Move touch command into makefile.cargo

[mbrubeck]

Fixes #54, fixes servo/servo#8890.

r? @larsbergstrom or @metajack

[mbrubeck]

I worried in #54 that this change might cause spurious re-compiles, but in my testing it does not.

[mbrubeck]

…and the Travis build failed with aclocal-1.14: command not found. Great.

[mbrubeck]

I forgot to escape the braces in the makefile. When I fix it, the build succeeds but it does cause spurious rebuilds. So I'll need to make it smarter.

[mbrubeck]

Updated to fix the Makefile command and to ensure that the touch command runs only once. This will still cause one extra re-build in many cases, but the extra build is very fast because it doesn't actually re-compile Harfbuzz. (So the first cargo build causes a full compile; the second one causes a fast no-op build; and the third one correctly does nothing at all.)

I can't think of any way of totally eliminating the spurious re-build.

[metajack]

Have you tried just removing the generated files and running autogen as the first step?

[mbrubeck]

Have you tried just removing the generated files and running autogen as the first step?

That should work, though Harfbuzz’s autogen.sh depends on both autoconf and Ragel, which would add two new prerequisites to the Servo build. Installing Ragel would be an additional (but small) hassle for Windows users.

[mbrubeck]

Have you tried just removing the generated files and running autogen as the first step?

I implemented this, and it has the same problems as the current PR. autogen.sh touches several dozen files in the source directory, and the timestamps of these generated files cause Cargo to re-run the build script.

However, I found that adding an explicit exclude list to Cargo.toml fixes the problem of extra rebuilds. I've updated my original PR to add this. r? @metajack

(We could additionally remove all the generated files from the tree and run autogen.sh, but this requires a much larger exclude list and also adds new build dependencies, as mentioned above.)

[manfredbrandl]

@metajack is there still a problem with this PR?

[metajack]

@bors-servo r+

Thanks for dealing with this. autotools stuff is never fun.

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Reviewed 3 of 3 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from the review on Reviewable.io

[mbrubeck]

@bors-servo r=metajack

[bors-servo]

📌 Commit 331eddc has been approved by metajack

[bors-servo]

⌛ Testing commit 331eddc with merge d831bfe...

[bors-servo]

☀️ Test successful - travis