Auto merge of rust-lang#89101 - ehuss:compiletest-incremental-build, r=Mark-Simulacrum

Support incremental in compiletest for non-incremental modes.

This adds first-class support for using incremental builds in non-incremental-mode tests.  These tests previously manually passed `-C incremental=tmp/foo` which resulted in reusing the same tmp folder between runs.  This means that these tests could fail whenever the on-disk incremental format changed (such as when updating one's local source tree).  This changes it so that these tests can pass a `// incremental-build` header which instructs compiletest to create a set aside a dedicated incremental directory which will be cleared before the test starts to ensure it has a clean slate.

Author: bors

src/test/codegen-units/partitioning/extern-drop-glue.rs

@@ -1,9 +1,10 @@
 //
 
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
 // We specify opt-level=0 because `drop_in_place` is `Internal` when optimizing
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/extern-drop-glue
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 // compile-flags:-Zinline-in-all-cgus -Copt-level=0
 
 #![allow(dead_code)]

src/test/codegen-units/partitioning/extern-generic.rs

@@ -1,7 +1,8 @@
 //
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=eager -Cincremental=tmp/partitioning-tests/extern-generic -Zshare-generics=y
+// incremental
+// compile-flags:-Zprint-mono-items=eager -Zshare-generics=y
 
 #![allow(dead_code)]
 #![crate_type="lib"]

src/test/codegen-units/partitioning/incremental-merging.rs

@@ -1,6 +1,7 @@
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/incremental-merging
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 // compile-flags:-Ccodegen-units=3
 
 #![crate_type = "rlib"]

src/test/codegen-units/partitioning/inlining-from-extern-crate.rs

@@ -1,7 +1,8 @@
 //
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/inlining-from-extern-crate
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 // compile-flags:-Zinline-in-all-cgus
 
 #![crate_type="lib"]

src/test/codegen-units/partitioning/local-drop-glue.rs

@@ -1,8 +1,9 @@
 //
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
 // We specify opt-level=0 because `drop_in_place` is `Internal` when optimizing
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/local-drop-glue
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 // compile-flags:-Zinline-in-all-cgus -Copt-level=0
 
 #![allow(dead_code)]

src/test/codegen-units/partitioning/local-generic.rs

@@ -1,6 +1,7 @@
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=eager -Cincremental=tmp/partitioning-tests/local-generic
+// incremental
+// compile-flags:-Zprint-mono-items=eager
 
 #![allow(dead_code)]
 #![crate_type="lib"]

src/test/codegen-units/partitioning/local-inlining-but-not-all.rs

@@ -1,7 +1,8 @@
 //
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/local-inlining-but-not-all
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 // compile-flags:-Zinline-in-all-cgus=no
 
 #![allow(dead_code)]

src/test/codegen-units/partitioning/local-inlining.rs

@@ -1,7 +1,8 @@
 //
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/local-inlining
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 // compile-flags:-Zinline-in-all-cgus
 
 #![allow(dead_code)]

src/test/codegen-units/partitioning/local-transitive-inlining.rs

@@ -1,7 +1,8 @@
 //
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/local-transitive-inlining
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 // compile-flags:-Zinline-in-all-cgus
 
 #![allow(dead_code)]

src/test/codegen-units/partitioning/methods-are-with-self-type.rs

@@ -4,9 +4,10 @@
 // ignore-test
 
 //
-// We specify -C incremental here because we want to test the partitioning for
+// We specify incremental here because we want to test the partitioning for
 // incremental compilation
-// compile-flags:-Zprint-mono-items=lazy -Cincremental=tmp/partitioning-tests/methods-are-with-self-type
+// incremental
+// compile-flags:-Zprint-mono-items=lazy
 
 #![allow(dead_code)]
 #![feature(start)]