Auto merge of #113483 - Mark-Simulacrum:beta-backport, r=Mark-Simulacrum

[beta] backport

This PR backports:
- #113334: Revert the lexing of `c"…"` string literals
- #113231: Fix `dropping_copy_types` lint from linting in match-arm with side-effects
- #112794: Fix linker failures when #[global_allocator] is used in a dependency

r? `@Mark-Simulacrum`

Author: bors

Cargo.lock

@@ -4,16 +4,25 @@ version = 3
 
 [[package]]
 name = "addr2line"
-version = "0.19.0"
+version = "0.18.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a76fd60b23679b7d19bd066031410fb7e458ccc5e958eb5c325888ce4baedc97"
+checksum = "6ca9b76e919fd83ccfb509f51b28c333c0e03f2221616e347a129215cec4e4a9"
 dependencies = [
  "compiler_builtins",
- "gimli 0.27.2",
+ "gimli 0.26.2",
  "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
 ]
 
+[[package]]
+name = "addr2line"
+version = "0.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a76fd60b23679b7d19bd066031410fb7e458ccc5e958eb5c325888ce4baedc97"
+dependencies = [
+ "gimli 0.27.2",
+]
+
 [[package]]
 name = "adler"
 version = "1.0.2"
@@ -228,7 +237,7 @@ version = "0.3.67"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "233d376d6d185f2a3093e58f283f60f880315b6c60075b01f36b3b85154564ca"
 dependencies = [
- "addr2line",
+ "addr2line 0.19.0",
  "cc",
  "cfg-if",
  "libc",
@@ -1524,8 +1533,11 @@ version = "0.26.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "22030e2c5a68ec659fde1e949a745124b48e6fa8b045b7ed5bd1fe4ccc5c4e5d"
 dependencies = [
+ "compiler_builtins",
  "fallible-iterator",
  "indexmap",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
  "stable_deref_trait",
 ]
 
@@ -1534,11 +1546,6 @@ name = "gimli"
 version = "0.27.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ad0a93d233ebf96623465aad4046a8d3aa4da22d4f4beba5388838c8a434bbb4"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
-]
 
 [[package]]
 name = "glob"
@@ -4718,7 +4725,7 @@ checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 name = "std"
 version = "0.0.0"
 dependencies = [
- "addr2line",
+ "addr2line 0.18.0",
  "alloc",
  "cfg-if",
  "compiler_builtins",

compiler/rustc_codegen_ssa/src/base.rs

@@ -13,7 +13,7 @@ use crate::mir::place::PlaceRef;
 use crate::traits::*;
 use crate::{CachedModuleCodegen, CompiledModule, CrateInfo, MemFlags, ModuleCodegen, ModuleKind};
 
-use rustc_ast::expand::allocator::AllocatorKind;
+use rustc_ast::expand::allocator::{global_fn_name, AllocatorKind, ALLOCATOR_METHODS};
 use rustc_attr as attr;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::profiling::{get_resident_set_size, print_time_passes_entry};
@@ -909,7 +909,21 @@ impl CrateInfo {
                         missing_weak_lang_items
                             .iter()
                             .map(|item| (format!("{prefix}{item}"), SymbolExportKind::Text)),
-                    )
+                    );
+                    if tcx.allocator_kind(()).is_some() {
+                        // At least one crate needs a global allocator. This crate may be placed
+                        // after the crate that defines it in the linker order, in which case some
+                        // linkers return an error. By adding the global allocator shim methods to
+                        // the linked_symbols list, linking the generated symbols.o will ensure that
+                        // circular dependencies involving the global allocator don't lead to linker
+                        // errors.
+                        linked_symbols.extend(ALLOCATOR_METHODS.iter().map(|method| {
+                            (
+                                format!("{prefix}{}", global_fn_name(method.name).as_str()),
+                                SymbolExportKind::Text,
+                            )
+                        }));
+                    }
                 });
         }
 

compiler/rustc_lexer/src/lib.rs

@@ -367,13 +367,6 @@ impl Cursor<'_> {
                 Some(|terminated| Byte { terminated }),
             ),
 
