perf(lsp): compile naming-diagnostic regexes once, not per call

lspNamingDiagnostic recompiled 3 constant regexes on every call; LSP runs
diagnostics on every document change, so regexp.compile was ~67% of
LSPComputeDiagnostics's allocations. Hoisted to package-level vars.
LSPComputeDiagnostics: 186->47 allocs/op, 23922->8475 B/op, 12162->6061 ns/op.
Behaviour byte-identical (LSP tests green).

Co-Authored-By: Virgil <virgil@lethean.io>

Author: Snider

lsp.go

@@ -525,22 +525,26 @@ func lspSporDiagnostic(uri string, content []byte) []LSPDiagnostic {
 	return diags
 }
 
+// lspNaming{Top,Method,Test}Re are compiled once at package init. The
+// patterns are constant, and LSP runs diagnostics on every document
+// change — recompiling them per call made regexp.compile ~67% of
+// LSPComputeDiagnostics's allocations. Hoisting cuts ~150 allocs/call.
+var (
+	lspNamingTopRe    = Regex(`^func ([A-Za-z][A-Za-z0-9_]*)\s*[\[(]`).Value.(*Regexp)
+	lspNamingMethodRe = Regex(`^func \([^)]*?\*?([A-Za-z][A-Za-z0-9_]*)(?:\[[^\]]+\])?\) ([A-Za-z][A-Za-z0-9_]*)\s*[\[(]`).Value.(*Regexp)
+	lspNamingTestRe   = Regex(`^func (Test[A-Za-z0-9_]+)\s*\(`).Value.(*Regexp)
+)
+
 // lspNamingDiagnostic flags production symbols that do not have the
 // Test*_{Symbol}_{Good,Bad,Ugly} triplet in the same directory's tests.
 func lspNamingDiagnostic(uri string, content []byte) []LSPDiagnostic {
 	if !HasSuffix(uri, ".go") || HasSuffix(uri, "_test.go") {
 		return nil
 	}
 
-	topResult := Regex(`^func ([A-Za-z][A-Za-z0-9_]*)\s*[\[(]`)
-	methodResult := Regex(`^func \([^)]*?\*?([A-Za-z][A-Za-z0-9_]*)(?:\[[^\]]+\])?\) ([A-Za-z][A-Za-z0-9_]*)\s*[\[(]`)
-	testResult := Regex(`^func (Test[A-Za-z0-9_]+)\s*\(`)
-	if !topResult.OK || !methodResult.OK || !testResult.OK {
-		return nil
-	}
-	top := topResult.Value.(*Regexp)
-	method := methodResult.Value.(*Regexp)
-	test := testResult.Value.(*Regexp)
+	top := lspNamingTopRe
+	method := lspNamingMethodRe
+	test := lspNamingTestRe
 
 	path := TrimPrefix(uri, "file://")
 	dir := PathDir(path)