Auto merge of #51369 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 7 pull requests

Successful merges:

 - #50852 (Add doc comment to hiding portions of code example)
 - #51183 (Update rustdoc book to suggest using Termination trait instead of hidden ‘foo’ function)
 - #51255 (Fix confusing error message for sub_instant)
 - #51256 (Fix crate-name option in rustdoc)
 - #51308 (Check array indices in constant propagation)
 - #51343 (test: Ignore some problematic tests on sparc and sparc64)
 - #51358 (Tests that #39963 is fixed on MIR borrowck)

Failed merges:

Author: bors

src/doc/rustdoc/src/documentation-tests.md

@@ -79,15 +79,17 @@ from your example, but are important to make the tests work. Consider
 an example block that looks like this:
 
 ```text
-/// Some documentation.
-# fn foo() {}
+/// /// Some documentation.
+/// # fn foo() {} // this function will be hidden
+/// println!("Hello, World!");
 ```
 
 It will render like this:
 
 ```rust
 /// Some documentation.
 # fn foo() {}
+println!("Hello, World!");
 ```
 
 Yes, that's right: you can add lines that start with `# `, and they will
@@ -168,37 +170,56 @@ By repeating all parts of the example, you can ensure that your example still
 compiles, while only showing the parts that are relevant to that part of your
 explanation.
 
-Another case where the use of `#` is handy is when you want to ignore
-error handling. Lets say you want the following,
+
+## Using `?` in doc tests
+
+When writing an example, it is rarely useful to include a complete error
+handling, as it would add significant amounts of boilerplate code. Instead, you
+may want the following:
 
 ```ignore
+/// ```
 /// use std::io;
 /// let mut input = String::new();
 /// io::stdin().read_line(&mut input)?;
+/// ```
 ```
 
-The problem is that `?` returns a `Result<T, E>` and test functions
-don't return anything so this will give a mismatched types error.
+The problem is that `?` returns a `Result<T, E>` and test functions don't
+return anything, so this will give a mismatched types error.
+
+You can get around this limitation by manually adding a `main` that returns
+`Result<T, E>`, because `Result<T, E>` implements the `Termination` trait:
 
 ```ignore
 /// A doc test using ?
 ///
 /// ```
 /// use std::io;
-/// # fn foo() -> io::Result<()> {
+///
+/// fn main() -> io::Result<()> {
+///     let mut input = String::new();
+///     io::stdin().read_line(&mut input)?;
+///     Ok(())
+/// }
+/// ```
+```
+
+Together with the `# ` from the section above, you arrive at a solution that
+appears to the reader as the initial idea but works with doc tests:
+
+```ignore
+/// ```
+/// use std::io;
+/// # fn main() -> io::Result<()> {
 /// let mut input = String::new();
 /// io::stdin().read_line(&mut input)?;
 /// # Ok(())
 /// # }
 /// ```
-# fn foo() {}
 ```
 
-You can get around this by wrapping the code in a function. This catches
-and swallows the `Result<T, E>` when running tests on the docs. This
-pattern appears regularly in the standard library.
-
-### Documenting macros
+## Documenting macros
 
 Here’s an example of documenting a macro:
 

src/librustc_mir/transform/const_prop.rs

@@ -240,16 +240,6 @@ impl<'b, 'a, 'tcx:'b> ConstPropagator<'b, 'a, 'tcx> {
     ) -> Option<Const<'tcx>> {
         let span = source_info.span;
         match *rvalue {
-            // No need to overwrite an already evaluated constant
-            Rvalue::Use(Operand::Constant(box Constant {
-                literal: Literal::Value {
-                    value: &ty::Const {
-                        val: ConstVal::Value(_),
-                        ..
-                    },
-                },
-                ..
-            })) => None,
             // This branch exists for the sanity type check
             Rvalue::Use(Operand::Constant(ref c)) => {
                 assert_eq!(c.ty, place_ty);

src/librustdoc/core.rs

@@ -230,7 +230,10 @@ pub fn run_core(search_paths: SearchPaths,
 
         let krate = panictry!(driver::phase_1_parse_input(control, &sess, &input));
 
-        let name = ::rustc_codegen_utils::link::find_crate_name(Some(&sess), &krate.attrs, &input);
+        let name = match crate_name {
+            Some(ref crate_name) => crate_name.clone(),
+            None => ::rustc_codegen_utils::link::find_crate_name(Some(&sess), &krate.attrs, &input),
+        };
 
         let mut crate_loader = CrateLoader::new(&sess, &cstore, &name);
 

src/libstd/sys/redox/time.rs

@@ -144,7 +144,7 @@ impl Instant {
 
     pub fn sub_instant(&self, other: &Instant) -> Duration {
         self.t.sub_timespec(&other.t).unwrap_or_else(|_| {
-            panic!("other was less than the current instant")
+            panic!("specified instant was later than self")
         })
     }
 

src/libstd/sys/unix/time.rs

@@ -289,7 +289,7 @@ mod inner {
 
         pub fn sub_instant(&self, other: &Instant) -> Duration {
             self.t.sub_timespec(&other.t).unwrap_or_else(|_| {
-                panic!("other was less than the current instant")
+                panic!("specified instant was later than self")
             })
         }
 

src/test/codegen/abi-main-signature-16bit-c-int.rs

@@ -22,6 +22,7 @@
 // ignore-powerpc64
 // ignore-s390x
 // ignore-sparc
+// ignore-sparc64
 // ignore-wasm32
 // ignore-x86
 // ignore-x86_64

src/test/codegen/fastcall-inreg.rs

@@ -29,6 +29,7 @@
 // ignore-r600
 // ignore-amdgcn
 // ignore-sparc
+// ignore-sparc64
 // ignore-sparcv9
 // ignore-sparcel
 // ignore-s390x

src/test/codegen/repr-transparent-aggregates-2.rs

@@ -14,6 +14,8 @@
 // ignore-asmjs
 // ignore-mips64
 // ignore-s390x
+// ignore-sparc
+// ignore-sparc64
 // ignore-wasm
 // ignore-x86
 // ignore-x86_64

src/test/codegen/stack-probes.rs

@@ -14,6 +14,8 @@
 // ignore-mips64
 // ignore-powerpc
 // ignore-s390x
+// ignore-sparc
+// ignore-sparc64
 // ignore-wasm
 // ignore-emscripten
 // ignore-windows

src/test/codegen/x86_mmx.rs

@@ -13,6 +13,8 @@
 // ignore-emscripten
 // ignore-mips
 // ignore-mips64
+// ignore-sparc
+// ignore-sparc64
 // compile-flags: -O
 
 #![feature(repr_simd)]