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Some symbol names somehow depend on the source directory location #7133

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glandium opened this issue Jul 13, 2019 · 4 comments · Fixed by #7134
Closed

Some symbol names somehow depend on the source directory location #7133

glandium opened this issue Jul 13, 2019 · 4 comments · Fixed by #7134

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@glandium
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I've tried many different things, optimizations on, off, debug-info, no debug-info, and that made no difference. Here are steps to reproduce that "works" every time for me (using --release reduces the number of symbols affected, since so many are eliminated in this case):

$ cargo --version
cargo 1.36.0 (c4fcfb725 2019-05-15)
$ rustc --version
rustc 1.36.0 (a53f9df32 2019-07-03)
$ cargo new t1
$ cp -r t1 t2
$ cd t1
$ CARGO_INCREMENTAL=0 cargo rustc --release -- --remap-path-prefix=$PWD=. -C codegen-units=1
   Compiling t1 v0.1.0 (/tmp/t1)
    Finished release [optimized] target(s) in 0.29s
$ cd ../t2
$ CARGO_INCREMENTAL=0 cargo rustc --release -- --remap-path-prefix=$PWD=. -C codegen-units=1
   Compiling t1 v0.1.0 (/tmp/t2)
    Finished release [optimized] target(s) in 0.27s
$ cd ..
$ diffoscope t[12]/target/release/t1
--- t1/target/release/t1
+++ t2/target/release/t1
├── readelf --wide --symbols {}
│ @@ -129,20 +129,20 @@
│      41: 0000000000004180     0 FUNC    LOCAL  DEFAULT   14 deregister_tm_clones
│      42: 00000000000041b0     0 FUNC    LOCAL  DEFAULT   14 register_tm_clones
│      43: 00000000000041f0     0 FUNC    LOCAL  DEFAULT   14 __do_global_dtors_aux
│      44: 0000000000030038     1 OBJECT  LOCAL  DEFAULT   28 completed.7325
│      45: 000000000002e168     0 OBJECT  LOCAL  DEFAULT   23 __do_global_dtors_aux_fini_array_entry
│      46: 0000000000004230     0 FUNC    LOCAL  DEFAULT   14 frame_dummy
│      47: 000000000002e160     0 OBJECT  LOCAL  DEFAULT   22 __frame_dummy_init_array_entry
│ -    48: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS t1.akdfy859-cgu.0
│ -    49: 0000000000004270    71 FUNC    LOCAL  DEFAULT   14 _ZN2t14main17hc5d68b83d81d2494E
│ -    50: 0000000000004240     7 FUNC    LOCAL  DEFAULT   14 _ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h5d4bc421a6240ab3E
│ -    51: 0000000000004250     7 FUNC    LOCAL  DEFAULT   14 _ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17h5825211e365a5efdE
│ -    52: 0000000000004260     1 FUNC    LOCAL  DEFAULT   14 _ZN4core3ptr18real_drop_in_place17h5e90b097dfd8451cE
│ -    53: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS 45oartxzl9zxvu7a
│ +    48: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS t1.aywbp33t-cgu.0
│ +    49: 0000000000004270    71 FUNC    LOCAL  DEFAULT   14 _ZN2t14main17h18e047a624f74a19E
│ +    50: 0000000000004240     7 FUNC    LOCAL  DEFAULT   14 _ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17hbdbfcf746a94100cE
│ +    51: 0000000000004250     7 FUNC    LOCAL  DEFAULT   14 _ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17hd8c4386471704473E
│ +    52: 0000000000004260     1 FUNC    LOCAL  DEFAULT   14 _ZN4core3ptr18real_drop_in_place17h66f94376c5a38a4aE
│ +    53: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS 3d9navqc0k273olq
│      54: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS std.7lpsvnrb-cgu.0
│      55: 000000000002c7d4     0 NOTYPE  LOCAL  DEFAULT   19 GCC_except_table1000
│      56: 000000000002c800     0 NOTYPE  LOCAL  DEFAULT   19 GCC_except_table1002
│      57: 000000000002c81c     0 NOTYPE  LOCAL  DEFAULT   19 GCC_except_table1006
│      58: 000000000002ba48     0 NOTYPE  LOCAL  DEFAULT   19 GCC_except_table102
│      59: 000000000002c838     0 NOTYPE  LOCAL  DEFAULT   19 GCC_except_table1031
│      60: 000000000002c864     0 NOTYPE  LOCAL  DEFAULT   19 GCC_except_table1039
├── objdump --line-numbers --disassemble --demangle --reloc --section=.text {}
│ @@ -75,42 +75,42 @@
│  frame_dummy():
│      4230:	e9 7b ff ff ff       	jmpq   41b0 <register_tm_clones>
│      4235:	66 2e 0f 1f 84 00 00 	nopw   %cs:0x0(%rax,%rax,1)
│      423c:	00 00 00 
│      423f:	90                   	nop
│  
│  0000000000004240 <std::rt::lang_start::{{closure}}>:
│ -_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h5d4bc421a6240ab3E():
│ +_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17hbdbfcf746a94100cE():
│      4240:	50                   	push   %rax
│      4241:	ff 17                	callq  *(%rdi)
│      4243:	31 c0                	xor    %eax,%eax
│      4245:	59                   	pop    %rcx
