string fmt bug on nightly

[vitiral]

I develop artifact on nightly and publish using stable, so I am sensitive to changes that happen in nightly but not stable.

Right now the fmt functionality seems to be partially broken on nightly. this commit fails the unit test (running cargo test) cmd::tests::test_ls::test_cmd_check:

note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.                                                                                                                            
stack backtrace:                                                                                                                                                                                                   
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace                                                                                                                                                     
             at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49                                                                                                                                        
   1: std::sys_common::backtrace::_print                                                                                                                                                                           
             at /checkout/src/libstd/sys_common/backtrace.rs:71                                                                                                                                                   
   2: std::panicking::default_hook::{{closure}}                                                                                                                                                                    
             at /checkout/src/libstd/sys_common/backtrace.rs:60                                                                                                                                                    
             at /checkout/src/libstd/panicking.rs:380                                                                                                                                                              
   3: std::panicking::default_hook                                                                                                                                                                                 
             at /checkout/src/libstd/panicking.rs:390                                                                                                                                                             
   4: std::panicking::rust_panic_with_hook                                                                                                                                                                        
             at /checkout/src/libstd/panicking.rs:610                                                    
   5: std::panicking::begin_panic                                                                                                                                                                                  
             at /checkout/src/libstd/panicking.rs:571                                                                                                                                                              
   6: std::panicking::begin_panic_fmt                                                                                                                                                                              
             at /checkout/src/libstd/panicking.rs:521                                                                                                                                                              
   7: artifact_app::cmd::tests::test_ls::test_cmd_check                                                                                                                                                            
             at src/cmd/tests/test_ls.rs:260                                                                                                                                                                      
   8: <F as test::FnBox<T>>::call_box                                                                                                                                                                              
             at /checkout/src/libtest/lib.rs:1477                                                                                                                                                                  
             at /checkout/src/libcore/ops/function.rs:143                                                                                                                                                          
             at /checkout/src/libtest/lib.rs:138                                                                                                                                                                   
   9: __rust_maybe_catch_panic                                                                                                                                                                                     
             at /checkout/src/libpanic_unwind/lib.rs:98                                                                                                                                                            
                                                                                             
                                                                                                                                                                                                                   
failures:                                                                                                                                                                                                          
    cmd::tests::test_ls::test_cmd_check                                                                                                                                                                            
                                                                                                                                                                                                                   
test result: FAILED. 34 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out                                                                                                                                    
                                                                                                                                                                                                                  
error: test failed, to rerun pass '--lib'               

The test prints the expected/result. That printout is:

Debug Result:                                                                                                                                                                                                      
                                                                                                                                                                                                                  
Found partof names that do not exist:                                                                                                                                                                              
- REQ-invalid-parts [../../reqs/foo.toml]: {REQ-DNE}                                                                                                                                                               
                                                                                                                                                                                                                   
Artifacts partof contains at least one recursive reference:                                                                                                                                                        
- SPC-unresolvable              : [SPC-UNRESOLVABLE-1-1]                                                                                                                                                          
- SPC-unresolvable-1            : [SPC-UNRESOLVABLE]                                                                                                                                                              
- SPC-unresolvable-1-1          : [SPC-UNRESOLVABLE-1]                                                   
                                                                                                                                                                                                                   
Found implementation links in the code that do not exist:                                                                                                                                                          
- ../../fake:                                                                                                                                                                                                      
  - [42] SPC-dne                                                                                                                                                                                                   
                                                                                                                                                                                                                   
Hanging artifacts found (top-level but not partof a higher type):                                                                                                                                                 
- ../../reqs/foo.toml: TST-line                                                                                                                                                                                    
                                                                                                                                                                                                                   
Repr Result:                                                                                                                                                                                                       
\x1b[1;31m\nFound partof names that do not exist:\n\x1b[0m\x1b[31m- REQ-invalid-parts [../../reqs/foo.toml]: {REQ-DNE}\n\x1b[0m\x1b[1;31m\nArtifacts partof contains at least one recursive reference:\n\x1b[0m- SP
C-unresolvable              : [SPC-UNRESOLVABLE-1-1]\n- SPC-unresolvable-1            : [SPC-UNRESOLVABLE]\n- SPC-unresolvable-1-1          : [SPC-UNRESOLVABLE-1]\n\x1b[1;31m\nFound implementation links in the c
ode that do not exist:\n\x1b[0m\x1b[31m- ../../fake:\n\x1b[0m\x1b[31m  - [42]\x1b[0m SPC-dne\n\x1b[1;31m\nHanging artifacts found (top-level but not partof a higher type):\n\x1b[0m- ../../reqs/foo.toml: TST-line
\n\n                                                                                         
--Result Repr DONE

Debug Expected:                                                                                                                                                                                                    
                                                                                                                                                                                                                   
