| 1 | -*- text -*- |
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| 2 | |
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| 3 | TREE CONFLICTS USE CASES AND DESIRED BEHAVIOURS |
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| 4 | |
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| 5 | |
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| 6 | Issue reference: http://subversion.tigris.org/issues/show_bug.cgi?id=2282 |
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| 7 | |
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| 8 | (These use cases are based on a scenario paper "SVN move/rename |
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| 9 | problems & suggested improvements" submitted by a corporate Subversion |
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| 10 | user, which may be found attached to issue #2282.) |
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| 11 | |
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| 12 | -------------------------------------------------------------------------- |
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| 13 | |
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| 14 | ========== |
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| 15 | USE CASE 1 |
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| 16 | ========== |
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| 17 | |
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| 18 | Description |
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| 19 | |
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| 20 | During an update, a file modification is merged onto a file move. |
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| 21 | |
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| 22 | Current Behavior |
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| 23 | |
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| 24 | Developer A modifies Foo.c and commits it to the repository. |
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| 25 | |
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| 26 | Developer B has simultaneously moved Foo.c to Bar.c in his working |
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| 27 | copy. |
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| 28 | |
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| 29 | B cannot commit because the working copy is out of date, so B runs 'svn |
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| 30 | update'. The update will apply A's modifications to Foo.c in the |
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| 31 | repository to Foo.c in B's working copy. |
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| 32 | |
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| 33 | Problems With Current Behavior |
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| 34 | |
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| 35 | First problem: |
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| 36 | |
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| 37 | A's modification of Foo.c will effectively be reverted by B's new |
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| 38 | revision. Foo.c will be deleted in the new revision, and Bar.c will be |
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| 39 | added with the content of the original Foo.c before A's modifications. |
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| 40 | Hence A will likely get angry with B. |
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| 41 | |
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| 42 | Second problem: |
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| 43 | |
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| 44 | B is not explicitly warned about reverting A's modification of Foo.c. |
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| 45 | The only visible warning is that Foo.c is left behind unversioned in |
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| 46 | B's working copy because it has "local" modifications (which were in |
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| 47 | fact made by A). This will likely escape B's attention. |
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| 48 | |
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| 49 | Diagram of current behavior |
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| 50 | |
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| 51 | |
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| 52 | (edit) |
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| 53 | wcA -- Foo.c' -------> |
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| 54 | / | |
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| 55 | / |commit |
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| 56 | repos / v |
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| 57 | -- Foo.c -------------- Foo.c' --------------- Bar.c ---> |
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| 58 | \ | ^ |
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| 59 | \ |update |commit |
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| 60 | \ v | |
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| 61 | wcB -- +Bar.c ---------- +Bar.c ---- Bar.c ---> |
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| 62 | (move) -Foo.c -Foo.c' ?Foo.c' (unversioned) |
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| 63 | |
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| 64 | |
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| 65 | Desired behavior |
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| 66 | |
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| 67 | When user B updates, A's modifications to Foo.c should be merged into |
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| 68 | Bar.c. Signal a text conflict if necessary. |
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| 69 | |
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| 70 | Foo.c should be deleted from B's working copy. |
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| 71 | |
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| 72 | A tree conflict should be signalled to inform B of the new changes |
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| 73 | to Bar.c, so that B can review the modified Bar.c before committing it. |
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| 74 | |
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| 75 | Diagram of desired behaviour |
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| 76 | |
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| 77 | |
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| 78 | (edit) |
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| 79 | wcA -- Foo.c' -------> |
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| 80 | / | |
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| 81 | / |commit |
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| 82 | repos / v |
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| 83 | -- Foo.c --------------- Foo.c' ------------------------ Bar.c' ---> |
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| 84 | \ | ^ ^ |
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| 85 | \ |update |commit |commit |
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| 86 | \ v |(fails) | |
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| 87 | wcB -- +Bar.c ------------ +Bar.c' --------------> |
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| 88 | (move) -Foo.c -Foo.c ^ |
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| 89 | | |
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| 90 | resolved |
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| 91 | |
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| 92 | |
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| 93 | ========== |
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| 94 | USE CASE 2 |
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| 95 | ========== |
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| 96 | |
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| 97 | Description |
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| 98 | |
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| 99 | During an update, a file move is merged onto a file modification. |
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| 100 | |
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| 101 | This is essentially the same as Use Case 1, with the difference that |
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| 102 | this time, B does the edit and A does the move. |
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| 103 | |
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| 104 | Current Behavior |
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| 105 | |
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| 106 | Developer B modifies Foo.c in his working copy. |
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| 107 | |
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| 108 | Developer A has simultaneously moved Foo.c to Bar.c and commits |
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| 109 | the move to the repository. |
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| 110 | |
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| 111 | B cannot commit because his working copy is out of date, so B runs |
