Honor current target when checking conditional compilation values

This is fixed by simply using the currently registered target in the
current session. We need to use it because of target json that are not
by design included in the rustc list of targets.

Author: Urgau

Diff for: compiler/rustc_interface/src/util.rs

@@ -110,7 +110,7 @@ pub fn create_session(
     add_configuration(&mut cfg, &mut sess, &*codegen_backend);
 
     let mut check_cfg = config::to_crate_check_config(check_cfg);
-    check_cfg.fill_well_known();
+    check_cfg.fill_well_known(&sess.target);
 
     sess.parse_sess.config = cfg;
     sess.parse_sess.check_config = check_cfg;

Diff for: compiler/rustc_session/src/config.rs

@@ -1137,7 +1137,7 @@ impl CrateCheckConfig {
     }
 
     /// Fills a `CrateCheckConfig` with well-known configuration values.
-    fn fill_well_known_values(&mut self) {
+    fn fill_well_known_values(&mut self, current_target: &Target) {
         if !self.well_known_values {
             return;
         }
@@ -1229,6 +1229,7 @@ impl CrateCheckConfig {
             for target in TARGETS
                 .iter()
                 .map(|target| Target::expect_builtin(&TargetTriple::from_triple(target)))
+                .chain(iter::once(current_target.clone()))
             {
                 values_target_os.insert(Symbol::intern(&target.options.os));
                 values_target_family
@@ -1243,9 +1244,9 @@ impl CrateCheckConfig {
         }
     }
 
-    pub fn fill_well_known(&mut self) {
+    pub fn fill_well_known(&mut self, current_target: &Target) {
         self.fill_well_known_names();
-        self.fill_well_known_values();
+        self.fill_well_known_values(current_target);
     }
 }
 

Diff for: tests/ui/check-cfg/my-awesome-platform.json

@@ -0,0 +1,12 @@
+{
+    "llvm-target": "x86_64-unknown-none-gnu",
+    "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+    "arch": "x86_64",
+    "target-endian": "little",
+    "target-pointer-width": "64",
+    "target-c-int-width": "32",
+    "os": "ericos",
+    "linker-flavor": "ld.lld",
+    "linker": "rust-lld",
+    "executables": true
+}

Diff for: tests/ui/check-cfg/values-target-json.rs

@@ -0,0 +1,21 @@
+// This test checks that we don't lint values defined by a custom target (target json)
+//
+// check-pass
+// needs-llvm-components: x86
+// compile-flags: --crate-type=lib --check-cfg=values() --target={{src-base}}/check-cfg/my-awesome-platform.json -Z unstable-options
+
+#![feature(lang_items, no_core, auto_traits)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[cfg(target_os = "linuz")]
+//~^ WARNING unexpected `cfg` condition value
+fn target_os_linux_misspell() {}
+
+#[cfg(target_os = "linux")]
+fn target_os_linux() {}
+
+#[cfg(target_os = "ericos")]
+fn target_os_ericos() {}

Diff for: tests/ui/check-cfg/values-target-json.stderr

@@ -0,0 +1,13 @@
+warning: unexpected `cfg` condition value
+  --> $DIR/values-target-json.rs:13:7
+   |
+LL | #[cfg(target_os = "linuz")]
+   |       ^^^^^^^^^^^^-------
+   |                   |
+   |                   help: did you mean: `"linux"`
+   |
+   = note: expected values for `target_os` are: aix, android, cuda, dragonfly, emscripten, ericos, espidf, freebsd, fuchsia, haiku, hermit, horizon, illumos, ios, l4re, linux, macos, netbsd, none, nto, openbsd, psp, redox, solaris, solid_asp3, tvos, uefi, unknown, vita, vxworks, wasi, watchos, windows, xous
+   = note: `#[warn(unexpected_cfgs)]` on by default
+
+warning: 1 warning emitted
+