From e8eebc11116429494d732a67d7b4ad9e6fcac855 Mon Sep 17 00:00:00 2001 From: Alex Crichton Date: Thu, 8 Oct 2015 21:36:00 -0700 Subject: [PATCH] Fix spurious rebuilds of the script crate The script crate currently has a build script, and Cargo will consider all files in the script crate as inputs to the build script as it otherwise doesn't know [what the input files are][cargo-1162]. This means that if any file in the source tree of the script crate changes (or is created) then Cargo will think it needs to re-run the build script and rebuild the crate. [cargo-1162]: https://github.com/rust-lang/cargo/issues/1162 The build script of the script crate is invoking python, and consequently Python is generating some bytecode files in the source tree. On the second build of Servo, Cargo will see these new files, think that something has changed, and will re-run the build script of the script crate. This change passes the `-B` flag to python to avoid generating these bytecode files, which should avoid tampering with the source tree and appease Cargo by ensuring that it doesn't get rebuilt. --- As a helpful tip to if this comes up again, this was discovered by using the changes in rust-lang/cargo@c447e9d plus the change in rust-lang/cargo#2044. Once `RUST_LOG` was set to `cargo::ops::cargo_rustc::fingerprint=info`, the second run of `./mach build` printed out: ``` precalculated components have changed: 1444364448.000000000s (/build/servo/components/script/dom/bindings/codegen/parser/WebIDL.pyc) != 1444364235.000000000s (/build/servo/components/script/document_loader.rs) ``` Which should help easily diagnose these kinds of problems in the future! --- components/script/makefile.cargo | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/components/script/makefile.cargo b/components/script/makefile.cargo index a2c4a7f6254..5611b127c5a 100644 --- a/components/script/makefile.cargo +++ b/components/script/makefile.cargo @@ -3,7 +3,7 @@ rwildcard=$(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2) \ $(filter $(subst *,%,$2),$d)) -PYTHON = $(shell which python2.7 2>/dev/null || echo python) +PYTHON = $(shell which python2.7 2>/dev/null || echo python) -B BINDINGS_SRC = $(shell pwd)/dom/bindings/codegen WEBIDLS_SRC = $(shell pwd)/dom/webidls WEBIDLS = $(call rwildcard,$(WEBIDLS_SRC),*.webidl)