Auto merge of #45867 - michaelwoerister:check-ich-stability, r=nikomatsakis

incr.comp.: Verify stability of incr. comp. hashes and clean up various other things.

The main contribution of this PR is that it adds the `-Z incremental-verify-ich` functionality. Normally, when the red-green tracking system determines that a certain query result has not changed, it does not re-compute the incr. comp. hash (ICH) for that query result because that hash is already known. `-Z incremental-verify-ich` tells the compiler to re-hash the query result and compare the new hash against the cached hash. This is a rather thorough way of
- testing hashing implementation stability,
- finding missing `[input]` annotations on `DepNodes`, and
- finding missing read-edges,

since both a missed read and a missing `[input]` annotation can lead to something being marked as green instead of red and thus will have a different hash than it should have.

Case in point, implementing this verification logic and activating it for all `src/test/incremental` tests has revealed several such oversights, all of which are fixed in this PR.

r? @nikomatsakis

src/test/incremental/hashes/panic_exprs.rs

@@ -152,13 +152,48 @@ pub fn mod_by_zero(val: i32) -> i32 {
 }
 
 
+// shift left ------------------------------------------------------------------
+#[cfg(cfail1)]
+pub fn shift_left(val: i32, shift: usize) -> i32 {
+    val << shift
+}
+
+#[cfg(not(cfail1))]
+#[rustc_clean(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_dirty(label="HirBody", cfg="cfail2")]
+#[rustc_clean(label="HirBody", cfg="cfail3")]
+#[rustc_metadata_clean(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+pub fn shift_left(val: i32, shift: usize) -> i32 {
+    val << shift
+}
+
+
+// shift right ------------------------------------------------------------------
+#[cfg(cfail1)]
+pub fn shift_right(val: i32, shift: usize) -> i32 {
+    val >> shift
+}
+
+#[cfg(not(cfail1))]
+#[rustc_clean(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_dirty(label="HirBody", cfg="cfail2")]
+#[rustc_clean(label="HirBody", cfg="cfail3")]
+#[rustc_metadata_clean(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+pub fn shift_right(val: i32, shift: usize) -> i32 {
+    val >> shift
+}
+
 
 // THE FOLLOWING ITEMS SHOULD NOT BE INFLUENCED BY THEIR SOURCE LOCATION
 
 // bitwise ---------------------------------------------------------------------
 #[cfg(cfail1)]
 pub fn bitwise(val: i32) -> i32 {
-    !val & 0x101010101 | 0x45689 ^ 0x2372382 << 1 >> 1
+    !val & 0x101010101 | 0x45689 ^ 0x2372382
 }
 
 #[cfg(not(cfail1))]
@@ -169,7 +204,7 @@ pub fn bitwise(val: i32) -> i32 {
 #[rustc_metadata_clean(cfg="cfail2")]
 #[rustc_metadata_clean(cfg="cfail3")]
 pub fn bitwise(val: i32) -> i32 {
-    !val & 0x101010101 | 0x45689 ^ 0x2372382 << 1 >> 1
+    !val & 0x101010101 | 0x45689 ^ 0x2372382
 }
 
 

src/test/incremental/ich_nested_items.rs

@@ -11,29 +11,29 @@
 // Check that the hash of `foo` doesn't change just because we ordered
 // the nested items (or even added new ones).
 
-// revisions: rpass1 rpass2
+// revisions: cfail1 cfail2
+// must-compile-successfully
 
+#![crate_type = "rlib"]
 #![feature(rustc_attrs)]
 
-#[cfg(rpass1)]
-fn foo() {
-    fn bar() { }
-    fn baz() { }
+#[cfg(cfail1)]
+pub fn foo() {
+    pub fn bar() { }
+    pub fn baz() { }
 }
 
-#[cfg(rpass2)]
-#[rustc_clean(label="Hir", cfg="rpass2")]
-#[rustc_clean(label="HirBody", cfg="rpass2")]
-fn foo() {
-    #[rustc_clean(label="Hir", cfg="rpass2")]
-    #[rustc_clean(label="HirBody", cfg="rpass2")]
-    fn baz() { } // order is different...
+#[cfg(cfail2)]
+#[rustc_clean(label="Hir", cfg="cfail2")]
+#[rustc_dirty(label="HirBody", cfg="cfail2")]
+pub fn foo() {
+    #[rustc_clean(label="Hir", cfg="cfail2")]
+    #[rustc_clean(label="HirBody", cfg="cfail2")]
+    pub fn baz() { } // order is different...
 
-    #[rustc_clean(label="Hir", cfg="rpass2")]
-    #[rustc_clean(label="HirBody", cfg="rpass2")]
-    fn bar() { } // but that doesn't matter.
+    #[rustc_clean(label="Hir", cfg="cfail2")]
+    #[rustc_clean(label="HirBody", cfg="cfail2")]
+    pub fn bar() { } // but that doesn't matter.
 
-    fn bap() { } // neither does adding a new item
+    pub fn bap() { } // neither does adding a new item
 }
-
-fn main() { }

src/test/incremental/remove_source_file/main.rs

@@ -11,21 +11,24 @@
 // This test case makes sure that the compiler doesn't crash due to a failing
 // table lookup when a source file is removed.
 
-// revisions:rpass1 rpass2
+// revisions:cfail1 cfail2
 
 // Note that we specify -g so that the FileMaps actually get referenced by the
 // incr. comp. cache:
 // compile-flags: -Z query-dep-graph -g
+// must-compile-successfully
 
-#[cfg(rpass1)]
+#![crate_type= "rlib"]
+
+#[cfg(cfail1)]
 mod auxiliary;
 
-#[cfg(rpass1)]
-fn main() {
+#[cfg(cfail1)]
+pub fn foo() {
     auxiliary::print_hello();
 }
 
-#[cfg(rpass2)]
-fn main() {
+#[cfg(cfail2)]
+pub fn foo() {
     println!("hello");
 }

src/test/incremental/spans_in_type_debuginfo.rs

@@ -14,7 +14,6 @@
 // revisions:rpass1 rpass2
 // compile-flags: -Z query-dep-graph -g
 
-#![rustc_partition_reused(module="spans_in_type_debuginfo", cfg="rpass2")]
 #![rustc_partition_reused(module="spans_in_type_debuginfo-structs", cfg="rpass2")]
 #![rustc_partition_reused(module="spans_in_type_debuginfo-enums", cfg="rpass2")]