Unrolled build for #152302

Rollup merge of #152302 - ShE3py:cargo-envs, r=davidtwco

fix: don't suggest replacing `env!("CARGO_BIN_NAME")` with itself

Some environment variables (e.g. `CARGO_BIN_NAME`) are only available for some targets ([Cargo Targets](https://doc.rust-lang.org/cargo/reference/cargo-targets.html), [§ Environment variables Cargo sets for crates](https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates)), and the current diagnostic when copy-pasting code from a binary to a library is kinda confusing:

```rs
const _: &str = env!("CARGO_BIN_NAME");
```
Before:
```
error: environment variable `CARGO_BIN_NAME` not defined at compile time
 --> lib.rs:1:17
  |
1 | const _: &str = env!("CARGO_BIN_NAME");
  |                 ^^^^^^^^^^^^^^^^^^^^^^
  |
  = help: there is a similar Cargo environment variable: `CARGO_BIN_NAME`
```
After:
```
error: environment variable `CARGO_BIN_NAME` not defined at compile time
 --> lib.rs:1:17
  |
1 | const _: &str = env!("CARGO_BIN_NAME");
  |                 ^^^^^^^^^^^^^^^^^^^^^^
  |
  = help: `CARGO_BIN_NAME` may not be available for the current Cargo target
  = help: Cargo sets build script variables at run time. Use `std::env::var("CARGO_BIN_NAME")` instead
```

@rustbot label +T-compiler +A-diagnostics +D-confusing

Author: rust-timer

compiler/rustc_builtin_macros/src/env.rs

@@ -140,18 +140,21 @@ pub(crate) fn expand_env<'cx>(
                 unreachable!("`expr_to_string` ensures this is a string lit")
             };
 
+            let var = var.as_str();
             let guar = match err {
                 VarError::NotPresent => {
                     if let Some(msg_from_user) = custom_msg {
                         cx.dcx()
                             .emit_err(errors::EnvNotDefinedWithUserMessage { span, msg_from_user })
-                    } else if let Some(suggested_var) = find_similar_cargo_var(var.as_str()) {
+                    } else if let Some(suggested_var) = find_similar_cargo_var(var)
+                        && suggested_var != var
+                    {
                         cx.dcx().emit_err(errors::EnvNotDefined::CargoEnvVarTypo {
                             span,
                             var: *symbol,
                             suggested_var: Symbol::intern(suggested_var),
                         })
-                    } else if is_cargo_env_var(var.as_str()) {
+                    } else if is_cargo_env_var(var) {
                         cx.dcx().emit_err(errors::EnvNotDefined::CargoEnvVar {
                             span,
                             var: *symbol,
@@ -177,7 +180,7 @@ pub(crate) fn expand_env<'cx>(
     ExpandResult::Ready(MacEager::expr(e))
 }
 
-/// Returns `true` if an environment variable from `env!` is one used by Cargo.
+/// Returns `true` if an environment variable from `env!` could be one used by Cargo.
 fn is_cargo_env_var(var: &str) -> bool {
     var.starts_with("CARGO_")
         || var.starts_with("DEP_")
@@ -187,25 +190,28 @@ fn is_cargo_env_var(var: &str) -> bool {
 const KNOWN_CARGO_VARS: &[&str] = &[
     // List of known Cargo environment variables that are set for crates (not build scripts, OUT_DIR etc).
     // See: https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates
-    "CARGO_PKG_VERSION",
-    "CARGO_PKG_VERSION_MAJOR",
-    "CARGO_PKG_VERSION_MINOR",
-    "CARGO_PKG_VERSION_PATCH",
-    "CARGO_PKG_VERSION_PRE",
+    // tidy-alphabetical-start
+    "CARGO_BIN_NAME",
+    "CARGO_CRATE_NAME",
+    "CARGO_MANIFEST_DIR",
+    "CARGO_MANIFEST_PATH",
     "CARGO_PKG_AUTHORS",
-    "CARGO_PKG_NAME",
     "CARGO_PKG_DESCRIPTION",
     "CARGO_PKG_HOMEPAGE",
-    "CARGO_PKG_REPOSITORY",
     "CARGO_PKG_LICENSE",
     "CARGO_PKG_LICENSE_FILE",
-    "CARGO_PKG_RUST_VERSION",
+    "CARGO_PKG_NAME",
     "CARGO_PKG_README",
-    "CARGO_MANIFEST_DIR",
-    "CARGO_MANIFEST_PATH",
-    "CARGO_CRATE_NAME",
-    "CARGO_BIN_NAME",
+    "CARGO_PKG_REPOSITORY",
+    "CARGO_PKG_RUST_VERSION",
+    "CARGO_PKG_VERSION",
+    "CARGO_PKG_VERSION_MAJOR",
+    "CARGO_PKG_VERSION_MINOR",
+    "CARGO_PKG_VERSION_PATCH",
+    "CARGO_PKG_VERSION_PRE",
     "CARGO_PRIMARY_PACKAGE",
+    "CARGO_TARGET_TMPDIR",
+    // tidy-alphabetical-end
 ];
 
 fn find_similar_cargo_var(var: &str) -> Option<&'static str> {
@@ -219,7 +225,13 @@ fn find_similar_cargo_var(var: &str) -> Option<&'static str> {
     let mut best_distance = usize::MAX;
 
