fix(issue list): reject pull request-only search qualifiers

pkg/cmd/issue/list/http.go

@@ -2,6 +2,7 @@ package list
 
 import (
 	"fmt"
+	"regexp"
 
 	"github.com/cli/cli/v2/api"
 	fd "github.com/cli/cli/v2/internal/featuredetection"
@@ -9,6 +10,8 @@ import (
 	prShared "github.com/cli/cli/v2/pkg/cmd/pr/shared"
 )
 
+var pullRequestSearchQualifierRE = regexp.MustCompile(`(?i)\b(?:is|type):(?:pr|pull-?request)\b`)
+
 func listIssues(client *api.Client, repo ghrepo.Interface, filters prShared.FilterOptions, limit int) (*api.IssuesAndTotalCount, error) {
 	var states []string
 	switch filters.State {
@@ -114,6 +117,10 @@ loop:
 }
 
 func searchIssues(client *api.Client, detector fd.Detector, repo ghrepo.Interface, filters prShared.FilterOptions, limit int) (*api.IssuesAndTotalCount, error) {
+	if pullRequestSearchQualifierRE.MatchString(filters.Search) {
+		return nil, fmt.Errorf("cannot use pull request search qualifiers with `gh issue list`; use `gh pr list` instead")
+	}
+
 	// TODO advancedIssueSearchCleanup
 	// We won't need feature detection when GHES 3.17 support ends, since
 	// the advanced issue search is the only available search backend for

pkg/cmd/issue/list/http_test.go

@@ -214,3 +214,22 @@ func TestSearchIssuesAndAdvancedSearch(t *testing.T) {
 		})
 	}
 }
+
+func TestSearchIssues_rejectsPullRequestQualifiers(t *testing.T) {
+	reg := &httpmock.Registry{}
+	defer reg.Verify(t)
+
+	httpClient := &http.Client{Transport: reg}
+	client := api.NewClientFromHTTP(httpClient)
+
+	_, err := searchIssues(
+		client,
+		fd.AdvancedIssueSearchSupportedAsOnlyBackend(),
+		ghrepo.New("OWNER", "REPO"),
+		prShared.FilterOptions{Search: "is:pr"},
+		30,
+	)
+
+	assert.EqualError(t, err, "cannot use pull request search qualifiers with `gh issue list`; use `gh pr list` instead")
+	assert.Len(t, reg.Requests, 0)
+}