add proc_macro test

Author: J-ZhengLi

tests/ui/auxiliary/proc_macros.rs

@@ -9,6 +9,7 @@ use proc_macro::token_stream::IntoIter;
 use proc_macro::Delimiter::{self, Brace, Parenthesis};
 use proc_macro::Spacing::{self, Alone, Joint};
 use proc_macro::{Group, Ident, Literal, Punct, Span, TokenStream, TokenTree as TT};
+use syn::spanned::Spanned;
 
 type Result<T> = core::result::Result<T, TokenStream>;
 
@@ -82,6 +83,21 @@ pub fn external(input: TokenStream) -> TokenStream {
     }
 }
 
+/// Takes an array repeat expression (i.e. [0_u32; 100]), and double its allocation size.
+#[proc_macro]
+pub fn make_it_big(input: TokenStream) -> TokenStream {
+    let mut expr_repeat = syn::parse_macro_input!(input as syn::ExprRepeat);
+    let len_span = expr_repeat.len.span();
+    if let syn::Expr::Lit(expr_lit) = &mut *expr_repeat.len {
+        if let syn::Lit::Int(lit_int) = &expr_lit.lit {
+            let orig_val = lit_int.base10_parse::<usize>().expect("not a valid length parameter");
+            let new_val = orig_val.saturating_mul(10);
+            expr_lit.lit = syn::parse_quote_spanned!( len_span => #new_val);
+        }
+    }
+    quote::quote! {#expr_repeat}.into()
+}
+
 /// Copies all the tokens, replacing all their spans with the given span. Tokens can be escaped
 /// either by `#ident` or `#(tokens)`.
 fn write_with_span(s: Span, mut input: IntoIter, out: &mut TokenStream) -> Result<()> {

tests/ui/large_stack_arrays.rs

@@ -1,6 +1,9 @@
+//@aux-build:proc_macros.rs
 #![warn(clippy::large_stack_arrays)]
 #![allow(clippy::large_enum_variant)]
 
+extern crate proc_macros;
+
 #[derive(Clone, Copy)]
 struct S {
     pub data: [u64; 32],
@@ -88,4 +91,6 @@ fn issue_12586() {
     let y = dummy!(vec![dummy![x, x, x, x, x]]);
     let y = dummy![[x, x, x, x, x]];
     //~^ ERROR: allocating a local array larger than 512000 bytes
+    let y = proc_macros::make_it_big!([x; 1]);
+    //~^ ERROR: allocating a local array larger than 512000 bytes
 }

tests/ui/large_stack_arrays.stderr

@@ -1,5 +1,5 @@
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:29:14
+  --> tests/ui/large_stack_arrays.rs:32:14
    |
 LL |     let _x = [build(); 3];
    |              ^^^^^^^^^^^^
@@ -9,71 +9,71 @@ LL |     let _x = [build(); 3];
    = help: to override `-D warnings` add `#[allow(clippy::large_stack_arrays)]`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:32:14
+  --> tests/ui/large_stack_arrays.rs:35:14
    |
 LL |     let _y = [build(), build(), build()];
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![build(), build(), build()].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:38:9
+  --> tests/ui/large_stack_arrays.rs:41:9
    |
 LL |         [0u32; 20_000_000],
    |         ^^^^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![0u32; 20_000_000].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:40:9
+  --> tests/ui/large_stack_arrays.rs:43:9
    |
 LL |         [S { data: [0; 32] }; 5000],
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![S { data: [0; 32] }; 5000].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:42:9
+  --> tests/ui/large_stack_arrays.rs:45:9
    |
 LL |         [Some(""); 20_000_000],
    |         ^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![Some(""); 20_000_000].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:44:9
+  --> tests/ui/large_stack_arrays.rs:47:9
    |
 LL |         [E::T(0); 5000],
    |         ^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![E::T(0); 5000].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:46:9
+  --> tests/ui/large_stack_arrays.rs:49:9
    |
 LL |         [0u8; usize::MAX],
    |         ^^^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![0u8; usize::MAX].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:81:25
+  --> tests/ui/large_stack_arrays.rs:84:25
    |
 LL |     let y = vec![dummy![[x, x, x, x, x]]];
    |                         ^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![x, x, x, x, x].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:84:13
+  --> tests/ui/large_stack_arrays.rs:87:13
    |
 LL |     let y = [x, x, dummy!(x), x, x];
    |             ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![x, x, dummy!(x), x, x].into_boxed_slice()`
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:67:13
+  --> tests/ui/large_stack_arrays.rs:70:13
    |
 LL |             [$a, $b, $a, $b]
    |             ^^^^^^^^^^^^^^^^
@@ -84,12 +84,20 @@ LL |     let y = dummy![x => x];
    = note: this error originates in the macro `dummy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: allocating a local array larger than 512000 bytes
-  --> tests/ui/large_stack_arrays.rs:89:20
+  --> tests/ui/large_stack_arrays.rs:92:20
    |
 LL |     let y = dummy![[x, x, x, x, x]];
    |                    ^^^^^^^^^^^^^^^
    |
    = help: consider allocating on the heap with `vec![x, x, x, x, x].into_boxed_slice()`
 
-error: aborting due to 11 previous errors
+error: allocating a local array larger than 512000 bytes
+  --> tests/ui/large_stack_arrays.rs:94:39
+   |
+LL |     let y = proc_macros::make_it_big!([x; 1]);
+   |                                       ^^^^^^
+   |
+   = help: consider allocating on the heap with `vec![x; 1].into_boxed_slice()`
+
+error: aborting due to 12 previous errors