learning from a non-existent verse

Those of you who are learning daf yomi will have learnt (or be about to learn) the first daf of Eruvin today. On this daf, the gemara tries to find a source for the maximum height and width of a hechsher mavoi. At one point the gemara tries to learn from a verse, which Tosefot point out does not exist. Here is the Gemara (Eruvin 2a):

והכא היינו טעמא דרבי יהודה דכתיב אל פתח אולם הבית ורבנן אי הוה כתב אל פתח אולם כדקאמרת השתא דכתיב אל פתח אולם הבית הבית הפתוח לאולם

If you prefer I might say: According to R. Judah's view also the sanctity of the Hekal is distinct from that of the Ulam, but the reason for R. Judah's ruling here is because it is written: To the entrance of the Ulam of the house. And the
Rabbis? If it has been written: ‘To the entrance of the Ulam’ [the implication would indeed have been] as you suggested; now, however, that the text reads,I ‘To the entrance of the Ulam of the house’, [the meaning is the entrance of] the house that opens into the Ulam. But is not this text written in connection with the Tabernacle?

Tosefot write:

דכתיב אל פתח אולם הבית. זה הפסוק אינו בשום מקום ואור"י דמצינו דכתיב (יחזקאל מ) אולם הבית ובקרא אחרינא (שם מז) כתיב פתח הבית והוי כאלו נכתב בהדיא בחד קרא פתח אולם הבית וקאמרי רבנן אי כתב פתח אולם כדקאמרת פי' שלא היה כתוב בשום מקום אולם הבית:

"To the entrance of the Ulam of the house": This verse does not appear in any place. Rabbeinu Yitzchak says that we find that the verse states, "The Ulam of hte house" (Yechezkel 40) and in another verse it states, "Entrance of the house" (ibid. 47). The Gemara treats them as if they were written together in a single verse "The entrance the Ulam of the hosue." The Rabbis answer that if it would have said, "Entranceof the Ulam" it would be as you suggested. Meaning, since it does not state "Entrance of the Ulam" in any place.

If you look in Mahartz Chajes he points to another Tosefot later in the masechta (65a). Rashi suggests that another non-existent verse may in fact be from sefer Ben Sira (which is one of the books of the apocrypha, and according to Rabbi Akiva one loses one's Olam HaBa by reading it)! Tosefot then lists several other places where the Talmud cites verses from Ben Sira as if they are verses in Tanach.

בצר אל יורה. פירש בקונטרס בדקתי אחר מקרא זה ואינו בכל הכתובים ושמא בספר בן סירא הוא ומצינו בכמה מקומות שמביא הש"ס מקראות הכתובים בספר בן סירא

Rashi says that he has searched for this verse, but has not found it anywhere in Tanach. Perhaps it is from Sefer Ben Sira. We find many places that the Gemara cites verses written in Ben Sira.

Look at Tosefot there for other places where the Gemara quotes from Ben Sira as if it was quoting verse from Tanach.

(This post is partly a response to DovBear who claims that people never discuss what they have learnt in Daf Yomi. Well I'm discussing it now.)