gccrs: Do proper const folding during typechecking for array capacities

This patch adds proper folding to the const expression for array capacity we
already have the const folding mechanics and the query system needed to handle cases
where the capacity is a function call in a const context. This leverages and pulls the
gcc tree capacity into the TyTy::ArrayType so it can be used for more typechecking and
eventually doing more const generics work.

Addresses Rust-GCC#3885
Fixes Rust-GCC#3882

gcc/rust/ChangeLog:

	* backend/rust-compile-base.cc (HIRCompileBase::query_compile_const_expr): new wrapper
	* backend/rust-compile-base.h: add prototype
	* backend/rust-compile-context.cc (Context::get): singleton helper
	* backend/rust-compile-context.h: likewise
	* backend/rust-compile-type.cc (TyTyResolveCompile::visit): handle infer's that can default
	* rust-session-manager.cc (Session::compile_crate): create the gcc context earlier for tychk
	* typecheck/rust-hir-type-check-base.cc (TypeCheckBase::resolve_literal): const fold it
	* typecheck/rust-hir-type-check-expr.cc (TypeCheckExpr::visit): likewise
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::visit): likewise
	* typecheck/rust-tyty.cc (BaseType::monomorphized_clone): fix constructor call
	(ArrayType::as_string): print capacity
	(ArrayType::clone): fix constructor call
	* typecheck/rust-tyty.h: track capacity
	* typecheck/rust-unify.cc (UnifyRules::expect_array): check the capacities

gcc/testsuite/ChangeLog:

	* rust/compile/all-cast.rs: shows array capacity now
	* rust/compile/arrays2.rs: likewise
	* rust/compile/const3.rs: fix error message
	* rust/compile/const_generics_3.rs: disable until typecheck we get proper errors now!
	* rust/compile/usize1.rs: proper capacity error message

Signed-off-by: Philip Herron <herron.philip@googlemail.com>

5 files changed, 5 insertions, 6 deletions

diff --git a/gcc/testsuite/rust/compile/all-cast.rs b/gcc/testsuite/rust/compile/all-cast.rs
index fa24373..6d8576c 100644
--- a/gcc/testsuite/rust/compile/all-cast.rs
+++ b/gcc/testsuite/rust/compile/all-cast.rs
@@ -4,7 +4,7 @@ fn main() {
 
     0u32 as char; // { dg-error "cannot cast .u32. as .char., only .u8. can be cast as .char." }
 
-    let x = &[1_usize, 2] as [usize]; // { dg-error "cast to unsized type: .& .usize:CAPACITY.. as ..usize.." }
+    let x = &[1_usize, 2] as [usize]; // { dg-error "cast to unsized type: .& .usize; 2.. as ..usize.." }
 
     let a = &0u8; // Here, `x` is a `&u8`.
     let y: u32 = a as u32; // { dg-error "casting .& u8. as .u32. is invalid" }
diff --git a/gcc/testsuite/rust/compile/arrays2.rs b/gcc/testsuite/rust/compile/arrays2.rs
index 668bcf0..1090059 100644
--- a/gcc/testsuite/rust/compile/arrays2.rs
+++ b/gcc/testsuite/rust/compile/arrays2.rs
@@ -1,5 +1,4 @@
-// { dg-additional-options "-w" }
 fn main() {
     let array: [i32; 5] = [1, 2, 3];
-    // { dg-error "mismatched types, expected an array with a fixed size of 5 elements, found one with 3 elements" "" { target *-*-* } .-1 }
+    // { dg-error "mismatched types, expected ..i32; 5.. but got ...integer.; 3.. .E0308." "" { target *-*-* } .-1 }
 }
diff --git a/gcc/testsuite/rust/compile/const3.rs b/gcc/testsuite/rust/compile/const3.rs
index 22dc3d3..c1d0f29 100644
--- a/gcc/testsuite/rust/compile/const3.rs
+++ b/gcc/testsuite/rust/compile/const3.rs
@@ -3,5 +3,5 @@ fn size() -> usize {
 }
 
 fn main() {
-    let a = [15; size()]; // { dg-error "only functions marked as .const. are allowed to be called from constant contexts" }
+    let a = [15; size()]; // { dg-error "calls in constants are limited to constant functions, tuple structs and tuple variants" }
 }
diff --git a/gcc/testsuite/rust/compile/const_generics_3.rs b/gcc/testsuite/rust/compile/const_generics_3.rs
index 09d5835..d8b2ddf 100644
--- a/gcc/testsuite/rust/compile/const_generics_3.rs
+++ b/gcc/testsuite/rust/compile/const_generics_3.rs
@@ -1,4 +1,4 @@
-// { dg-additional-options "-w -frust-compile-until=compilation" }
+// { dg-additional-options "-w -frust-compile-until=typecheck" }
 
 #[lang = "sized"]
 trait Sized {}
diff --git a/gcc/testsuite/rust/compile/usize1.rs b/gcc/testsuite/rust/compile/usize1.rs
index 36cb99b..08f6c9c 100644
--- a/gcc/testsuite/rust/compile/usize1.rs
+++ b/gcc/testsuite/rust/compile/usize1.rs
@@ -1,5 +1,5 @@
 fn main() {
     let a = [1, 2, 3];
     let b: u32 = 1;
-    let c = a[b]; // { dg-error "the type ...integer..CAPACITY.. cannot be indexed by .u32." }
+    let c = a[b]; // { dg-error "the type ...integer.; 3.. cannot be indexed by .u32." }
 }