Auto merge of #97086 - 5225225:link-section-is-unsafe, r=davidtwco

Report unsafe for overriding link sections

I'm not too sure about the lint wording here, but I couldn't think of anything better.

compiler/rustc_lint/src/builtin.rs

@@ -338,6 +338,17 @@ impl UnsafeCode {
                 .emit();
         })
     }
+
+    fn report_overridden_symbol_section(&self, cx: &EarlyContext<'_>, span: Span, msg: &str) {
+        self.report_unsafe(cx, span, |lint| {
+            lint.build(msg)
+                .note(
+                    "the program's behavior with overridden link sections on items is unpredictable \
+                    and Rust cannot provide guarantees when you manually override them",
+                )
+                .emit();
+        })
+    }
 }
 
 impl EarlyLintPass for UnsafeCode {
@@ -385,6 +396,7 @@ impl EarlyLintPass for UnsafeCode {
                         "declaration of a `no_mangle` function",
                     );
                 }
+
                 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
                     self.report_overridden_symbol_name(
                         cx,
@@ -392,6 +404,14 @@ impl EarlyLintPass for UnsafeCode {
                         "declaration of a function with `export_name`",
                     );
                 }
+
+                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
+                    self.report_overridden_symbol_section(
+                        cx,
+                        attr.span,
+                        "declaration of a function with `link_section`",
+                    );
+                }
             }
 
             ast::ItemKind::Static(..) => {
@@ -402,6 +422,7 @@ impl EarlyLintPass for UnsafeCode {
                         "declaration of a `no_mangle` static",
                     );
                 }
+
                 if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
                     self.report_overridden_symbol_name(
                         cx,
@@ -409,6 +430,14 @@ impl EarlyLintPass for UnsafeCode {
                         "declaration of a static with `export_name`",
                     );
                 }
+
+                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
+                    self.report_overridden_symbol_section(
+                        cx,
+                        attr.span,
+                        "declaration of a static with `link_section`",
+                    );
+                }
             }
 
             _ => {}

src/test/ui/lint/lint-unsafe-code.rs

@@ -48,6 +48,9 @@ impl AssocFnTrait for AssocFnFoo {
 #[export_name = "bar"] fn bar() {} //~ ERROR: declaration of a function with `export_name`
 #[export_name = "BAR"] static BAR: u32 = 5; //~ ERROR: declaration of a static with `export_name`
 
+#[link_section = ".example_section"] fn uwu() {} //~ ERROR: declaration of a function with `link_section`
+#[link_section = ".example_section"] static UWU: u32 = 5; //~ ERROR: declaration of a static with `link_section`
+
 struct AssocFnBar;
 
 impl AssocFnBar {

src/test/ui/lint/lint-unsafe-code.stderr

@@ -51,8 +51,24 @@ LL | #[export_name = "BAR"] static BAR: u32 = 5;
    |
    = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
 
+error: declaration of a function with `link_section`
+  --> $DIR/lint-unsafe-code.rs:51:1
+   |
+LL | #[link_section = ".example_section"] fn uwu() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the program's behavior with overridden link sections on items is unpredictable and Rust cannot provide guarantees when you manually override them
+
+error: declaration of a static with `link_section`
+  --> $DIR/lint-unsafe-code.rs:52:1
+   |
+LL | #[link_section = ".example_section"] static UWU: u32 = 5;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the program's behavior with overridden link sections on items is unpredictable and Rust cannot provide guarantees when you manually override them
+
 error: declaration of a method with `export_name`
-  --> $DIR/lint-unsafe-code.rs:54:5
+  --> $DIR/lint-unsafe-code.rs:57:5
    |
 LL |     #[export_name = "bar"] fn bar() {}
    |     ^^^^^^^^^^^^^^^^^^^^^^
@@ -60,7 +76,7 @@ LL |     #[export_name = "bar"] fn bar() {}
    = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
 
 error: declaration of a method with `export_name`
-  --> $DIR/lint-unsafe-code.rs:58:5
+  --> $DIR/lint-unsafe-code.rs:61:5
    |
 LL |     #[export_name = "bar"] fn foo() {}
    |     ^^^^^^^^^^^^^^^^^^^^^^
@@ -68,79 +84,79 @@ LL |     #[export_name = "bar"] fn foo() {}
    = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
 
 error: declaration of an `unsafe` function
-  --> $DIR/lint-unsafe-code.rs:61:1
+  --> $DIR/lint-unsafe-code.rs:64:1
    |
 LL | unsafe fn baz() {}
    | ^^^^^^^^^^^^^^^^^^
 
 error: declaration of an `unsafe` trait
-  --> $DIR/lint-unsafe-code.rs:62:1
+  --> $DIR/lint-unsafe-code.rs:65:1
    |
 LL | unsafe trait Foo {}
    | ^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` trait
-  --> $DIR/lint-unsafe-code.rs:63:1
+  --> $DIR/lint-unsafe-code.rs:66:1
    |
 LL | unsafe impl Foo for Bar {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: declaration of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:66:5
+  --> $DIR/lint-unsafe-code.rs:69:5
    |
 LL |     unsafe fn baz(&self);
    |     ^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:67:5
+  --> $DIR/lint-unsafe-code.rs:70:5
    |
 LL |     unsafe fn provided(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:68:5
+  --> $DIR/lint-unsafe-code.rs:71:5
    |
 LL |     unsafe fn provided_override(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:72:5
+  --> $DIR/lint-unsafe-code.rs:75:5
    |
 LL |     unsafe fn baz(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:73:5
+  --> $DIR/lint-unsafe-code.rs:76:5
    |
 LL |     unsafe fn provided_override(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:92:5
+  --> $DIR/lint-unsafe-code.rs:95:5
    |
 LL |     unsafe fn provided_override(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:103:5
+  --> $DIR/lint-unsafe-code.rs:106:5
    |
 LL |     unsafe fn provided(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:109:5
+  --> $DIR/lint-unsafe-code.rs:112:5
    |
 LL |     unsafe fn provided(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:113:5
+  --> $DIR/lint-unsafe-code.rs:116:5
    |
 LL |     unsafe fn baz(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-unsafe-code.rs:124:5
+  --> $DIR/lint-unsafe-code.rs:127:5
    |
 LL |     unsafe {}
    |     ^^^^^^^^^
@@ -204,5 +220,5 @@ LL |     unsafe_in_macro!()
    |
    = note: this error originates in the macro `unsafe_in_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 26 previous errors
+error: aborting due to 28 previous errors