Rollup merge of #30144 - pjungwir:clarify-semver-rules, r=steveklabnik

The documentation shows this:

    [dependencies]

    rand="0.3.0"

and says it allows any version compatible with 0.3.0, but then it says, "If we wanted to use only 0.3.0 exactly, we could use `=0.3.0`." That is very easy to misunderstand, so hopefully this PR will help others not to be as confused as me. :-)

1 files changed, 7 insertions, 3 deletions

diff --git a/src/doc/book/guessing-game.md b/src/doc/book/guessing-game.md
index ef829c65558..0f9bc80af98 100644
--- a/src/doc/book/guessing-game.md
+++ b/src/doc/book/guessing-game.md
@@ -357,9 +357,13 @@ Cargo uses the dependencies section to know what dependencies on external
 crates you have, and what versions you require. In this case, we’ve specified version `0.3.0`,
 which Cargo understands to be any release that’s compatible with this specific version.
 Cargo understands [Semantic Versioning][semver], which is a standard for writing version
-numbers. If we wanted to use only `0.3.0` exactly, we could use `=0.3.0`. If we
-wanted to use the latest version we could use `*`; We could use a range of
-versions. [Cargo’s documentation][cargodoc] contains more details.
+numbers. A bare number like above is actually shorthand for `^0.3.0`,
+meaning "anything compatible with 0.3.0".
+If we wanted to use only `0.3.0` exactly, we could say `rand="=0.3.0"`
+(note the two equal signs).
+And if we wanted to use the latest version we could use `*`.
+We could also use a range of versions.
+[Cargo’s documentation][cargodoc] contains more details.
 
 [semver]: http://semver.org
 [cargodoc]: http://doc.crates.io/crates-io.html