-            // c-string literal, raw c-string literal or identifier.
-            'c' => self.c_or_byte_string(
-                |terminated| CStr { terminated },
-                |n_hashes| RawCStr { n_hashes },
-                None,
-            ),
-
             // Identifier (this should be checked after other variant that can
             // start as identifier).
             c if is_id_start(c) => self.ident_or_unknown_prefix(),

compiler/rustc_lint/src/drop_forget_useless.rs

@@ -154,7 +154,7 @@ fn is_single_call_in_arm<'tcx>(
     arg: &'tcx Expr<'_>,
     drop_expr: &'tcx Expr<'_>,
 ) -> bool {
-    if matches!(arg.kind, ExprKind::Call(..) | ExprKind::MethodCall(..)) {
+    if arg.can_have_side_effects() {
         let parent_node = cx.tcx.hir().find_parent(drop_expr.hir_id);
         if let Some(Node::Arm(Arm { body, .. })) = &parent_node {
             return body.hir_id == drop_expr.hir_id;

library/std/Cargo.toml

@@ -23,7 +23,7 @@ hashbrown = { version = "0.13", default-features = false, features = ['rustc-dep
 std_detect = { path = "../stdarch/crates/std_detect", default-features = false, features = ['rustc-dep-of-std'] }
 
 # Dependencies of the `backtrace` crate
-addr2line = { version = "0.19.0", optional = true, default-features = false }
+addr2line = { version = "0.18.0", optional = true, default-features = false }
 rustc-demangle = { version = "0.1.21", features = ['rustc-dep-of-std'] }
 miniz_oxide = { version = "0.6.0", optional = true, default-features = false }
 [dependencies.object]

tests/run-make/allocator-shim-circular-deps/Makefile

@@ -0,0 +1,7 @@
+# ignore-cross-compile
+include ../tools.mk
+
+all:
+	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
+	$(RUSTC) my_lib.rs
+	$(RUSTC) main.rs --test --extern my_lib=$(TMPDIR)/libmy_lib.rlib

tests/run-make/allocator-shim-circular-deps/main.rs

@@ -0,0 +1,5 @@
+#![crate_type = "bin"]
+
+fn main() {
+    my_lib::do_something();
+}

tests/run-make/allocator-shim-circular-deps/my_lib.rs

@@ -0,0 +1,10 @@
+#![crate_type = "lib"]
+
+use std::alloc::System;
+
+#[global_allocator]
+static ALLOCATOR: System = System;
+
+pub fn do_something() {
+    format!("allocating a string!");
+}

tests/ui/lint/dropping_copy_types.rs

@@ -77,3 +77,22 @@ fn issue9482(x: u8) {
         _ => (),
     }
 }
+
+fn issue112653() {
+    fn foo() -> Result<u8, ()> {
+        println!("doing foo");
+        Ok(0) // result is not always useful, the side-effect matters
+    }
+    fn bar() {
+        println!("doing bar");
+    }
+
+    fn stuff() -> Result<(), ()> {
+        match 42 {
+            0 => drop(foo()?),  // drop is needed because we only care about side-effects
+            1 => bar(),
+            _ => (),  // doing nothing (no side-effects needed here)
+        }
+        Ok(())
+    }
+}

tests/ui/lint/dropping_references.rs

@@ -97,3 +97,22 @@ fn issue10122(x: u8) {
         _ => (),
     }
 }
+
+fn issue112653() {
+    fn foo() -> Result<&'static u8, ()> {
+        println!("doing foo");
+        Ok(&0) // result is not always useful, the side-effect matters
+    }
+    fn bar() {
+        println!("doing bar");
+    }
+
+    fn stuff() -> Result<(), ()> {
+        match 42 {
+            0 => drop(foo()?),  // drop is needed because we only care about side-effects
+            1 => bar(),
+            _ => (),  // doing nothing (no side-effects needed here)
+        }
+        Ok(())
+    }
+}