govet: add httpmux analyzer (#5717)

Author: alexandear

.golangci.next.reference.yml

@@ -1587,6 +1587,8 @@ linters:
         - findcall
         # Report assembly that clobbers the frame pointer before saving it.
         - framepointer
+        # Report using Go 1.22 enhanced ServeMux patterns in older Go versions.
+        - httpmux
         # Check for mistakes using HTTP responses.
         - httpresponse
         # Detect impossible interface-to-interface type assertions.
@@ -1668,6 +1670,7 @@ linters:
         - fieldalignment
         - findcall
         - framepointer
+        - httpmux
         - httpresponse
         - ifaceassert
         - loopclosure

pkg/golinters/govet/govet.go

@@ -24,6 +24,7 @@ import (
 	"golang.org/x/tools/go/analysis/passes/fieldalignment"
 	"golang.org/x/tools/go/analysis/passes/findcall"
 	"golang.org/x/tools/go/analysis/passes/framepointer"
+	"golang.org/x/tools/go/analysis/passes/httpmux"
 	"golang.org/x/tools/go/analysis/passes/httpresponse"
 	"golang.org/x/tools/go/analysis/passes/ifaceassert"
 	_ "golang.org/x/tools/go/analysis/passes/inspect" // unused internal analyzer
@@ -77,6 +78,7 @@ var (
 		fieldalignment.Analyzer,
 		findcall.Analyzer,
 		framepointer.Analyzer,
+		httpmux.Analyzer,
 		httpresponse.Analyzer,
 		ifaceassert.Analyzer,
 		loopclosure.Analyzer,