│      4246:	c3                   	retq   
│      4247:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
│      424e:	00 00 
│  
│  0000000000004250 <core::ops::function::FnOnce::call_once{{vtable-shim}}>:
│ -_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17h5825211e365a5efdE():
│ +_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17hd8c4386471704473E():
│      4250:	50                   	push   %rax
│      4251:	ff 17                	callq  *(%rdi)
│      4253:	31 c0                	xor    %eax,%eax
│      4255:	59                   	pop    %rcx
│      4256:	c3                   	retq   
│      4257:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
│      425e:	00 00 
│  
│  0000000000004260 <core::ptr::real_drop_in_place>:
│ -_ZN4core3ptr18real_drop_in_place17h5e90b097dfd8451cE():
│ +_ZN4core3ptr18real_drop_in_place17h66f94376c5a38a4aE():
│      4260:	c3                   	retq   
│      4261:	66 2e 0f 1f 84 00 00 	nopw   %cs:0x0(%rax,%rax,1)
│      4268:	00 00 00 
│      426b:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
│  
│  0000000000004270 <t1::main>:
│ -_ZN2t14main17hc5d68b83d81d2494E():
│ +_ZN2t14main17h18e047a624f74a19E():
│      4270:	48 83 ec 38          	sub    $0x38,%rsp
│      4274:	48 8d 05 25 9f 02 00 	lea    0x29f25(%rip),%rax        
│      427b:	48 89 44 24 08       	mov    %rax,0x8(%rsp)
│      4280:	48 c7 44 24 10 01 00 	movq   $0x1,0x10(%rsp)
│      4287:	00 00 
│      4289:	48 c7 44 24 18 00 00 	movq   $0x0,0x18(%rsp)
│      4290:	00 00
├── readelf --wide --decompress --hex-dump=.strtab {}
│ @@ -5,33 +5,33 @@
│    0x00000020 005f5f64 6f5f676c 6f62616c 5f64746f .__do_global_dto
│    0x00000030 72735f61 75780063 6f6d706c 65746564 rs_aux.completed
│    0x00000040 2e373332 35005f5f 646f5f67 6c6f6261 .7325.__do_globa
│    0x00000050 6c5f6474 6f72735f 6175785f 66696e69 l_dtors_aux_fini
│    0x00000060 5f617272 61795f65 6e747279 00667261 _array_entry.fra
│    0x00000070 6d655f64 756d6d79 005f5f66 72616d65 me_dummy.__frame
│    0x00000080 5f64756d 6d795f69 6e69745f 61727261 _dummy_init_arra
│ -  0x00000090 795f656e 74727900 74312e61 6b646679 y_entry.t1.akdfy
│ -  0x000000a0 3835392d 6367752e 30005f5a 4e327431 859-cgu.0._ZN2t1
│ -  0x000000b0 346d6169 6e313768 63356436 38623833 4main17hc5d68b83
│ -  0x000000c0 64383164 32343934 45005f5a 4e337374 d81d2494E._ZN3st
│ +  0x00000090 795f656e 74727900 74312e61 79776270 y_entry.t1.aywbp
│ +  0x000000a0 3333742d 6367752e 30005f5a 4e327431 33t-cgu.0._ZN2t1
│ +  0x000000b0 346d6169 6e313768 31386530 34376136 4main17h18e047a6
│ +  0x000000c0 32346637 34613139 45005f5a 4e337374 24f74a19E._ZN3st
│    0x000000d0 64327274 31306c61 6e675f73 74617274 d2rt10lang_start
│    0x000000e0 32385f24 75376224 24753762 24636c6f 28_$u7b$$u7b$clo
│    0x000000f0 73757265 24753764 24247537 64243137 sure$u7d$$u7d$17
│ -  0x00000100 68356434 62633432 31613632 34306162 h5d4bc421a6240ab
│ -  0x00000110 3345005f 5a4e3463 6f726533 6f707338 3E._ZN4core3ops8
│ +  0x00000100 68626462 66636637 34366139 34313030 hbdbfcf746a94100
│ +  0x00000110 6345005f 5a4e3463 6f726533 6f707338 cE._ZN4core3ops8
│    0x00000120 66756e63 74696f6e 36466e4f 6e636534 function6FnOnce4
│    0x00000130 3063616c 6c5f6f6e 63652475 37622424 0call_once$u7b$$
│    0x00000140 75376224 76746162 6c652e73 68696d24 u7b$vtable.shim$
│ -  0x00000150 75376424 24753764 24313768 35383235 u7d$$u7d$17h5825
│ -  0x00000160 32313165 33363561 35656664 45005f5a 211e365a5efdE._Z
│ +  0x00000150 75376424 24753764 24313768 64386334 u7d$$u7d$17hd8c4
│ +  0x00000160 33383634 37313730 34343733 45005f5a 386471704473E._Z
│    0x00000170 4e34636f 72653370 74723138 7265616c N4core3ptr18real
│    0x00000180 5f64726f 705f696e 5f706c61 63653137 _drop_in_place17
│ -  0x00000190 68356539 30623039 37646664 38343531 h5e90b097dfd8451
│ -  0x000001a0 63450034 356f6172 74787a6c 397a7876 cE.45oartxzl9zxv
│ -  0x000001b0 75376100 7374642e 376c7073 766e7262 u7a.std.7lpsvnrb
│ +  0x00000190 68363666 39343337 36633561 33386134 h66f94376c5a38a4
│ +  0x000001a0 61450033 64396e61 76716330 6b323733 aE.3d9navqc0k273
│ +  0x000001b0 6f6c7100 7374642e 376c7073 766e7262 olq.std.7lpsvnrb
│    0x000001c0 2d636775 2e300047 43435f65 78636570 -cgu.0.GCC_excep
│    0x000001d0 745f7461 626c6531 30303000 4743435f t_table1000.GCC_
│    0x000001e0 65786365 70745f74 61626c65 31303032 except_table1002
│    0x000001f0 00474343 5f657863 6570745f 7461626c .GCC_except_tabl
│    0x00000200 65313030 36004743 435f6578 63657074 e1006.GCC_except
│    0x00000210 5f746162 6c653130 32004743 435f6578 _table102.GCC_ex
│    0x00000220 63657074 5f746162 6c653130 33310047 cept_table1031.G

