fix(rust): support not installed toolchain

resolves #6645

Author: JanDeDobbeleer

src/segments/rust.go

@@ -14,7 +14,7 @@ func (r *Rust) Enabled() bool {
 		{
 			executable: "rustc",
 			args:       []string{"--version"},
-			regex:      `rustc (?P<version>((?P<major>[0-9]+).(?P<minor>[0-9]+).(?P<patch>[0-9]+))(-(?P<prerelease>[a-z]+))?)(( \((?P<buildmetadata>[0-9a-f]+ [0-9]+-[0-9]+-[0-9]+)\))?)`,
+			regex:      `(rust version|rustc) (?P<version>((?P<major>[0-9]+).(?P<minor>[0-9]+).(?P<patch>[0-9]+))(-(?P<prerelease>[a-z]+))?)(( \((?P<buildmetadata>[0-9a-f]+ [0-9]+-[0-9]+-[0-9]+)\))?)`, //nolint:lll
 		},
 	}
 

src/segments/rust_test.go

@@ -16,6 +16,25 @@ func TestRust(t *testing.T) {
 		{Case: "Rust 1.64.0", ExpectedString: "1.64.0", Version: "rustc 1.64.0"},
 		{Case: "Rust 1.53.0", ExpectedString: "1.53.0", Version: "rustc 1.53.0 (4369396ce 2021-04-27)"},
 		{Case: "Rust 1.66.0", ExpectedString: "1.66.0-nightly", Version: "rustc 1.66.0-nightly (01af5040f 2022-10-04)"},
+		{
+			Case:           "Toolchain not installed",
+			ExpectedString: "1.81.0",
+			Version: ` info: syncing channel updates for '1.81.0-x86_64-pc-windows-msvc'
+    info: latest update on 2024-09-05, rust version 1.81.0 (eeb90cda1 2024-09-04)
+    info: downloading component 'cargo'
+    info: downloading component 'clippy'
+    info: downloading component 'rust-analyzer'
+    info: downloading component 'rust-src'
+    info: downloading component 'rust-std'
+    info: downloading component 'rustc'
+    info: downloading component 'rustfmt'
+    info: installing component 'cargo'
+    info: installing component 'clippy'
+    info: installing component 'rust-analyzer'
+    info: installing component 'rust-src'
+    info: installing component 'rust-std'
+    info: installing component 'rustc'`,
+		},
 	}
 	for _, tc := range cases {
 		params := &mockedLanguageParams{