httpcaddyfile: fix incorrect error message on duplicate matchers (#7780)

Parse each matcher segment individually using NewDispenser(segment) instead
of DispenseDirective(dir), which coalesced all same-name segments into one
token stream. This caused the second definition name to be misinterpreted
as a matcher module name, producing 'module not registered: http.matchers.@name'
instead of the correct 'matcher is defined more than once' error.

By parsing segments individually, the existing duplicate check in
parseMatcherDefinitions naturally catches the duplicate on the second pass.

Signed-off-by: Brunotlps <brunoteixlps@gmail.com>

caddyconfig/httpcaddyfile/httptype.go

@@ -108,7 +108,7 @@ func (st ServerType) Setup(
 		matcherDefs := make(map[string]caddy.ModuleMap)
 		for _, segment := range sb.block.Segments {
 			if dir := segment.Directive(); strings.HasPrefix(dir, matcherPrefix) {
-				d := sb.block.DispenseDirective(dir)
+				d := caddyfile.NewDispenser(segment)
 				err := parseMatcherDefinitions(d, matcherDefs)
 				if err != nil {
 					return nil, warnings, err

caddyconfig/httpcaddyfile/httptype_test.go

@@ -2,6 +2,7 @@ package httpcaddyfile
 
 import (
 	"encoding/json"
+	"strings"
 	"testing"
 
 	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
@@ -10,8 +11,9 @@ import (
 
 func TestMatcherSyntax(t *testing.T) {
 	for i, tc := range []struct {
-		input       string
-		expectError bool
+		input          string
+		expectError    bool
+		expectContains string
 	}{
 		{
 			input: `http://localhost
@@ -53,6 +55,34 @@ func TestMatcherSyntax(t *testing.T) {
 			`,
 			expectError: false,
 		},
+		{
+			input: `http://localhost {
+				@test {
+					path /test
+				}
+				@test {
+					path /other
+				}
+				respond @test "hello"
+			}
+			`,
+			expectError:    true,
+			expectContains: "is defined more than once",
+		},
+		{
+			input: `(snippet) {
+				@{args[0]} {
+					path /{args[0]}
+				}
+				respond @{args[0]} "hello"
+			}
+			http://localhost {
+				import snippet foo
+				import snippet bar
+			}
+			`,
+			expectError: false,
+		},
 		{
 			input: `@matcher {
 				path /matcher-not-allowed/outside-of-site-block/*
@@ -73,6 +103,13 @@ func TestMatcherSyntax(t *testing.T) {
 			t.Errorf("Test %d error expectation failed Expected: %v, got %s", i, tc.expectError, err)
 			continue
 		}
+
+		if err != nil && tc.expectContains != "" {
+			if !strings.Contains(err.Error(), tc.expectContains) {
+				t.Errorf("Test %d error message mismatch: expected to contain %q, got %q",
+					i, tc.expectContains, err.Error())
+			}
+		}
 	}
 }