Adjust wording for --cfg/--check-cfg errors

Author: mu001999

compiler/rustc_interface/src/interface.rs

@@ -85,7 +85,9 @@ pub(crate) fn parse_cfg(dcx: DiagCtxtHandle<'_>, cfgs: Vec<String>) -> Cfg {
                                     let ident = meta_item.ident().expect("multi-segment cfg key");
 
                                     if !ident.name.can_be_raw() {
-                                        error!("argument key must be an identifier");
+                                        error!(
+                                            "malformed `cfg` input, expected a valid identifier"
+                                        );
                                     }
 
                                     return (ident.name, meta_item.value_str());
@@ -223,7 +225,7 @@ pub(crate) fn parse_check_cfg(dcx: DiagCtxtHandle<'_>, specs: Vec<String>) -> Ch
                 }
 
                 if !ident.name.can_be_raw() {
-                    error!("`cfg()` names must be identifiers");
+                    error!("malformed `cfg` input, expected a valid identifier");
                 }
 
                 names.push(ident);

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_crate.stderr

@@ -1,2 +1,2 @@
-error: invalid `--cfg` argument: `crate` (argument key must be an identifier)
+error: invalid `--cfg` argument: `crate` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_raw_crate.stderr

@@ -2,5 +2,5 @@ error: `crate` cannot be a raw identifier
   |
   = note: this occurred on the command line: `--cfg=r#crate`
 
-error: invalid `--cfg` argument: `r#crate` (argument key must be an identifier)
+error: invalid `--cfg` argument: `r#crate` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_raw_self_lower.stderr

@@ -2,5 +2,5 @@ error: `self` cannot be a raw identifier
   |
   = note: this occurred on the command line: `--cfg=r#self`
 
-error: invalid `--cfg` argument: `r#self` (argument key must be an identifier)
+error: invalid `--cfg` argument: `r#self` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_raw_self_upper.stderr

@@ -2,5 +2,5 @@ error: `Self` cannot be a raw identifier
   |
   = note: this occurred on the command line: `--cfg=r#Self`
 
-error: invalid `--cfg` argument: `r#Self` (argument key must be an identifier)
+error: invalid `--cfg` argument: `r#Self` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_raw_super.stderr

@@ -2,5 +2,5 @@ error: `super` cannot be a raw identifier
   |
   = note: this occurred on the command line: `--cfg=r#super`
 
-error: invalid `--cfg` argument: `r#super` (argument key must be an identifier)
+error: invalid `--cfg` argument: `r#super` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_raw_underscore.stderr

@@ -2,5 +2,5 @@ error: `_` cannot be a raw identifier
   |
   = note: this occurred on the command line: `--cfg=r#_`
 
-error: invalid `--cfg` argument: `r#_` (argument key must be an identifier)
+error: invalid `--cfg` argument: `r#_` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_self_lower.stderr

@@ -1,2 +1,2 @@
-error: invalid `--cfg` argument: `self` (argument key must be an identifier)
+error: invalid `--cfg` argument: `self` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_self_upper.stderr

@@ -1,2 +1,2 @@
-error: invalid `--cfg` argument: `Self` (argument key must be an identifier)
+error: invalid `--cfg` argument: `Self` (malformed `cfg` input, expected a valid identifier)
 

tests/ui/cfg/path-kw-as-cfg-pred-cli-cfg.cfg_super.stderr

@@ -1,2 +1,2 @@
-error: invalid `--cfg` argument: `super` (argument key must be an identifier)
+error: invalid `--cfg` argument: `super` (malformed `cfg` input, expected a valid identifier)