Upgrade rust/crates/proc-macro-hack to 0.5.18 am: e23d8e27aa am: 11521d5d5d

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/proc-macro-hack/+/1372957

Change-Id: I2225ad0858e9b8005577c49541b2d4425ac47cb0

8 files changed, 127 insertions, 89 deletions

diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index e1a1090..24bc86c 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "35b1fa620a6486ed4b544d4fec6aa8cbdd017bd6"
+    "sha1": "3da1be8f9519c725b1f425a954b06a1a0a8b25ac"
   }
 }
diff --git a/.github/FUNDING.yml b/.github/FUNDING.yml
new file mode 100644
index 0000000..7507077
--- /dev/null
+++ b/.github/FUNDING.yml
@@ -0,0 +1 @@
+github: dtolnay
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fea412f..ca24eac 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,11 +12,13 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [nightly, beta, stable, 1.31.0]
+        rust: [nightly, beta, stable, 1.42.0, 1.31.0]
     steps:
       - uses: actions/checkout@v2
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
+      - if: matrix.rust == '1.31.0'
+        run: echo 'extern crate proc_macro;' >> demo-hack-impl/src/lib.rs
       - run: cargo run --manifest-path example/Cargo.toml
       - run: cargo test --all
diff --git a/Cargo.toml b/Cargo.toml
index 102757c..67fadfc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@
 [package]
 edition = "2018"
 name = "proc-macro-hack"
-version = "0.5.16"
+version = "0.5.18"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 description = "Procedural macros in expression position"
 readme = "README.md"
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index 1f75add..153d880 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -1,6 +1,6 @@
 [package]
 name = "proc-macro-hack"
-version = "0.5.16"
+version = "0.5.18"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
diff --git a/METADATA b/METADATA
index 932bd30..0fd8eb1 100644
--- a/METADATA
+++ b/METADATA
@@ -9,11 +9,11 @@ third_party {
     type: GIT
     value: "https://github.com/dtolnay/proc-macro-hack"
   }
-  version: "0.5.16"
+  version: "0.5.18"
   license_type: NOTICE
   last_upgrade_date {
     year: 2020
-    month: 5
-    day: 25
+    month: 7
+    day: 26
   }
 }
diff --git a/README.md b/README.md
index d6a6463..df7a2ec 100644
--- a/README.md
+++ b/README.md
@@ -6,14 +6,20 @@ Procedural macros in expression position
 [<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-proc--macro--hack-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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" height="20">](https://docs.rs/proc-macro-hack)
 [<img alt="build status" src="https://img.shields.io/github/workflow/status/dtolnay/proc-macro-hack/CI/master?style=for-the-badge" height="20">](https://github.com/dtolnay/proc-macro-hack/actions?query=branch%3Amaster)
 
-As of Rust 1.30, the language supports user-defined function-like procedural
-macros. However these can only be invoked in item position, not in
-statements or expressions.
+<table><tr><td><hr>
+<b>Note:</b> <i>As of Rust 1.45 this crate is superseded by native support for
+#[proc_macro] in expression position. Only consider using this crate if you care
+about supporting compilers between 1.31 and 1.45.</i>
+<hr></td></tr></table>
+
+Since Rust 1.30, the language supports user-defined function-like procedural
+macros. However these can only be invoked in item position, not in statements or
+expressions.
 
 This crate implements an alternative type of procedural macro that can be
 invoked in statement or expression position.
 
-This approach works with any stable or nightly Rust version 1.31+.
+This approach works with any Rust version 1.31+.
 