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| 112 | 'svn update'. The next update will add Bar.c (with the same content |
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| 113 | as the original Foo.c) to B's working copy, and delete Foo.c from |
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| 114 | B's working copy. Since B made local modifications to Foo.c, |
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| 115 | it will not be deleted from disk but left behind unversioned. |
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| 116 | |
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| 117 | Problems with Current Behavior |
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| 118 | |
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| 119 | Developer B may not notice that Foo.c fell out of version control. |
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| 120 | B's source tree in the working copy likely builds fine because Foo.c |
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| 121 | is still present on disk. So B may commit an incomplete change set, |
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| 122 | possibly breaking the tree. Everybody will get angry with B if this |
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| 123 | happens. |
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| 124 | |
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| 125 | Diagram of Current Behaviour |
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| 126 | |
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| 127 | |
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| 128 | (move) |
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| 129 | wcA -- +Bar.c -------> |
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| 130 | / -Foo.c | |
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| 131 | / |commit |
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| 132 | repos / v |
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| 133 | -- Foo.c --------------- Bar.c -----------------------> |
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| 134 | \ | ^ |
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| 135 | \ |update |commit |
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| 136 | \ v |(no-op) |
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| 137 | wcB -- Foo.c' ------------ Bar.c -------> |
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| 138 | (edit) ?Foo.c' (unversioned) |
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| 139 | |
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| 140 | |
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| 141 | Desired Behavior |
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| 142 | |
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| 143 | In B's working copy, the update should add Bar.c and merge the local |
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| 144 | modifications to Foo.c into Bar.c. Signal a text conflict if necessary. |
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| 145 | |
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| 146 | Foo.c should be deleted from B's working copy. |
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| 147 | |
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| 148 | A tree conflict should be signaled to inform B that Foo.c has been |
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| 149 | renamed to Bar.c |
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| 150 | |
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| 151 | Diagram of Desired Behaviour |
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| 152 | |
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| 153 | |
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| 154 | (move) |
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| 155 | wcA -- +Bar.c -------> |
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| 156 | / -Foo.c | |
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| 157 | / |commit |
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| 158 | repos / v |
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| 159 | -- Foo.c --------------- Bar.c -------------------------- Bar.c'---> |
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| 160 | \ | ^ ^ |
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| 161 | \ |update |commit |commit |
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| 162 | \ v |(fails) | |
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| 163 | wcB -- Foo.c' ------------+Bar.c' ------------------------> |
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| 164 | (edit) -Foo.c' ^ |
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| 165 | | |
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| 166 | resolved |
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| 167 | |
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| 168 | |
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| 169 | ========== |
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| 170 | USE CASE 3 |
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| 171 | ========== |
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| 172 | |
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| 173 | Description |
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| 174 | |
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| 175 | During an update, a file move is merged onto a conflicting file move. |
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| 176 | |
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| 177 | Current Behavior |
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| 178 | |
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| 179 | Developer A moves Foo.c to Bar.c and commits the move to the repository. |
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| 180 | |
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| 181 | Developer B has moved Foo.c to Bix.c in his working copy. |
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| 182 | |
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| 183 | B cannot commit because his working copy is out of date, so B runs |
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| 184 | 'svn update'. The update will add Bar.c to B's working copy and |
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| 185 | delete Foo.c from B's working copy (the latter is a no-op). |
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| 186 | |
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| 187 | Problems with Current Behavior |
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| 188 | |
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| 189 | After B's next commit, the content of the original Foo.c |
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| 190 | will exist twice in the source tree under two different paths, |
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| 191 | namely Bar.c and Bix.c, respectively. |
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| 192 | |
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| 193 | This may not have been intended. |
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| 194 | |
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| 195 | Diagram of Current Behavior |
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| 196 | |
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| 197 | |
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| 198 | (move) |
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| 199 | wcA -- +Bar.c ------> |
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| 200 | / -Foo.c | |
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| 201 | / |commit |
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| 202 | archive / v |
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| 203 | -- Foo.c --------------- Bar.c ------------------ Bar.c ---> |
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| 204 | \ | ^ Bix.c |
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| 205 | \ |update |commit |
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| 206 | \ v | |
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| 207 | wcB -- +Bix.c ---------- +Bix.c -------> |
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| 208 | (move) -Foo.c Bar.c |
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| 209 | |
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| 210 | |
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| 211 | Desired Behavior |
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| 212 | |
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| 213 | A tree conflict should be signaled to inform B of the conflicting rename |
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| 214 | operation. B can now decide on deleting either file or committing both. |
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| 215 | |
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| 216 | Diagram of Desired Behavior |
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| 217 | |
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| 218 | |
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| 219 | (move) |
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| 220 | wcA -- +Bar.c ------> |
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| 221 | / -Foo.c | |
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| 222 | / |commit |
