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Issue metadata

Status: Duplicate
Merged: issue 692601
Owner: ----
Closed: May 2017
Components:
EstimatedDays: ----
NextAction: ----
OS: All
Pri: 3
Type: Bug

Blocking:
issue 723856



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Recompilation should be noop after a noop "gn gen"

Project Member Reported by wychen@chromium.org, May 19 2017

Issue description

What steps will reproduce the problem?
(1) Build a target
(2) Run "gn gen" or touch <OUT_DIR>/build.ninja
(3) Build the target again

What is the expected result?
It should be noop for the second build.

What happens instead?
There are still actions.

This was discovered when investigating issue 723856.
 
Components: -Infra
Not an infra issue (removing component).
`gn gen` will change build.ninja if the command line args passed to gen change, because build.ninja records the command used to generate the files. 

For example `gn gen out/Release && gn gen --ide=json out/Release` will modify build.ninja, because the flags are changing.

However, `gn gen out/Release && gn gen out/Release` should not touch build.ninja; if that's happening, that's most likely a bug.

Comment 3 by wychen@chromium.org, May 23 2017

You are right. The case in https://codereview.chromium.org/2891363004/ is different because it gives --ide. This is tracking the later case.

Comment 4 by wychen@chromium.org, May 23 2017

Mergedinto: 692601
Status: Duplicate (was: Untriaged)

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