Rollup merge of #93850 - asquared31415:extern-static-size-ice, r=jackh726

Don't ICE when an extern static is too big for the current architecture

Fixes #93760

Emit an error instead of ICEing when an `extern` static's size overflows the allowed maximum for the target.

Changes the error message in the existing `delay_span_bug` call to the true layout error, first for debugging purposes, but opted to leave in to potentially assist future developers as it was being reached in unexpected ways already.

2 files changed, 63 insertions, 0 deletions

diff --git a/src/test/ui/extern/extern-static-size-overflow.rs b/src/test/ui/extern/extern-static-size-overflow.rs
new file mode 100644
index 00000000000..30a0c445466
--- /dev/null
+++ b/src/test/ui/extern/extern-static-size-overflow.rs
@@ -0,0 +1,43 @@
+#[repr(C)]
+struct ReallyBig {
+    _a: [u8; usize::MAX],
+}
+
+// The limit for "too big for the current architecture" is dependent on the target pointer size
+// however it's artifically limited on 64 bits
+// logic copied from rustc_target::abi::TargetDataLayout::obj_size_bound()
+const fn max_size() -> usize {
+    #[cfg(target_pointer_width = "16")]
+    {
+        1 << 15
+    }
+
+    #[cfg(target_pointer_width = "32")]
+    {
+        1 << 31
+    }
+
+    #[cfg(target_pointer_width = "64")]
+    {
+        1 << 47
+    }
+
+    #[cfg(not(any(
+        target_pointer_width = "16",
+        target_pointer_width = "32",
+        target_pointer_width = "64"
+    )))]
+    {
+        isize::MAX as usize
+    }
+}
+
+extern "C" {
+    static FOO: [u8; 1];
+    static BAR: [u8; max_size() - 1];
+    static BAZ: [u8; max_size()]; //~ ERROR extern static is too large
+    static UWU: [usize; usize::MAX]; //~ ERROR extern static is too large
+    static A: ReallyBig; //~ ERROR extern static is too large
+}
+
+fn main() {}
diff --git a/src/test/ui/extern/extern-static-size-overflow.stderr b/src/test/ui/extern/extern-static-size-overflow.stderr
new file mode 100644
index 00000000000..f5173feec75
--- /dev/null
+++ b/src/test/ui/extern/extern-static-size-overflow.stderr
@@ -0,0 +1,20 @@
+error: extern static is too large for the current architecture
+  --> $DIR/extern-static-size-overflow.rs:38:5
+   |
+LL |     static BAZ: [u8; max_size()];
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: extern static is too large for the current architecture
+  --> $DIR/extern-static-size-overflow.rs:39:5
+   |
+LL |     static UWU: [usize; usize::MAX];
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: extern static is too large for the current architecture
+  --> $DIR/extern-static-size-overflow.rs:40:5
+   |
+LL |     static A: ReallyBig;
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+