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| 223 | archive / v |
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| 224 | -- Foo.c --------------- Bar.c -------------------------- Bar.c --> |
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| 225 | \ | ^ ^ (or Bix.c, |
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| 226 | \ |update |commit |commit or both) |
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| 227 | \ v |(fails) | |
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| 228 | wcB -- +Bix.c ---------- +Bix.c --------------> |
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| 229 | (move) -Foo.c Bar.c ^ |
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| 230 | | |
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| 231 | resolved |
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| 232 | |
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| 233 | |
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| 234 | ========== |
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| 235 | USE CASE 4 |
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| 236 | ========== |
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| 237 | |
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| 238 | Description |
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| 239 | |
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| 240 | A file modification is merged onto the source of a file move. |
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| 241 | |
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| 242 | Current Behavior |
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| 243 | |
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| 244 | Developer A modifies Foo.c and commits it to the repository. |
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| 245 | |
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| 246 | Developer B moves Foo.c to Bar.c and commits it to the repository. |
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| 247 | |
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| 248 | Developer merges A's new revision into his working copy. The merge |
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| 249 | will apply A's modification to Foo.c to the Foo.c in B's working |
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| 250 | copy. |
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| 251 | |
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| 252 | Problems With Current Behavior |
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| 253 | |
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| 254 | First problem: |
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| 255 | |
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| 256 | A's modification of Foo.c will not be merged to B's line of |
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| 257 | development because the merge skips the absent file. |
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| 258 | |
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| 259 | Second problem: |
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| 260 | |
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| 261 | B is not explicitly warned about reverting A's modification of Foo.c, |
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| 262 | except for a "skipped" warning in the output of the merge command, |
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| 263 | which might not be noticed. |
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| 264 | |
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| 265 | Diagram of current behavior |
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| 266 | |
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| 267 | |
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| 268 | (edit) |
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| 269 | urlA -- Foo.c' ------------------> |
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| 270 | / (r50) | |
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| 271 | / | |
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| 272 | -- Foo.c - |merge -c50 |
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| 273 | \ |(Foo.c skipped) |
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| 274 | \ | |
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| 275 | urlB -- +Bar.c ------------|-----------------> |
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| 276 | (move) -Foo.c \ | ^ |
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| 277 | \ | |commit |
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| 278 | \ v |(no-op) |
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| 279 | wcB -- Bar.c -- Bar.c ------ --> |
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| 280 | |
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| 281 | |
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| 282 | Desired behavior |
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| 283 | |
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| 284 | When user B merges, A's modifications to Foo.c should be merged into |
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| 285 | Bar.c. Signal a text conflict if necessary. |
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| 286 | |
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| 287 | A tree conflict should be signalled to inform B of the new changes |
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| 288 | to Bar.c, so that B can review the modified Bar.c before committing it. |
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| 289 | |
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| 290 | Diagram of desired behaviour |
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| 291 | |
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| 292 | |
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| 293 | (edit) |
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| 294 | urlA -- Foo.c' ------------------> |
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| 295 | / (r50) | |
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| 296 | / | |
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| 297 | -- Foo.c - |merge -c50 |
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| 298 | \ |(tree conflict) |
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| 299 | \ | |
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| 300 | urlB -- +Bar.c -------------|-------------------- Bar.c' --> |
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| 301 | (move) -Foo.c \ | ^ ^ |
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| 302 | \ | |commit |commit |
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| 303 | \ v |(fails) | |
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| 304 | wcB -- Bar.c -- Bar.c' ---------------> |
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| 305 | ^ |
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| 306 | | |
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| 307 | resolved |
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| 308 | |
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| 309 | |
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| 310 | ========== |
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| 311 | USE CASE 5 |
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| 312 | ========== |
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| 313 | |
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| 314 | Description |
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| 315 | |
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| 316 | A file move is merged onto a modification of the move-source. |
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| 317 | |
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| 318 | This is essentially the same as Use Case 4, with the difference that |
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| 319 | this time, B does the edit and A does the move. |
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| 320 | |
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| 321 | Current Behavior |
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| 322 | |
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| 323 | Developer A moves Foo.c to Bar.c and commits it to the repository. |
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| 324 | |
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| 325 | Developer B modifies Foo.cand commits it to the repository. |
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| 326 | |
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| 327 | Developer merges A's new revision into his working copy. The merge |
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| 328 | will add Bar.c (with the same content as the original Foo.c) and |
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| 329 | will delete B's Foo.c. |
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| 330 | |
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| 331 | Problems With Current Behavior |
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| 332 | |
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| 333 | First problem: |
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| 334 | |
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| 335 | B's has modified Foo.c in the past. This modification will be lost |