The reason I opened this saying "depend on the source directory location" is that if I do cleanup everything, and do a new build in the same location, the result is identical:

$ cp -r t1 t3
$ cd t1
$ rm -rf target
$ CARGO_INCREMENTAL=0 cargo rustc --release -- --remap-path-prefix=$PWD=. -C codegen-units=1
   Compiling t1 v0.1.0 (/tmp/t1)
    Finished release [optimized] target(s) in 0.31s
$ cd ..
$ diffoscope t[13]/target/release/t1
@ehuss
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ehuss commented Jul 13, 2019

I think this is essentially #59542. The flags after cargo rustc are added to the hash for -C metadata which can affect symbol names.

This was fixed in 1.37 (now beta), but only when --remap-path-prefix is passed in via the RUSTFLAGS environment variable. Is there some reason you are passing it via cargo rustc instead of RUSTFLAGS?

We can easily add the "ignore --remap-path-prefix" to cargo rustc args. But as a workaround I suggest using RUSTFLAGS, and using beta (or waiting for it to release).

@glandium
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There's no particular reason I'm passing it via cargo rustc. I was just trying. But for consistency, it would be better if it worked when passed as an argument.

Anyways, I can confirm the following works:

$ cargo +beta --version
cargo 1.37.0-beta (4c1fa54d1 2019-06-24)
$ rustc +beta --version
rustc 1.37.0-beta.1 (178aa6611 2019-07-04)
$ cargo +beta new t1
     Created binary (application) `t1` package
$ cp -r t1 t2
$ cd t1
$ RUSTFLAGS="--remap-path-prefix=$PWD=." CARGO_INCREMENTAL=0 cargo +beta rustc --release -- -C codegen-units=1
   Compiling t1 v0.1.0 (/tmp/t1)
    Finished release [optimized] target(s) in 0.32s
$ cd ../t2
$ RUSTFLAGS="--remap-path-prefix=$PWD=." CARGO_INCREMENTAL=0 cargo +beta rustc --release -- -C codegen-units=1
   Compiling t1 v0.1.0 (/tmp/t2)
    Finished release [optimized] target(s) in 0.28s
$ cd ../
$ diffoscope t[12]/target/release/t1

@nagisa
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nagisa commented Jul 14, 2019

Not a rustc bug, closing as a duplicate of #6914

@nagisa nagisa closed this as completed Jul 14, 2019
@ehuss ehuss transferred this issue from rust-lang/rust Jul 14, 2019
@ehuss ehuss reopened this Jul 14, 2019
@ehuss
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ehuss commented Jul 14, 2019

Moving to cargo repo, and reopening since this isn't quite a duplicate.

@ehuss ehuss mentioned this issue Jul 14, 2019
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bors added a commit that referenced this issue Jul 14, 2019
@bors
Auto merge of #7134 - ehuss:remap-rustc, r=Eh2406
1140c52 
Also ignore remap-path-prefix in metadata for `cargo rustc`.

Also ignore `--remap-path-prefix` in `cargo rustc`.  Who knew that `BuildContext` had 3 sets of arguments?

Closes #7133
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Also ignore remap-path-prefix in metadata for cargo rustc. ehuss/cargo
3 participants
@ehuss @nagisa @glandium