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Set max_methods 1 for several IO functions #60391

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Set max_methods 1 for several IO functions #60391

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b65bc9e
Set max_methods 1 for several IO functions
jakobnissen Dec 16, 2025
672cce5
type assert return value of `write` in a place where it fails to infer
KristofferC Dec 16, 2025
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3 changes: 3 additions & 0 deletions base/coreio.jl
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Original file line number Diff line number Diff line change
@@ -1,5 +1,8 @@
# This file is a part of Julia. License is MIT: https://julialang.org/license

function print end
typeof(print).name.max_methods = UInt8(1)

print(x) = print(stdout, x)
print(x1, x2) = print(stdout, x1, x2)
println(x) = print(stdout, x, "\n")
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11 changes: 11 additions & 0 deletions base/io.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@ false
```
"""
function isopen end
typeof(isopen).name.max_methods = UInt8(1)

"""
close(io::IO)
Expand All @@ -83,6 +84,7 @@ closed IO does not cause undefined behaviour.
See also: [`isopen`](@ref)
"""
function close end
typeof(close).name.max_methods = UInt8(1)

"""
closewrite(stream)
Expand Down Expand Up @@ -110,6 +112,7 @@ julia> read(io, String)
```
"""
function closewrite end
typeof(closewrite).name.max_methods = UInt8(1)

"""
flush(io::IO)
Expand All @@ -119,6 +122,7 @@ This has a default implementation `flush(::IO) = nothing`, so may be called
in generic IO code.
"""
function flush end
typeof(flush).name.max_methods = UInt8(1)

"""
bytesavailable(io)
Expand All @@ -134,6 +138,7 @@ julia> bytesavailable(io)
```
"""
function bytesavailable end
typeof(bytesavailable).name.max_methods = UInt8(1)

"""
readavailable(stream)
Expand All @@ -147,8 +152,11 @@ data has already been buffered. The result is a `Vector{UInt8}`.
should generally be used instead.
"""
function readavailable end
typeof(readavailable).name.max_methods = UInt8(1)

function isexecutable end
typeof(isexecutable).name.max_methods = UInt8(1)


"""
isreadable(io)::Bool
Expand Down Expand Up @@ -219,6 +227,7 @@ true
```
"""
function eof end
typeof(eof).name.max_methods = UInt8(1)

function copy end
function wait_readnb end
Expand Down Expand Up @@ -318,6 +327,7 @@ Base.RefValue{MyStruct}(MyStruct(42.0))
```
"""
function write end
typeof(write).name.max_methods = UInt8(1)

read(s::IO, ::Type{UInt8}) = error(typeof(s)," does not support byte I/O")
write(s::IO, x::UInt8) = error(typeof(s)," does not support byte I/O")
Expand Down Expand Up @@ -530,6 +540,7 @@ read(filename::AbstractString, ::Type{T}) where {T} = open(io->read(io, T), conv
Read binary data from an I/O stream or file, filling in `array`.
"""
function read! end
typeof(read!).name.max_methods = UInt8(1)
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@nsajko nsajko Jan 30, 2026

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What happens if a method of read! gets defined and a method instance gets compiled/inferred before you change max_methods here? Would it cause miscompilation?


read!(filename::AbstractString, a) = open(io->read!(io, a), convert(String, filename)::String)

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2 changes: 1 addition & 1 deletion base/strings/annotated_io.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ end

write(io::AnnotatedIOBuffer, c::AnnotatedChar) =
write(io, AnnotatedString(string(c), [(region=1:ncodeunits(c), a...) for a in c.annotations]))
write(io::AnnotatedIOBuffer, x::AbstractString) = write(io.io, x)
write(io::AnnotatedIOBuffer, x::AbstractString) = write(io.io, x)::Int
write(io::AnnotatedIOBuffer, s::Union{SubString{String}, String}) = write(io.io, s)
write(io::AnnotatedIOBuffer, b::UInt8) = write(io.io, b)

Expand Down