使用git

Question

如果你有多个功能的docblocks，删除一个函数会创建一个次优补丁。

index.js：

/**
 * Function foo description.
 */
function foo() {}

/**
 * Function bar description.
 */
function bar() {}

使用docblock删除foo函数会生成以下补丁：

diff --git a/index.js b/index.js
index f4e18ef..933004f 100644
--- a/index.js
+++ b/index.js
@@ -1,9 +1,4 @@
 /**
- * Function foo description.
- */
-function foo() {}
-
-/**
  * Function bar description.
  */
 function bar() {}

这意味着任何带有它的合并提交触摸函数foo和函数栏之间的空间现在会导致冲突。 例如，假设我们在删除foo之前创建了一个分支feature-1，并在index.js中在两者之间添加了一个函数foobar。冲突如下：

/**
<<<<<<< HEAD
=======
 * Function foo description.
 */
function foo() {}

/**
 * Function foobar description.
 */
function foobar() {}

/**
>>>>>>> feature-1
 * Function bar description.
 */
function bar() {}

我想如果/**从顶部被抓住就不会有问题。我敢肯定，git更喜欢从最终删除，但我想强迫它从一开始就抓住它。有没有办法轻松做到这一点？或者只是手动修补编辑？

Answer 1

It's far from perfect, but the new --compaction-heuristic in Git 2.9 often does what you want. See this blog post for details. You can configure it to be on by default, but given that it sometimes makes things worse, I have not done so:

git config --global diff.compactionHeuristic true

Your Git version must be at least 2.9 for this to have any effect.

One flaw in the current implementation is that it quite literally requires a blank line above the modified section. Starting at the top of the file is not sufficient. For instance, suppose we start with:

block:
This file has
three blocks.

block:
There is a blank line
between each.

block:
This is the third
block.

If we delete the middle block, the default diff retains the second block: line and deletes the third block: line. Turning on compaction moves the diff hunk up until it reaches the blank line above the second block:, which is what we want.

Unfortunately, if we delete the first block, the compaction heuristic attempts to move the diff hunk up to include the first block: line, but fails because it hits the top of the file, where there is no blank line above it (as there is no line at all above it). It therefore leaves the first word block: in place and deletes the second.

(Fixing this would require only that the compaction algorithm provide a "virtual line zero" that is blank. Note that the problem itself never occurs at the end of the file since the default diff favors deletion of later lines. Meanwhile, an ugly workaround is to leave a blank line at the top of each file, just so that compaction can see it.)