Rollup merge of rust-lang#61231 - pnkfelix:issue-59548-linkage-diagnostic, r=petrochenkov

Fix linkage diagnostic so it doesn't ICE for external crates

Fix linkage diagnostic so it doesn't ICE for external crates

(As a drive-by improvement, improved the diagnostic to indicate *why* `*const T` or `*mut T` is required.)

Fix rust-lang#59548
Fix rust-lang#61232

Author: Centril

src/librustc_codegen_llvm/consts.rs

@@ -102,7 +102,7 @@ fn check_and_apply_linkage(
     attrs: &CodegenFnAttrs,
     ty: Ty<'tcx>,
     sym: LocalInternedString,
-    span: Option<Span>
+    span: Span
 ) -> &'ll Value {
     let llty = cx.layout_of(ty).llvm_type(cx);
     if let Some(linkage) = attrs.linkage {
@@ -116,11 +116,8 @@ fn check_and_apply_linkage(
         let llty2 = if let ty::RawPtr(ref mt) = ty.sty {
             cx.layout_of(mt.ty).llvm_type(cx)
         } else {
-            if let Some(span) = span {
-                cx.sess().span_fatal(span, "must have type `*const T` or `*mut T`")
-            } else {
-                bug!("must have type `*const T` or `*mut T`")
-            }
+            cx.sess().span_fatal(
+                span, "must have type `*const T` or `*mut T` due to `#[linkage]` attribute")
         };
         unsafe {
             // Declare a symbol `foo` with the desired linkage.
@@ -136,14 +133,7 @@ fn check_and_apply_linkage(
             let mut real_name = "_rust_extern_with_linkage_".to_string();
             real_name.push_str(&sym);
             let g2 = cx.define_global(&real_name, llty).unwrap_or_else(||{
-                if let Some(span) = span {
-                    cx.sess().span_fatal(
-                        span,
-                        &format!("symbol `{}` is already defined", &sym)
-                    )
-                } else {
-                    bug!("symbol `{}` is already defined", &sym)
-                }
+                cx.sess().span_fatal(span, &format!("symbol `{}` is already defined", &sym))
             });
             llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage);
             llvm::LLVMSetInitializer(g2, g1);
@@ -240,7 +230,7 @@ impl CodegenCx<'ll, 'tcx> {
                     ref attrs, span, node: hir::ForeignItemKind::Static(..), ..
                 }) => {
                     let fn_attrs = self.tcx.codegen_fn_attrs(def_id);
-                    (check_and_apply_linkage(&self, &fn_attrs, ty, sym, Some(span)), attrs)
+                    (check_and_apply_linkage(&self, &fn_attrs, ty, sym, span), attrs)
                 }
 
                 item => bug!("get_static: expected static, found {:?}", item)
@@ -260,7 +250,8 @@ impl CodegenCx<'ll, 'tcx> {
             debug!("get_static: sym={} item_attr={:?}", sym, self.tcx.item_attrs(def_id));
 
             let attrs = self.tcx.codegen_fn_attrs(def_id);
-            let g = check_and_apply_linkage(&self, &attrs, ty, sym, None);
+            let span = self.tcx.def_span(def_id);
+            let g = check_and_apply_linkage(&self, &attrs, ty, sym, span);
 
             // Thread-local statics in some other crate need to *always* be linked
             // against in a thread-local fashion, so we need to be sure to apply the

src/test/ui/linkage-attr/auxiliary/def_colliding_external.rs

@@ -0,0 +1,7 @@
+#![feature(linkage)]
+#![crate_type = "lib"]
+
+extern {
+    #[linkage="external"]
+    pub static collision: *const i32;
+}

src/test/ui/linkage-attr/auxiliary/def_illtyped_external.rs

@@ -0,0 +1,5 @@
+#![feature(linkage)]
+#![crate_type = "lib"]
+
+#[linkage="external"]
+pub static EXTERN: u32 = 0;

src/test/ui/linkage-attr/linkage-detect-extern-generated-name-collision.rs

@@ -0,0 +1,21 @@
+// rust-lang/rust#61232: We used to ICE when trying to detect a
+// collision on the symbol generated for the external linkage item in
+// an extern crate.
+
+// aux-build:def_colliding_external.rs
+
+extern crate def_colliding_external as dep1;
+
+#[no_mangle]
+pub static _rust_extern_with_linkage_collision: i32 = 0;
+
+mod dep2 {
+    #[no_mangle]
+    pub static collision: usize = 0;
+}
+
+fn main() {
+    unsafe {
+       println!("{:p}", &dep1::collision);
+    }
+}

src/test/ui/linkage-attr/linkage-detect-extern-generated-name-collision.stderr

@@ -0,0 +1,8 @@
+error: symbol `collision` is already defined
+  --> $DIR/auxiliary/def_colliding_external.rs:6:5
+   |
+LL |     pub static collision: *const i32;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/linkage-attr/linkage-detect-local-generated-name-collision.rs

@@ -0,0 +1,23 @@
+#![feature(linkage)]
+
+mod dep1 {
+    extern {
+        #[linkage="external"]
+        #[no_mangle]
+        pub static collision: *const i32; //~ ERROR symbol `collision` is already defined
+    }
+}
+
+#[no_mangle]
+pub static _rust_extern_with_linkage_collision: i32 = 0;
+
+mod dep2 {
+    #[no_mangle]
+    pub static collision: usize = 0;
+}
+
+fn main() {
+    unsafe {
+       println!("{:p}", &dep1::collision);
+    }
+}

src/test/ui/linkage-attr/linkage-detect-local-generated-name-collision.stderr

@@ -0,0 +1,8 @@
+error: symbol `collision` is already defined
+  --> $DIR/linkage-detect-local-generated-name-collision.rs:7:9
+   |
+LL |         pub static collision: *const i32;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/linkage-attr/linkage-requires-raw-ptr.rs

@@ -0,0 +1,10 @@
+// rust-lang/rust#59548: We used to ICE when trying to use a static
+// with a type that violated its own `#[linkage]`.
+
+// aux-build:def_illtyped_external.rs
+
+extern crate def_illtyped_external as dep;
+
+fn main() {
+    println!("{:p}", &dep::EXTERN);
+}

src/test/ui/linkage-attr/linkage-requires-raw-ptr.stderr

@@ -0,0 +1,8 @@
+error: must have type `*const T` or `*mut T` due to `#[linkage]` attribute
+  --> $DIR/auxiliary/def_illtyped_external.rs:5:1
+   |
+LL | pub static EXTERN: u32 = 0;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/linkage2.rs src/test/ui/linkage-attr/linkage2.rs

@@ -7,7 +7,7 @@
 
 extern {
     #[linkage = "extern_weak"] static foo: i32;
-    //~^ ERROR: must have type `*const T` or `*mut T`
+    //~^ ERROR: must have type `*const T` or `*mut T` due to `#[linkage]` attribute
 }
 
 fn main() {

src/test/ui/linkage2.stderr src/test/ui/linkage-attr/linkage2.stderr

@@ -1,4 +1,4 @@
-error: must have type `*const T` or `*mut T`
+error: must have type `*const T` or `*mut T` due to `#[linkage]` attribute
   --> $DIR/linkage2.rs:9:32
    |
 LL |     #[linkage = "extern_weak"] static foo: i32;