 ## Defining procedural macros
 
@@ -33,8 +39,6 @@ The function signature is the same as for ordinary function-like procedural
 macros.
 
 ```rust
-extern crate proc_macro;
-
 use proc_macro::TokenStream;
 use proc_macro_hack::proc_macro_hack;
 use quote::quote;
diff --git a/src/lib.rs b/src/lib.rs
index 16d7823..901a719 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,7 +6,13 @@
 //!
 //! <br>
 //!
-//! As of Rust 1.30, the language supports user-defined function-like procedural
+//! <table><tr><td><hr>
+//! <b>Note:</b> <i>As of Rust 1.45 this crate is superseded by native support
+//! for #[proc_macro] in expression position. Only consider using this crate if
+//! you care about supporting compilers between 1.31 and 1.45.</i>
+//! <hr></td></tr></table>
+//!
+//! Since Rust 1.30, the language supports user-defined function-like procedural
 //! macros. However these can only be invoked in item position, not in
 //! statements or expressions.
 //!
@@ -31,8 +37,8 @@
 //! macros.
 //!
 //! ```
-//! extern crate proc_macro;
-//!
+//! # extern crate proc_macro;
+//! #
 //! use proc_macro::TokenStream;
 //! use proc_macro_hack::proc_macro_hack;
 //! use quote::quote;
@@ -262,86 +268,111 @@ fn expand_export(export: Export, args: ExportArgs) -> TokenStream {
     };
 
     let from = export.from;
-    let rules = export
-        .macros
-        .into_iter()
-        .map(|Macro { name, export_as }| {
-            let actual_name = actual_proc_macro_name(&name);
-            let dispatch = dispatch_macro_name(&name);
-            let call_site = call_site_macro_name(&name);
-
-            let export_dispatch = if args.support_nested {
-                quote! {
-                    #[doc(hidden)]
-                    #vis use proc_macro_nested::dispatch as #dispatch;
-                }
-            } else {
-                quote!()
-            };
+    let mut actual_names = TokenStream::new();
+    let mut export_dispatch = TokenStream::new();
+    let mut export_call_site = TokenStream::new();
+    let mut macro_rules = TokenStream::new();
+    for Macro { name, export_as } in &export.macros {
+        let actual_name = actual_proc_macro_name(&name);
+        let dispatch = dispatch_macro_name(&name);
+        let call_site = call_site_macro_name(&name);
+
+        if !actual_names.is_empty() {
+            actual_names.extend(quote!(,));
+        }
+        actual_names.extend(quote!(#actual_name));
 
-            let proc_macro_call = if args.support_nested {
-                let extra_bangs = (0..args.internal_macro_calls)
-                    .map(|_| TokenTree::Punct(Punct::new('!', Spacing::Alone)))
-                    .collect::<TokenStream>();
-                quote! {
-                    #crate_prefix #dispatch! { ($($proc_macro)*) #extra_bangs }
-                }
-            } else {
-                quote! {
-                    proc_macro_call!()
-                }
-            };
+        if !export_dispatch.is_empty() {
+            export_dispatch.extend(quote!(,));
+        }
+        export_dispatch.extend(quote!(dispatch as #dispatch));
 
-            let export_call_site = if args.fake_call_site {
-                quote! {
-                    #[doc(hidden)]
-                    #vis use proc_macro_hack::fake_call_site as #call_site;
-                }
-            } else {
-                quote!()
-            };
+        if !export_call_site.is_empty() {
+            export_call_site.extend(quote!(,));
+        }
+        export_call_site.extend(quote!(fake_call_site as #call_site));
 
-            let do_derive = if !args.fake_call_site {
-                quote! {
-                    #[derive(#crate_prefix #actual_name)]
-                }
-            } else if crate_prefix.is_some() {
-                quote! {
-                    use #crate_prefix #actual_name;
-                    #[#crate_prefix #call_site ($($proc_macro)*)]
-                    #[derive(#actual_name)]
-                }
-            } else {
-                quote! {
-                    #[#call_site ($($proc_macro)*)]
-                    #[derive(#actual_name)]
-                }
-            };
+        let do_derive = if !args.fake_call_site {
+            quote! {
+                #[derive(#crate_prefix #actual_name)]
+            }
+        } else if crate_prefix.is_some() {
+            quote! {
+                use #crate_prefix #actual_name;
+                #[#crate_prefix #call_site ($($proc_macro)*)]
+                #[derive(#actual_name)]
+            }
+        } else {
+            quote! {
+                #[#call_site ($($proc_macro)*)]
+                #[derive(#actual_name)]
+            }
+        };
 
+        let proc_macro_call = if args.support_nested {
+            let extra_bangs = (0..args.internal_macro_calls)
+                .map(|_| TokenTree::Punct(Punct::new('!', Spacing::Alone)))
+                .collect::<TokenStream>();
             quote! {
-                #[doc(hidden)]
-                #vis use #from::#actual_name;
-
-                #export_dispatch
-                #export_call_site
-
-                #attrs
-                #macro_export
-                macro_rules! #export_as {
-                    ($($proc_macro:tt)*) => {{
-                        #do_derive
-                        #[allow(dead_code)]
-                        enum ProcMacroHack {
-                            #enum_variant = (stringify! { $($proc_macro)* }, 0).1,
-                        }
-                        #proc_macro_call
-                    }};
-                }
+                #crate_prefix #dispatch! { ($($proc_macro)*) #extra_bangs }
+            }
+        } else {
+            quote! {
+                proc_macro_call!()
             }
-        })
-        .collect();
+        };
+
+        macro_rules.extend(quote! {
+            #attrs
+            #macro_export
+            macro_rules! #export_as {
+                ($($proc_macro:tt)*) => {{
+                    #do_derive
+                    #[allow(dead_code)]
+                    enum ProcMacroHack {
+                        #enum_variant = (stringify! { $($proc_macro)* }, 0).1,
+                    }
+                    #proc_macro_call
+                }};
+            }
+        });
+    }
+
+    if export.macros.len() != 1 {
+        export_dispatch = quote!({#export_dispatch});
+        export_call_site = quote!({#export_call_site});
+        actual_names = quote!({#actual_names});
+    }
+
+    let export_dispatch = if args.support_nested {
+        quote! {
+            #[doc(hidden)]
+            #vis use proc_macro_nested::#export_dispatch;
+        }
+    } else {
+        quote!()
+    };
+
+    let export_call_site = if args.fake_call_site {
+        quote! {
+            #[doc(hidden)]
+            #vis use proc_macro_hack::#export_call_site;
+        }
+    } else {
+        quote!()
+    };
+
+    let expanded = quote! {
+        #[doc(hidden)]
+        #vis use #from::#actual_names;
+
+        #export_dispatch
+        #export_call_site
+
+        #macro_rules
+    };
 
-    wrap_in_enum_hack(dummy, rules)
+    wrap_in_enum_hack(dummy, expanded)
 }
 
 fn expand_define(define: Define) -> TokenStream {