Merge commit '93f0a9a91f58c9b2153868f458402155fb6265bb' into clippy-s…

…ubtree-update

src/tools/clippy/.github/driver.sh

@@ -50,11 +50,11 @@ diff -u normalized.stderr tests/ui/double_neg.stderr
 
 # make sure "clippy-driver --rustc --arg" and "rustc --arg" behave the same
 SYSROOT=$(rustc --print sysroot)
-diff -u <(LD_LIBRARY_PATH=${SYSROOT}/lib ./target/debug/clippy-driver --rustc --version --verbose) <(rustc --version --verbose)
+diff -u <(./target/debug/clippy-driver --rustc --version --verbose) <(rustc --version --verbose)
 
 echo "fn main() {}" >target/driver_test.rs
 # we can't run 2 rustcs on the same file at the same time
-CLIPPY=$(LD_LIBRARY_PATH=${SYSROOT}/lib ./target/debug/clippy-driver ./target/driver_test.rs --rustc)
+CLIPPY=$(./target/debug/clippy-driver ./target/driver_test.rs --rustc)
 RUSTC=$(rustc ./target/driver_test.rs)
 diff -u <($CLIPPY) <($RUSTC)
 

src/tools/clippy/.github/workflows/clippy.yml

@@ -44,11 +44,6 @@ jobs:
       run: rustup show active-toolchain
 
     # Run
-    - name: Set LD_LIBRARY_PATH (Linux)
-      run: |
-        SYSROOT=$(rustc --print sysroot)
-        echo "LD_LIBRARY_PATH=${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}" >> $GITHUB_ENV
-
     - name: Build
       run: cargo build --tests --features deny-warnings,internal
 
@@ -72,6 +67,6 @@ jobs:
       working-directory: clippy_dev
 
     - name: Test clippy-driver
-      run: bash .github/driver.sh
-      env:
-        OS: ${{ runner.os }}
+      run: |
+        TOOLCHAIN=$(rustup show active-toolchain | cut -f1 -d' ')
+        rustup run $TOOLCHAIN bash .github/driver.sh

src/tools/clippy/.github/workflows/clippy_bors.yml

@@ -59,7 +59,7 @@ jobs:
           host: i686-unknown-linux-gnu
         - os: windows-latest
           host: x86_64-pc-windows-msvc
-        - os: macos-latest
+        - os: macos-13
           host: x86_64-apple-darwin
 
     runs-on: ${{ matrix.os }}
@@ -87,23 +87,6 @@ jobs:
         rustup show active-toolchain
 
     # Run
-    - name: Set LD_LIBRARY_PATH (Linux)
-      if: runner.os == 'Linux'
-      run: |
-        SYSROOT=$(rustc --print sysroot)
-        echo "LD_LIBRARY_PATH=${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}" >> $GITHUB_ENV
-    - name: Link rustc dylib (MacOS)
-      if: runner.os == 'macOS'
-      run: |
-        SYSROOT=$(rustc --print sysroot)
-        sudo mkdir -p /usr/local/lib
-        sudo find "${SYSROOT}/lib" -maxdepth 1 -name '*dylib' -exec ln -s {} /usr/local/lib \;
-    - name: Set PATH (Windows)
-      if: runner.os == 'Windows'
-      run: |
-        SYSROOT=$(rustc --print sysroot)
-        echo "$SYSROOT/bin" >> $GITHUB_PATH
-
     - name: Build
       run: cargo build --tests --features deny-warnings,internal
 
@@ -136,7 +119,9 @@ jobs:
       working-directory: clippy_dev
 
     - name: Test clippy-driver
-      run: bash .github/driver.sh
+      run: |
+        TOOLCHAIN=$(rustup show active-toolchain | cut -f1 -d' ')
+        rustup run $TOOLCHAIN bash .github/driver.sh
       env:
         OS: ${{ runner.os }}
 
@@ -236,11 +221,6 @@ jobs:
     - name: Install toolchain
       run: rustup show active-toolchain
 
