ │ │ -  000000: Rev: 1  Flags: BASE  Index: 1  Cnt: 1  Name: /tmp/go-build832923583/b001/exe/a.out
│ │ │ +  000000: Rev: 1  Flags: BASE  Index: 1  Cnt: 1  Name: /tmp/go-build272286888/b001/exe/a.out
│ │ │  
│ │ │  Version needs section '.gnu.version_r' contains 3 entries:
│ │ │   Addr: 0x000000000000534c  Offset: 0x00534c  Link: 3 (.dynstr)
│ │ │    000000: Version: 1  File: libc.so.6  Cnt: 3
│ │ │    0x0010:   Name: GLIBC_2.2.5  Flags: none  Version: 2
│ │ │    0x0020:   Name: GLIBC_2.3.4  Flags: none  Version: 3
│ │ │    0x0030:   Name: GLIBC_2.4  Flags: none  Version: 4
│ │ ├── readelf --wide --decompress --hex-dump=.dynstr {}
│ │ │ @@ -1,15 +1,15 @@
│ │ │  
│ │ │  Hex dump of section '.dynstr':
│ │ │    0x000021f0 0072756e 74696d65 2e746c73 67005f5f .runtime.tlsg.__
│ │ │    0x00002200 676d6f6e 5f737461 72745f5f 00736967 gmon_start__.sig
│ │ │    0x00002210 69736d65 6d626572 00474c49 42435f32 ismember.GLIBC_2
│ │ │    0x00002220 2e322e35 006c6962 632e736f 2e36002f .2.5.libc.so.6./
│ │ │ -  0x00002230 746d702f 676f2d62 75696c64 38333239 tmp/go-build8329
│ │ │ -  0x00002240 32333538 332f6230 30312f65 78652f61 23583/b001/exe/a
│ │ │ +  0x00002230 746d702f 676f2d62 75696c64 32373232 tmp/go-build2722
│ │ │ +  0x00002240 38363838 382f6230 30312f65 78652f61 86888/b001/exe/a
│ │ │    0x00002250 2e6f7574 005f696e 69740073 69676164 .out._init.sigad
│ │ │    0x00002260 64736574 005f6669 6e690073 69676163 dset._fini.sigac
│ │ │    0x00002270 74696f6e 006c6962 70746872 6561642e tion.libpthread.
│ │ │    0x00002280 736f2e30 00756e73 6574656e 76005f49 so.0.unsetenv._I
│ │ │    0x00002290 544d5f64 65726567 69737465 72544d43 TM_deregisterTMC
│ │ │    0x000022a0 6c6f6e65 5461626c 65007369 67656d70 loneTable.sigemp
│ │ │    0x000022b0 74797365 74005f49 544d5f72 65676973 tyset._ITM_regis

Other info

This seems to be caused by golang/go#33772 . The recommendation in that issue is to pass -ldflags=-buildid= to go build.

[JeremyRand]

Filed bug with Tor at http://ea5faa5po25cf7fb.onion/projects/tor/ticket/31691