feat(lint): lint PL/pgSQL function and DO bodies, report body syntax errors

pkg/lint/lint_test.go

@@ -123,3 +123,34 @@ func TestCustomEngine(t *testing.T) {
 	}
 	_ = diags
 }
+
+func TestPlpgsqlBodyLint(t *testing.T) {
+	src := "create function f() returns void language plpgsql as $$\nbegin\n  perform 1;\n  select * from t;\nend;\n$$;\n" +
+		"create function g() returns void language plpgsql as $$\nbegin\n  selec 1;\nend;\n$$;\n" +
+		"create function p() returns void language plpython3u as $$\nselect * from nothing\n$$;\n" +
+		"do $$ begin select * from t; end $$;\n"
+	diags, err := lint.New().Check(src, "x.sql")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var cor001, pl []diagnostics.Diagnostic
+	for _, d := range diags {
+		switch d.RuleID {
+		case "COR001":
+			cor001 = append(cor001, d)
+		case "PLPGSQL":
+			pl = append(pl, d)
+		}
+	}
+	if len(cor001) != 2 || cor001[0].Line != 4 || cor001[0].Col != 10 || cor001[1].Line != 15 {
+		t.Errorf("COR001 in bodies: %+v", cor001)
+	}
+	for _, d := range cor001 {
+		if d.Fix != nil {
+			t.Errorf("embedded diagnostic must not carry fixes: %+v", d)
+		}
+	}
+	if len(pl) != 1 || pl[0].Line != 9 || pl[0].Col != 3 {
+		t.Errorf("PLPGSQL syntax error: %+v", pl)
+	}
+}