Auto merge of #126158 - Urgau:disallow-cfgs, r=petrochenkov

Disallow setting some built-in cfg via set the command-line

This PR disallow users from setting some built-in cfg via set the command-line in order to prevent incoherent state, eg. `windows` cfg active but target is Linux based.

This implements MCP https://github.com/rust-lang/compiler-team/issues/610, with the caveat that we disallow cfgs no matter if they make sense or not, since I don't think it's useful to allow users to set a cfg that will be set anyway. It also complicates the implementation.

------

The `explicit_builtin_cfgs_in_flags` lint detects builtin cfgs set via the `--cfg` flag.

*(deny-by-default)*

### Example

```text
rustc --cfg unix
```

```rust,ignore (needs command line option)
fn main() {}
```

This will produce:

```text
error: unexpected `--cfg unix` flag
  |
  = note: config `unix` is only supposed to be controlled by `--target`
  = note: manually setting a built-in cfg can and does create incoherent behaviours
  = note: `#[deny(explicit_builtin_cfgs_in_flags)]` on by default
```

### Explanation

Setting builtin cfgs can and does produce incoherent behaviour, it's better to the use the appropriate `rustc` flag that controls the config. For example setting the `windows` cfg but on Linux based target.

-----

r? `@petrochenkov`
cc `@jyn514`

try-job: aarch64-apple
try-job: test-various
try-job: armhf-gnu
try-job: x86_64-msvc
try-job: x86_64-mingw
try-job: i686-msvc
try-job: i686-mingw
try-job: x86_64-gnu-llvm-17
try-job: dist-various-1

1 files changed, 15 insertions, 15 deletions

diff --git a/tests/codegen/instrument-coverage/testprog.rs b/tests/codegen/instrument-coverage/testprog.rs
index eea4d9cb3cf..655fe779fca 100644
--- a/tests/codegen/instrument-coverage/testprog.rs
+++ b/tests/codegen/instrument-coverage/testprog.rs
@@ -1,7 +1,7 @@
 //@ edition: 2021
 //@ compile-flags: -Zno-profiler-runtime
 //@ compile-flags: -Cinstrument-coverage -Copt-level=0
-//@ revisions: LINUX DARWIN WINDOWS
+//@ revisions: LINUX DARWIN WIN
 
 //@ [LINUX] only-linux
 //@ [LINUX] filecheck-flags: -DINSTR_PROF_DATA=__llvm_prf_data
@@ -19,13 +19,13 @@
 //@ [DARWIN] filecheck-flags: -DINSTR_PROF_COVFUN=__LLVM_COV,__llvm_covfun
 //@ [DARWIN] filecheck-flags: -DCOMDAT_IF_SUPPORTED=
 
-//@ [WINDOWS] only-windows
-//@ [WINDOWS] filecheck-flags: -DINSTR_PROF_DATA=.lprfd$M
-//@ [WINDOWS] filecheck-flags: -DINSTR_PROF_NAME=.lprfn$M
-//@ [WINDOWS] filecheck-flags: -DINSTR_PROF_CNTS=.lprfc$M
-//@ [WINDOWS] filecheck-flags: -DINSTR_PROF_COVMAP=.lcovmap$M
-//@ [WINDOWS] filecheck-flags: -DINSTR_PROF_COVFUN=.lcovfun$M
-//@ [WINDOWS] filecheck-flags: '-DCOMDAT_IF_SUPPORTED=, comdat'
+//@ [WIN] only-windows
+//@ [WIN] filecheck-flags: -DINSTR_PROF_DATA=.lprfd$M
+//@ [WIN] filecheck-flags: -DINSTR_PROF_NAME=.lprfn$M
+//@ [WIN] filecheck-flags: -DINSTR_PROF_CNTS=.lprfc$M
+//@ [WIN] filecheck-flags: -DINSTR_PROF_COVMAP=.lcovmap$M
+//@ [WIN] filecheck-flags: -DINSTR_PROF_COVFUN=.lcovfun$M
+//@ [WIN] filecheck-flags: '-DCOMDAT_IF_SUPPORTED=, comdat'
 
 // ignore-tidy-linelength
 
@@ -71,7 +71,7 @@ fn main() {
 // Check for metadata, variables, declarations, and function definitions injected
 // into LLVM IR when compiling with -Cinstrument-coverage.
 
-// WINDOWS:      $__llvm_profile_runtime_user = comdat any
+// WIN:          $__llvm_profile_runtime_user = comdat any
 
 // CHECK:        @__llvm_coverage_mapping = private constant
 // CHECK-SAME:   section "[[INSTR_PROF_COVMAP]]", align 8
@@ -79,7 +79,7 @@ fn main() {
 // CHECK:        @__covrec_{{[A-F0-9]+}}u = linkonce_odr hidden constant
 // CHECK-SAME:   section "[[INSTR_PROF_COVFUN]]"[[COMDAT_IF_SUPPORTED]], align 8
 
-// WINDOWS:      @__llvm_profile_runtime = external{{.*}}global i32
+// WIN:          @__llvm_profile_runtime = external{{.*}}global i32
 
 // CHECK:        @__profc__R{{[a-zA-Z0-9_]+}}testprog14will_be_called = {{private|internal}} global
 // CHECK-SAME:   section "[[INSTR_PROF_CNTS]]"{{.*}}, align 8
@@ -111,10 +111,10 @@ fn main() {
 
 // CHECK:        declare void @llvm.instrprof.increment(ptr, i64, i32, i32) #[[LLVM_INSTRPROF_INCREMENT_ATTR:[0-9]+]]
 
-// WINDOWS:      define linkonce_odr hidden i32 @__llvm_profile_runtime_user() #[[LLVM_PROFILE_RUNTIME_USER_ATTR:[0-9]+]] comdat {
-// WINDOWS-NEXT: %1 = load i32, ptr @__llvm_profile_runtime
-// WINDOWS-NEXT: ret i32 %1
-// WINDOWS-NEXT: }
+// WIN:          define linkonce_odr hidden i32 @__llvm_profile_runtime_user() #[[LLVM_PROFILE_RUNTIME_USER_ATTR:[0-9]+]] comdat {
+// WIN-NEXT:     %1 = load i32, ptr @__llvm_profile_runtime
+// WIN-NEXT:     ret i32 %1
+// WIN-NEXT:     }
 
 // CHECK:        attributes #[[LLVM_INSTRPROF_INCREMENT_ATTR]] = { nounwind }
-// WINDOWS:      attributes #[[LLVM_PROFILE_RUNTIME_USER_ATTR]] = { noinline }
+// WIN:          attributes #[[LLVM_PROFILE_RUNTIME_USER_ATTR]] = { noinline }