Git merge can produce inconsistent Cargo.lock files #2302
Description
This is a reduction of what happened in servo/servo#9380.
- Consider a Cargo project in a git repository including
Cargo.lock. - One of the crates has a dependency, say on
matchesversion 0.1.1. - In a git branch
A, another crate gets a dependency onmatchesadded. The version stays 0.1.1. - In another branch
B,matchesis updated to 0.1.2 - The two branches are merged.
Cargo.locknow lists a"matches 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)"dependency from branch A, but has no[[package]]section for that version. (The one section formatcheswas updated to 0.1.2. in branchB.)- Cargo fails to deal with this inconsistency, everything is stuck until
Cargo.lockis fixed up manually.
Maybe Cargo could detect this kind of situation and repair it automatically?
This test script can be run in an empty directory:
#!/bin/sh
set -x
cargo new a --bin
cd a
echo 'b = {path = "./b"}' >> Cargo.toml
cargo new b
echo 'matches = "0.1"' >> b/Cargo.toml
cargo build
cargo update -p matches --precise 0.1.1
git add .
git commit -a -m "Initial"
git checkout -b update
cargo update -p matches --precise 0.1.2
git commit -a -m "Update"
git checkout master
echo 'matches = "0.1"' >> Cargo.toml
cargo build
git commit -a -m "Add dep"
git merge update --no-edit
cat Cargo.lock
cargo build
cd ..
rm -rf aHere is the output:
+ cargo new a --bin
+ cd a
+ echo 'b = {path = "./b"}'
+ cargo new b
+ echo 'matches = "0.1"'
+ cargo build
Updating registry `https://github.com/rust-lang/crates.io-index`
Compiling matches v0.1.2
Compiling b v0.1.0 (file:///tmp/z/a)
Compiling a v0.1.0 (file:///tmp/z/a)
+ cargo update -p matches --precise 0.1.1
Updating registry `https://github.com/rust-lang/crates.io-index`
Updating matches v0.1.2 -> v0.1.1
+ git add .
+ git commit -a -m Initial
[master (root-commit) 468750c] Initial
6 files changed, 43 insertions(+)
create mode 100644 .gitignore
create mode 100644 Cargo.lock
create mode 100644 Cargo.toml
create mode 100644 b/Cargo.toml
create mode 100644 b/src/lib.rs
create mode 100644 src/main.rs
+ git checkout -b update
Switched to a new branch 'update'
+ cargo update -p matches --precise 0.1.2
Updating registry `https://github.com/rust-lang/crates.io-index`
Updating matches v0.1.1 -> v0.1.2
+ git commit -a -m Update
[update 45230ad] Update
1 file changed, 2 insertions(+), 2 deletions(-)
+ git checkout master
Switched to branch 'master'
+ echo 'matches = "0.1"'
+ cargo build
Updating registry `https://github.com/rust-lang/crates.io-index`
Compiling matches v0.1.1
Compiling b v0.1.0 (file:///tmp/z/a)
Compiling a v0.1.0 (file:///tmp/z/a)
+ git commit -a -m 'Add dep'
[master d2ece92] Add dep
2 files changed, 2 insertions(+)
+ git merge update --no-edit
Auto-merging Cargo.lock
Merge made by the 'recursive' strategy.
Cargo.lock | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
+ cat Cargo.lock
[root]
name = "a"
version = "0.1.0"
dependencies = [
"b 0.1.0",
"matches 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
]
[[package]]
name = "b"
version = "0.1.0"
dependencies = [
"matches 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
]
[[package]]
name = "matches"
version = "0.1.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
+ cargo build
failed to select a version for `matches` (required by `a`):
all possible versions conflict with previously selected versions of `matches`
version 0.1.2 in use by matches v0.1.2
possible versions to select: 0.1.1
+ cd ..
+ rm -rf a