commit.cocci: refactor code, avoid double rewrite
"maybe" pointer in 'struct commit' is tricky because it can be lazily initialized to take advantage of commit-graph if available. This makes it not safe to access directly. This leads to a rule in commit.cocci to rewrite 'x->maybe_tree' to 'get_commit_tree(x)'. But that rule alone could lead to incorrectly rewrite assignments, e.g. from x->maybe_tree = yes to get_commit_tree(x) = yes Because of this we have a second rule to revert this effect. Szeder found out that we could do better by performing the assignment rewrite rule first, then the remaining is read-only access and handled by the current first rule. For this to work, we need to transform "x->maybe_tree = y" to something that does NOT contain "x->maybe_tree" to avoid the original first rule. This is where set_commit_tree() comes in. Helped-by: SZEDER Gábor <szeder.dev@gmail.com> Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Junio C Hamano

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@ -10,19 +10,25 @@ expression c;
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- c->maybe_tree->object.oid.hash
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+ get_commit_tree_oid(c)->hash
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// These excluded functions must access c->maybe_tree direcly.
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@@
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identifier f !~ "^(get_commit_tree|get_commit_tree_in_graph_one|load_tree_for_commit)$";
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identifier f !~ "^set_commit_tree$";
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expression c;
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expression s;
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@@
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f(...) {<...
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- c->maybe_tree = s
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+ set_commit_tree(c, s)
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...>}
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// These excluded functions must access c->maybe_tree direcly.
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// Note that if c->maybe_tree is written somewhere outside of these
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// functions, then the recommended transformation will be bogus with
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// get_commit_tree() on the LHS.
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@@
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identifier f !~ "^(get_commit_tree|get_commit_tree_in_graph_one|load_tree_for_commit|set_commit_tree)$";
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expression c;
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@@
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f(...) {<...
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- c->maybe_tree
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+ get_commit_tree(c)
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...>}
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@@
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expression c;
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expression s;
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@@
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- get_commit_tree(c) = s
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+ c->maybe_tree = s
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