Found partof names that do not exist:                                                                                                                                                                              
- REQ-invalid-parts [../../reqs/foo.toml]: {REQ-DNE}                                                                                                                                                               
                                                                                                                                                                                                                  
Artifacts partof contains at least one recursive reference:                                                                                                                                                        
- SPC-unresolvable              : [SPC-UNRESOLVABLE-1-1]                                                                                                                                                           
- SPC-unresolvable-1            : [SPC-UNRESOLVABLE]                                                                                                                                                               
- SPC-unresolvable-1-1          : [SPC-UNRESOLVABLE-1]                                                                                                                                                             
                                                                                                                                                                                                                  
Found implementation links in the code that do not exist:                                                                                                                                                         
- ../../fake:                                                                                            
  - [42] SPC-dne                                                                                                                                                                                                   
                                                                                                                                                                                                                   
Hanging artifacts found (top-level but not partof a higher type):                                                                                                                                                  
- ../../reqs/foo.toml           : TST-line                                                                                                                                                                         
                                                                                                                                                                                                                   
Repr Expected:                                                                                                                                                                                                    
\x1b[1;31m\nFound partof names that do not exist:\n\x1b[0m\x1b[31m- REQ-invalid-parts [../../reqs/foo.toml]: {REQ-DNE}\n\x1b[0m\x1b[1;31m\nArtifacts partof contains at least one recursive reference:\n\x1b[0m- SP
C-unresolvable              : [SPC-UNRESOLVABLE-1-1]\n- SPC-unresolvable-1            : [SPC-UNRESOLVABLE]\n- SPC-unresolvable-1-1          : [SPC-UNRESOLVABLE-1]\n\x1b[1;31m\nFound implementation links in the c
ode that do not exist:\n\x1b[0m\x1b[31m- ../../fake:\n\x1b[0m\x1b[31m  - [42]\x1b[0m SPC-dne\n\x1b[1;31m\nHanging artifacts found (top-level but not partof a higher type):\n\x1b[0m- ../../reqs/foo.toml          
 : TST-line\n\n                                                                                                                                                                                                    
--Expected Repr DONE

The difference between the two (that I can spot) is these two lines:

# result
- ../../reqs/foo.toml: TST-line
# expected                                                                                                                                         
- ../../reqs/foo.toml           : TST-line

I went into the code to find what generates this formatting, it is in src/cmd/check.rs line 234:

            write!(
                msg,
                "- {:<30}: {}\n",
                utils::relative_path(p, cwd).display(),
                h
            ).unwrap();

Oddly, there is a very similar line of code that is used to generate the Artifacts partof contains at least one recursive reference: section of the output. That line of code is in the same file, line 159:

write!(msg, "- {:<30}: {:?}\n", name.to_string(), partof).unwrap();

That line works, the other one doesn't. Why? That I have no clue about...

Meta

This passes (running cargo test) on

$ rustc --version --verbose   
rustc 1.19.0 (0ade33941 2017-07-17)                 
binary: rustc             
commit-hash: 0ade339411587887bf01bcfa2e9ae4414c8900d4                                                    
commit-date: 2017-07-17   
host: x86_64-unknown-linux-gnu                      
release: 1.19.0           
LLVM version: 4.0

And fails on

$ rustc --version --verbose                                                                                                                                                           
rustc 1.21.0-nightly (cbbe17aa7 2017-08-07)                                                                                                                                                                       
binary: rustc
commit-hash: cbbe17aa7f13f9568a652c2180de03fa6881b86a
commit-date: 2017-08-07
host: x86_64-unknown-linux-gnu
release: 1.21.0-nightly
LLVM version: 4.0

# and fails for this as well
$ rustc --version                                                                                                                                                                     
rustc 1.21.0-nightly (b75d1f0ce 2017-08-02)

[vitiral]

it also passes for

rustc --version                                                                                                                                                                     
rustc 1.19.0-nightly (fe7227f6c 2017-06-16)

[ExpHP]

bisection log

rustc 1.20.0-nightly (d84693b93 2017-07-09) ... test FAILED
rustc 1.20.0-nightly (37849a002 2017-06-30) ... test FAILED
rustc 1.19.0-nightly (04145943a 2017-06-19) ... test FAILED
rustc 1.19.0-nightly (78d8416ca 2017-06-17) ... test FAILED

[ExpHP]

...and that exhausts the nightlies. We're down to

fe7227f...78d8416

[ollie27]

It looks like this was caused by #42613 cc @stepancheg. The Display impl for Path no longer takes formatting parameters into account. For example:

println!("a{:#<5}b", ::std::path::Path::new("").display());

Prints a#####b on stable and ab on beta and nightly.

[vitiral]

thanks for diagnosing. It would be worth adding some unit tests around Path formatting as I imagine it is depended upon by a fair number of people (myself included!)

[alexcrichton]

I've sent a PR for this at #43830