Rollup merge of #138483 - azhogin:azhogin/target-modifiers-bool-fix, r=fee1-dead

Target modifiers fix for bool flags without value

Fixed support of boolean flags without values: `-Zbool-flag` is now consistent with `-Zbool-flag=true` in another crate.

When flag is explicitly set to default value, target modifier will not be set in crate metainfo (`-Zflag=false` when `false` is a default value for the flag).

Improved error notification when target modifier flag is absent in a crate ("-Zflag unset").
Example:
```
note: `-Zreg-struct-return=true` in this crate is incompatible with unset `-Zreg-struct-return` in dependency `default_reg_struct_return`
```

5 files changed, 57 insertions, 2 deletions

diff --git a/tests/ui/target_modifiers/auxiliary/enabled_reg_struct_return.rs b/tests/ui/target_modifiers/auxiliary/enabled_reg_struct_return.rs
new file mode 100644
index 00000000000..4bda4ba24c5
--- /dev/null
+++ b/tests/ui/target_modifiers/auxiliary/enabled_reg_struct_return.rs
@@ -0,0 +1,7 @@
+//@ no-prefer-dynamic
+//@ compile-flags: --target i686-unknown-linux-gnu -Zreg-struct-return=true
+//@ needs-llvm-components: x86
+
+#![feature(no_core)]
+#![crate_type = "rlib"]
+#![no_core]
diff --git a/tests/ui/target_modifiers/defaults_check.error.stderr b/tests/ui/target_modifiers/defaults_check.error.stderr
index 4833fe90677..936fbbc94d6 100644
--- a/tests/ui/target_modifiers/defaults_check.error.stderr
+++ b/tests/ui/target_modifiers/defaults_check.error.stderr
@@ -5,8 +5,8 @@ LL | #![feature(no_core)]
    | ^
    |
    = help: the `-Zreg-struct-return` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
-   = note: `-Zreg-struct-return=true` in this crate is incompatible with `-Zreg-struct-return=` in dependency `default_reg_struct_return`
-   = help: set `-Zreg-struct-return=` in this crate or `-Zreg-struct-return=true` in `default_reg_struct_return`
+   = note: `-Zreg-struct-return=true` in this crate is incompatible with unset `-Zreg-struct-return` in dependency `default_reg_struct_return`
+   = help: unset `-Zreg-struct-return` in this crate or set `-Zreg-struct-return=true` in `default_reg_struct_return`
    = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=reg-struct-return` to silence this error
 
 error: aborting due to 1 previous error
diff --git a/tests/ui/target_modifiers/no_value_bool.error.stderr b/tests/ui/target_modifiers/no_value_bool.error.stderr
new file mode 100644
index 00000000000..0484960dc62
--- /dev/null
+++ b/tests/ui/target_modifiers/no_value_bool.error.stderr
@@ -0,0 +1,13 @@
+error: mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+  --> $DIR/no_value_bool.rs:16:1
+   |
+LL | #![feature(no_core)]
+   | ^
+   |
+   = help: the `-Zreg-struct-return` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+   = note: unset `-Zreg-struct-return` in this crate is incompatible with `-Zreg-struct-return=true` in dependency `enabled_reg_struct_return`
+   = help: set `-Zreg-struct-return=true` in this crate or unset `-Zreg-struct-return` in `enabled_reg_struct_return`
+   = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=reg-struct-return` to silence this error
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/target_modifiers/no_value_bool.error_explicit.stderr b/tests/ui/target_modifiers/no_value_bool.error_explicit.stderr
new file mode 100644
index 00000000000..0484960dc62
--- /dev/null
+++ b/tests/ui/target_modifiers/no_value_bool.error_explicit.stderr
@@ -0,0 +1,13 @@
+error: mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+  --> $DIR/no_value_bool.rs:16:1
+   |
+LL | #![feature(no_core)]
+   | ^
+   |
+   = help: the `-Zreg-struct-return` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+   = note: unset `-Zreg-struct-return` in this crate is incompatible with `-Zreg-struct-return=true` in dependency `enabled_reg_struct_return`
+   = help: set `-Zreg-struct-return=true` in this crate or unset `-Zreg-struct-return` in `enabled_reg_struct_return`
+   = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=reg-struct-return` to silence this error
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/target_modifiers/no_value_bool.rs b/tests/ui/target_modifiers/no_value_bool.rs
new file mode 100644
index 00000000000..ceba40afa89
--- /dev/null
+++ b/tests/ui/target_modifiers/no_value_bool.rs
@@ -0,0 +1,22 @@
+// Tests that bool target modifier value (true) in dependency crate is ok linked
+// with the -Zflag specified without value (-Zflag=true is consistent with -Zflag)
+
+//@ aux-build:enabled_reg_struct_return.rs
+//@ compile-flags: --target i686-unknown-linux-gnu -Cpanic=abort
+//@ needs-llvm-components: x86
+
+//@ revisions: ok ok_explicit error error_explicit
+//@[ok] compile-flags: -Zreg-struct-return
+//@[ok_explicit] compile-flags: -Zreg-struct-return=true
+//@[error] compile-flags:
+//@[error_explicit] compile-flags: -Zreg-struct-return=false
+//@[ok] check-pass
+//@[ok_explicit] check-pass
+
+#![feature(no_core)]
+//[error]~^ ERROR mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+//[error_explicit]~^^ ERROR mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+#![crate_type = "rlib"]
+#![no_core]
+
+extern crate enabled_reg_struct_return;