-    - name: Set LD_LIBRARY_PATH
-      run: |
-        SYSROOT=$(rustc --print sysroot)
-        echo "LD_LIBRARY_PATH=${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}" >> $GITHUB_ENV
-
     # Download
     - name: Download target dir
       uses: actions/download-artifact@v3
@@ -254,8 +234,8 @@ jobs:
     # Run
     - name: Test ${{ matrix.integration }}
       run: |
-        RUSTUP_TOOLCHAIN="$(rustup show active-toolchain | grep -o -E "nightly-[0-9]{4}-[0-9]{2}-[0-9]{2}")" \
-          $CARGO_TARGET_DIR/debug/integration --show-output
+          TOOLCHAIN=$(rustup show active-toolchain | cut -f1 -d' ')
+          rustup run $TOOLCHAIN $CARGO_TARGET_DIR/debug/integration --show-output
       env:
         INTEGRATION: ${{ matrix.integration }}
 

src/tools/clippy/book/src/development/trait_checking.md

@@ -94,6 +94,53 @@ impl LateLintPass<'_> for CheckTokioAsyncReadExtTrait {
 }
 ```
 
+## Creating Types Programmatically
+
+Traits are often generic over a type parameter, e.g. `Borrow<T>` is generic
+over `T`. Rust allows us to implement a trait for a specific type. For example,
+we can implement `Borrow<[u8]>` for a hypothetical type `Foo`. Let's suppose
+that we would like to find whether our type actually implements `Borrow<[u8]>`.
+
+To do so, we can use the same `implements_trait` function as above, and supply
+a type parameter that represents `[u8]`. Since `[u8]` is a specialization of
+`[T]`, we can use the  [`Ty::new_slice`][new_slice] method to create a type
+that represents `[T]` and supply `u8` as a type parameter.
+To create a `ty::Ty` programmatically, we rely on `Ty::new_*` methods. These
+methods create a `TyKind` and then wrap it in a `Ty` struct. This means we
+have access to all the primitive types, such as `Ty::new_char`,
+`Ty::new_bool`, `Ty::new_int`, etc. We can also create more complex types,
+such as slices, tuples, and references out of these basic building blocks.
+
+For trait checking, it is not enough to create the types, we need to convert
+them into [GenericArg]. In rustc, a generic is an entity that the compiler
+understands and has three kinds, type, const and lifetime. By calling
+`.into()` on a constructed [Ty], we wrap the type into a generic which can
+then be used by the query system to decide whether the specialized trait
+is implemented.
+
+The following code demonstrates how to do this:
+
+```rust
+
+use rustc_middle::ty::Ty;
+use clippy_utils::ty::implements_trait;
+use rustc_span::symbol::sym;
+
+let ty = todo!("Get the `Foo` type to check for a trait implementation");
+let borrow_id = cx.tcx.get_diagnostic_item(sym::Borrow).unwrap(); // avoid unwrap in real code
+let slice_of_bytes_t = Ty::new_slice(cx.tcx, cx.tcx.types.u8);
+let generic_param = slice_of_bytes_t.into();
+if implements_trait(cx, ty, borrow_id, &[generic_param]) {
+    todo!("Rest of lint implementation")
+}
+```
+
+In essence, the [Ty] struct allows us to create types programmatically in a
+representation that can be used by the compiler and the query engine. We then
+use the `rustc_middle::Ty` of the type we are interested in, and query the
+compiler to see if it indeed implements the trait we are interested in.
+
+
 [DefId]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir/def_id/struct.DefId.html
 [diagnostic_items]: https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-items.html
 [lang_items]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir/lang_items/struct.LanguageItems.html
@@ -102,4 +149,7 @@ impl LateLintPass<'_> for CheckTokioAsyncReadExtTrait {
 [symbol]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/symbol/struct.Symbol.html
 [symbol_index]: https://doc.rust-lang.org/beta/nightly-rustc/rustc_span/symbol/sym/index.html
 [TyCtxt]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/context/struct.TyCtxt.html
+[Ty]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Ty.html
 [rust]: https://github.com/rust-lang/rust
+[new_slice]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Ty.html#method.new_slice
+[GenericArg]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.GenericArg.html

src/tools/clippy/book/src/development/type_checking.md

@@ -123,6 +123,22 @@ the [`TypeckResults::node_type()`][node_type] method inside of bodies.
 
 > **Warning**: Don't use `hir_ty_to_ty` inside of bodies, because this can cause ICEs.
 
+## Creating Types programmatically
+
+A common usecase for creating types programmatically is when we want to check if a type implements a trait (see
+[Trait Checking](trait_checking.md)).
+
+Here's an example of how to create a `Ty` for a slice of `u8`, i.e. `[u8]`
+
+```rust
+use rustc_middle::ty::Ty;
+// assume we have access to a LateContext
+let ty = Ty::new_slice(cx.tcx, Ty::new_u8());
+```
+
+In general, we rely on `Ty::new_*` methods. These methods define the basic building-blocks that the
+type-system and trait-system use to define and understand the written code.
+
 ## Useful Links
 
 Below are some useful links to further explore the concepts covered