Method definition overwrite warning warns erronously on call overloads.

[KristofferC]

Putting

struct Foo end
struct Bar end

for t in (Foo, Bar)
    @eval (::$t)(x) = 1
end

in a a package and using the --warn-overwrite=yes option, Julia will warn with

WARNING: Method definition Any(Any) in module Dup at /Users/kristoffercarlsson/julia/Dup/src/Dup.jl:9 overwritten on the same line (check for duplicate calls to `include`).
WARNING: Method definition Any(Any) in module Dup at /Users/kristoffercarlsson/julia/Dup/src/Dup.jl:9 overwritten on the same line (check for duplicate calls to `include`).

I'm guessing this if from #36609.

Looking at some random PkgEval log there are thousands of these warnings, e.g. https://s3.amazonaws.com/julialang-reports/nanosoldier/pkgeval/by_hash/aa3a19f_vs_dd12291/ADCME.1.7.0-beta1-ef3861cb06.log:

WARNING: Method definition Any(Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:81 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any, Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:98 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:98 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:103 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:110 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any, Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:114 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:95 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any...) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/pyfncall.jl:86 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:82 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition Any(Any) in module PyCall at /home/pkgeval/.julia/packages/PyCall/BD546/src/io.jl:94 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

cc @vtjnash

[KristofferC]

Also, it shows e.g:

WARNING: Method definition (::ForwardDiff.InnerGradientForHess{R, C, F})(Any, Any) in module ForwardDiff at /home/pkgeval/.julia/packages/ForwardDiff/QOqCN/src/hessian.jl:48 overwritten on the same line (check for duplicate calls to `include`).
  ** incremental compilation may be fatally broken for this module **

at https://github.com/JuliaDiff/ForwardDiff.jl/blob/909976d719fdbd5fec91a159c6e2d808c45a770f/src/hessian.jl#L48-L53

but I don't understand that.

[KristofferC]

Dup of #41156 perhaps?