Adding upstream version 1.65.0+dfsg1.upstream/1.65.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/tools/clippy/src/docs/unnecessary_join.txt b/src/tools/clippy/src/docs/unnecessary_join.txt
new file mode 100644
index 000000000..ee4e78601
--- /dev/null
+++ b/src/tools/clippy/src/docs/unnecessary_join.txt
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+### What it does
+Checks for use of `.collect::<Vec<String>>().join("")` on iterators.
+
+### Why is this bad?
+`.collect::<String>()` is more concise and might be more performant
+
+### Example
+```
+let vector = vec!["hello",  "world"];
+let output = vector.iter().map(|item| item.to_uppercase()).collect::<Vec<String>>().join("");
+println!("{}", output);
+```
+The correct use would be:
+```
+let vector = vec!["hello",  "world"];
+let output = vector.iter().map(|item| item.to_uppercase()).collect::<String>();
+println!("{}", output);
+```
+### Known problems
+While `.collect::<String>()` is sometimes more performant, there are cases where
+using `.collect::<String>()` over `.collect::<Vec<String>>().join("")`
+will prevent loop unrolling and will result in a negative performance impact.
+
+Additionally, differences have been observed between aarch64 and x86_64 assembly output,
+with aarch64 tending to producing faster assembly in more cases when using `.collect::<String>()`
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