rustc_target: Add some more target spec sanity checking

compiler/rustc_target/src/spec/avr_gnu_base.rs

@@ -1,4 +1,4 @@
-use crate::spec::{LinkerFlavor, Target, TargetOptions};
+use crate::spec::{LinkerFlavor, RelocModel, Target, TargetOptions};
 
 /// A base target for AVR devices using the GNU toolchain.
 ///
@@ -21,6 +21,7 @@ pub fn target(target_cpu: &'static str, mmcu: &'static str) -> Target {
             late_link_args: TargetOptions::link_args(LinkerFlavor::Gcc, &["-lgcc"]),
             max_atomic_width: Some(0),
             atomic_cas: false,
+            relocation_model: RelocModel::Static,
             ..TargetOptions::default()
         },
     }

compiler/rustc_target/src/spec/l4re_base.rs

@@ -1,4 +1,4 @@
-use crate::spec::{cvs, LinkerFlavor, PanicStrategy, TargetOptions};
+use crate::spec::{cvs, LinkerFlavor, PanicStrategy, RelocModel, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     TargetOptions {
@@ -9,6 +9,7 @@ pub fn opts() -> TargetOptions {
         linker: Some("l4-bender".into()),
         linker_is_gnu: false,
         families: cvs!["unix"],
+        relocation_model: RelocModel::Static,
         ..Default::default()
     }
 }

compiler/rustc_target/src/spec/mod.rs

@@ -837,15 +837,15 @@ impl fmt::Display for StackProtector {
 }
 
 macro_rules! supported_targets {
-    ( $(($( $triple:literal, )+ $module:ident ),)+ ) => {
+    ( $(($triple:literal, $module:ident ),)+ ) => {
         $(mod $module;)+
 
         /// List of supported targets
-        pub const TARGETS: &[&str] = &[$($($triple),+),+];
+        pub const TARGETS: &[&str] = &[$($triple),+];
 
         fn load_builtin(target: &str) -> Option<Target> {
             let mut t = match target {
-                $( $($triple)|+ => $module::target(), )+
+                $( $triple => $module::target(), )+
                 _ => return None,
             };
             t.is_builtin = true;
@@ -861,7 +861,7 @@ macro_rules! supported_targets {
             $(
                 #[test] // `#[test]`
                 fn $module() {
-                    tests_impl::test_target(super::$module::target());
+                    tests_impl::test_target(super::$module::target(), $triple);
                 }
             )+
         }

compiler/rustc_target/src/spec/tests/tests_impl.rs

@@ -2,18 +2,20 @@ use super::super::*;
 use std::assert_matches::assert_matches;
 
 // Test target self-consistency and JSON encoding/decoding roundtrip.
-pub(super) fn test_target(target: Target) {
-    target.check_consistency();
+pub(super) fn test_target(target: Target, triple: &str) {
+    target.check_consistency(triple);
     assert_eq!(Target::from_json(target.to_json()).map(|(j, _)| j), Ok(target));
 }
 
 impl Target {
-    fn check_consistency(&self) {
+    fn check_consistency(&self, triple: &str) {
         assert_eq!(self.is_like_osx, self.vendor == "apple");
         assert_eq!(self.is_like_solaris, self.os == "solaris" || self.os == "illumos");
         assert_eq!(self.is_like_windows, self.os == "windows" || self.os == "uefi");
         assert_eq!(self.is_like_wasm, self.arch == "wasm32" || self.arch == "wasm64");
-        assert!(self.is_like_windows || !self.is_like_msvc);
+        if self.is_like_msvc {
+            assert!(self.is_like_windows);
+        }
 
         // Check that default linker flavor and lld flavor are compatible
         // with some other key properties.
@@ -94,8 +96,9 @@ impl Target {
                             check_noncc(LinkerFlavor::Ld);
                             check_noncc(LinkerFlavor::Lld(LldFlavor::Ld));
                         }
+                        LldFlavor::Ld64 => check_noncc(LinkerFlavor::Lld(LldFlavor::Ld64)),
                         LldFlavor::Wasm => check_noncc(LinkerFlavor::Lld(LldFlavor::Wasm)),
-                        LldFlavor::Ld64 | LldFlavor::Link => {}
+                        LldFlavor::Link => {}
                     },
                     _ => {}
                 }
@@ -109,20 +112,56 @@ impl Target {
             );
         }
 
-        assert!(
-            (self.pre_link_objects_self_contained.is_empty()
-                && self.post_link_objects_self_contained.is_empty())
-                || self.link_self_contained != LinkSelfContainedDefault::False
-        );
+        if self.link_self_contained == LinkSelfContainedDefault::False {
+            assert!(
+                self.pre_link_objects_self_contained.is_empty()
+                    && self.post_link_objects_self_contained.is_empty()
+            );
+        }
 
         // If your target really needs to deviate from the rules below,
         // except it and document the reasons.
         // Keep the default "unknown" vendor instead.
         assert_ne!(self.vendor, "");
+        assert_ne!(self.os, "");
         if !self.can_use_os_unknown() {
             // Keep the default "none" for bare metal targets instead.
             assert_ne!(self.os, "unknown");
         }
+
+        // Check dynamic linking stuff
+        // BPF: when targeting user space vms (like rbpf), those can load dynamic libraries.
+        if self.os == "none" && self.arch != "bpf" {
+            assert!(!self.dynamic_linking);
+        }
+        if self.only_cdylib
+            || self.crt_static_allows_dylibs
+            || !self.late_link_args_dynamic.is_empty()
+        {
+            assert!(self.dynamic_linking);
+        }
+        // Apparently PIC was slow on wasm at some point, see comments in wasm_base.rs
+        if self.dynamic_linking && !(self.is_like_wasm && self.os != "emscripten") {
+            assert_eq!(self.relocation_model, RelocModel::Pic);
+        }
+        // PIEs are supported but not enabled by default with linuxkernel target.
+        if self.position_independent_executables && !triple.ends_with("-linuxkernel") {
+            assert_eq!(self.relocation_model, RelocModel::Pic);
+        }
+        if self.relocation_model == RelocModel::Pic {
+            assert!(self.dynamic_linking || self.position_independent_executables);
+        }
+        if self.static_position_independent_executables {
+            assert!(self.position_independent_executables);
+        }
+        if self.position_independent_executables {
+            assert!(self.executables);
+        }
+
+        // Check crt static stuff
+        if self.crt_static_default || self.crt_static_allows_dylibs {
+            assert!(self.crt_static_respected);
+        }
     }
 
     // Add your target to the whitelist if it has `std` library

compiler/rustc_target/src/spec/uefi_msvc_base.rs

@@ -9,7 +9,8 @@
 // the timer-interrupt. Device-drivers are required to use polling-based models. Furthermore, all
 // code runs in the same environment, no process separation is supported.
 
-use crate::spec::{LinkerFlavor, LldFlavor, PanicStrategy, StackProbeType, TargetOptions};
+use crate::spec::{LinkerFlavor, LldFlavor, PanicStrategy};
+use crate::spec::{RelocModel, StackProbeType, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     let mut base = super::msvc_base::opts();
@@ -46,6 +47,7 @@ pub fn opts() -> TargetOptions {
         stack_probes: StackProbeType::Call,
         singlethread: true,
         linker: Some("rust-lld".into()),
+        relocation_model: RelocModel::Static,
         ..base
     }
 }