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| 336 | unless B reviews the history of Foo.c and Bar.c at both URLs and |
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| 337 | corrects the problem (e.g., via 'svn copy'). |
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| 338 | |
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| 339 | Diagram of current behavior |
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| 340 | |
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| 341 | |
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| 342 | (move) |
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| 343 | urlA -- +Bar.c -------------------> |
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| 344 | / -Foo.c | |
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| 345 | / (r50) | |
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| 346 | -- Foo.c - |merge -c50 |
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| 347 | \ | |
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| 348 | \ | |
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| 349 | urlB -- Foo.c' -------------|------------ Bar.c ---> |
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| 350 | (edit) \ | ^ |
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| 351 | \ | |commit |
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| 352 | \ v | |
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| 353 | wcB -- Foo.c' -- +Bar.c ------> |
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| 354 | -Foo.c' |
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| 355 | |
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| 356 | |
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| 357 | Desired behavior |
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| 358 | |
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| 359 | In B's working copy, the update should add Bar.c and merge the local |
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| 360 | modifications to Foo.c into Bar.c. Signal a text conflict if necessary. |
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| 361 | |
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| 362 | Foo.c should be deleted from B's working copy. |
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| 363 | |
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| 364 | A tree conflict should be signaled to inform B that Foo.c has been |
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| 365 | renamed to Bar.c |
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| 366 | |
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| 367 | Diagram of desired behaviour |
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| 368 | |
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| 369 | |
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| 370 | (move) |
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| 371 | urlA -- +Bar.c -------------------> |
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| 372 | / -Foo.c | |
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| 373 | / (r50) | |
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| 374 | -- Foo.c - |merge -c50 |
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| 375 | \ |(tree conflict) |
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| 376 | \ | |
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| 377 | urlB -- Foo.c' -------------|-------------------- Bar.c'--> |
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| 378 | (edit) \ | ^ ^ |
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| 379 | \ | |commit |commit |
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| 380 | \ v |(fails) | |
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| 381 | wcB -- Foo.c' -- Bar.c' ---------------> |
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| 382 | -Foo.c' ^ |
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| 383 | | |
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| 384 | resolved |
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| 385 | |
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| 386 | |
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| 387 | ========== |
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| 388 | USE CASE 6 |
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| 389 | ========== |
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| 390 | |
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| 391 | Description |
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| 392 | |
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| 393 | A file move is merged onto a conflicting file move. |
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| 394 | |
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| 395 | Current Behavior |
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| 396 | |
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| 397 | Developer A moves Foo.c to Bar.c and commits it to the repository. |
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| 398 | |
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| 399 | Developer B moves Foo.c to Bix.c and commits it to the repository. |
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| 400 | |
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| 401 | Developer merges A's new revision into his working copy. The merge |
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| 402 | will add Bar.c with history in B's working copy. |
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| 403 | |
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| 404 | Problems With Current Behavior |
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| 405 | |
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| 406 | After B's next commit, the content of the original Foo.c will exist |
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| 407 | twice in the source tree under two different paths (Bar.c and |
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| 408 | Bix.c). This may not have been intended. |
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| 409 | |
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| 410 | Diagram of current behavior |
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| 411 | |
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| 412 | |
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| 413 | (move) |
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| 414 | urlA -- +Bar.c ------------------> |
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| 415 | / -Foo.c | |
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| 416 | / (r50) | |
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| 417 | -- Foo.c - |merge -c50 |
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| 418 | \ | |
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| 419 | \ | |
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| 420 | urlB -- +Bix.c ------------|---------------- Bix.c ---> |
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| 421 | (move) -Foo.c \ | ^ Bar.c |
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| 422 | \ | |commit |
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| 423 | \ v | |
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| 424 | wcB -- Bix.c -- Bix.c ----------> |
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| 425 | +Bar.c |
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| 426 | |
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| 427 | |
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| 428 | Desired behavior |
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| 429 | |
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| 430 | A tree conflict should be signaled to inform B of the conflicting |
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| 431 | rename operation. B can delete either file or commit both. |
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| 432 | |
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| 433 | Diagram of desired behaviour |
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| 434 | |
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| 435 | |
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| 436 | (move) |
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| 437 | urlA -- +Bar.c -----------------> |
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| 438 | / -Foo.c | |
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| 439 | / (r50) | |
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| 440 | -- Foo.c - |merge -c50 |
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| 441 | \ |(tree conflict) |
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| 442 | \ | |
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| 443 | urlB -- +Bix.c ------------|------------------------- Bar.c --> |
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| 444 | (move) -Foo.c \ | ^ ^ (or Bix.c, |
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| 445 | \ | |commit |commit or both) |
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| 446 | \ v |(fails) | |
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| 447 | wcB -- Bix.c -- Bix.c --------------> |
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| 448 | +Bar.c ^ |
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| 449 | | |
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| 450 | resolved |
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| 451 | |
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