CODEWITHSUNDEEP
rustrust-cargo
Kos
Kos

Reputation: 1778

Cargo version dependency picking algorithm?

Is that the same

[dependencies]
for_each = "0.1"

as

[dependencies]
for_each = "0.1.2"

And

[dependencies]
for_each = "~0.1"

From description, it looks like the same, but from experimentation I am getting inconsistent results.

What is the subtle difference between those 3 variants of requiring dependencies?

It looks like ranges are:

0.1    :=  >=0.1.0, <0.2.0
0.1.2  :=  >=0.1.2, <0.2.0
~0.1   := >=0.1.0, <0.2.0

Right?

From these, it's clear that 0.1 and ~0.1 have the same range. But I encountered a situation when 0.1 and ~0.1 give very different results. Some subtle difference beyond ranges exists, and I don't understand what is that.

Upvotes: 1

Views: 154

Answers (1)

Finomnis
Finomnis

Reputation: 22371

0.1    :=  >=0.1.0, <0.2.0
0.1.2  :=  >=0.1.2, <0.2.0
~0.1   :=  >=0.1.0, <0.2.0

More details at https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html.

Without the tilde, version compatibility is determined following the SemVer rules. Cargo extended SemVer for <1.0.0 versions:

Cargo considers 0.x.y to be compatible with 0.x.z, where y ≥ z and x > 0.

On the other hand, Tilde Requirements seems to be something defined by Cargo:

Tilde requirements specify a minimal version with some ability to update. If you specify a major, minor, and patch version or only a major and minor version, only patch-level changes are allowed. If you only specify a major version, then minor- and patch-level changes are allowed.

Upvotes: 1

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