     for &known_var in KNOWN_CARGO_VARS {
-        if let Some(distance) = edit_distance(var, known_var, max_dist) {
+        if let Some(mut distance) = edit_distance(var, known_var, max_dist) {
+            // assume `PACKAGE` to equals `PKG`
+            // (otherwise, `d("CARGO_PACKAGE_NAME", "CARGO_PKG_NAME") == d("CARGO_PACKAGE_NAME", "CARGO_CRATE_NAME") == 4`)
+            if var.contains("PACKAGE") && known_var.contains("PKG") {
+                distance = distance.saturating_sub(const { "PACKAGE".len() - "PKG".len() }) // == d("PACKAGE", "PKG")
+            }
+
             if distance < best_distance {
                 best_distance = distance;
                 best_match = Some(known_var);

compiler/rustc_builtin_macros/src/errors.rs

@@ -545,6 +545,7 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for EnvNotDefinedWithUserMessag
 #[derive(Diagnostic)]
 pub(crate) enum EnvNotDefined<'a> {
     #[diag("environment variable `{$var}` not defined at compile time")]
+    #[help("`{$var}` may not be available for the current Cargo target")]
     #[help(
         "Cargo sets build script variables at run time. Use `std::env::var({$var_expr})` instead"
     )]

tests/ui/env-macro/env-cargo-var-typo-issue-148439.rs

@@ -1,4 +1,5 @@
 //@ edition: 2021
+//@ compile-flags: --crate-type=lib
 
 // Regression test for issue #148439
 // Ensure that when using misspelled Cargo environment variables in env!(),
@@ -44,7 +45,14 @@ fn test_cargo_unknown_var() {
     // Cargo-prefixed but not similar to any known variable
     let _ = env!("CARGO_SOMETHING_TOTALLY_UNKNOWN");
     //~^ ERROR environment variable `CARGO_SOMETHING_TOTALLY_UNKNOWN` not defined at compile time
+    //~| HELP `CARGO_SOMETHING_TOTALLY_UNKNOWN` may not be available for the current Cargo target
     //~| HELP Cargo sets build script variables at run time. Use `std::env::var("CARGO_SOMETHING_TOTALLY_UNKNOWN")` instead
 }
 
-fn main() {}
+fn test_cargo_conditional_var() {
+    // Only set for binairies
+    let _ = env!("CARGO_BIN_NAME");
+    //~^ ERROR environment variable `CARGO_BIN_NAME` not defined at compile time
+    //~| HELP `CARGO_BIN_NAME` may not be available for the current Cargo target
+    //~| HELP Cargo sets build script variables at run time. Use `std::env::var("CARGO_BIN_NAME")` instead
+}

tests/ui/env-macro/env-cargo-var-typo-issue-148439.stderr

@@ -1,58 +1,68 @@
 error: environment variable `CARGO_PACKAGE_VERSION` not defined at compile time
-  --> $DIR/env-cargo-var-typo-issue-148439.rs:7:13
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:8:13
    |
 LL |     let _ = env!("CARGO_PACKAGE_VERSION");
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: there is a similar Cargo environment variable: `CARGO_PKG_VERSION`
 
 error: environment variable `CARGO_PACKAGE_NAME` not defined at compile time
-  --> $DIR/env-cargo-var-typo-issue-148439.rs:13:13
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:14:13
    |
 LL |     let _ = env!("CARGO_PACKAGE_NAME");
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: there is a similar Cargo environment variable: `CARGO_PKG_NAME`
 
 error: environment variable `CARGO_PACKAGE_AUTHORS` not defined at compile time
-  --> $DIR/env-cargo-var-typo-issue-148439.rs:19:13
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:20:13
    |
 LL |     let _ = env!("CARGO_PACKAGE_AUTHORS");
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: there is a similar Cargo environment variable: `CARGO_PKG_AUTHORS`
 
 error: environment variable `CARGO_MANIFEST_DIRECTORY` not defined at compile time
-  --> $DIR/env-cargo-var-typo-issue-148439.rs:25:13
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:26:13
    |
 LL |     let _ = env!("CARGO_MANIFEST_DIRECTORY");
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: there is a similar Cargo environment variable: `CARGO_MANIFEST_DIR`
 
 error: environment variable `CARGO_PKG_VERSIO` not defined at compile time
-  --> $DIR/env-cargo-var-typo-issue-148439.rs:31:13
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:32:13
    |
 LL |     let _ = env!("CARGO_PKG_VERSIO");
    |             ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: there is a similar Cargo environment variable: `CARGO_PKG_VERSION`
 
 error: environment variable `MY_CUSTOM_VAR` not defined at compile time
-  --> $DIR/env-cargo-var-typo-issue-148439.rs:38:13
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:39:13
    |
 LL |     let _ = env!("MY_CUSTOM_VAR");
    |             ^^^^^^^^^^^^^^^^^^^^^
    |
    = help: use `std::env::var("MY_CUSTOM_VAR")` to read the variable at run time
 
 error: environment variable `CARGO_SOMETHING_TOTALLY_UNKNOWN` not defined at compile time
-  --> $DIR/env-cargo-var-typo-issue-148439.rs:45:13
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:46:13
    |
 LL |     let _ = env!("CARGO_SOMETHING_TOTALLY_UNKNOWN");
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
+   = help: `CARGO_SOMETHING_TOTALLY_UNKNOWN` may not be available for the current Cargo target
    = help: Cargo sets build script variables at run time. Use `std::env::var("CARGO_SOMETHING_TOTALLY_UNKNOWN")` instead
 
-error: aborting due to 7 previous errors
+error: environment variable `CARGO_BIN_NAME` not defined at compile time
+  --> $DIR/env-cargo-var-typo-issue-148439.rs:54:13
+   |
+LL |     let _ = env!("CARGO_BIN_NAME");
+   |             ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: `CARGO_BIN_NAME` may not be available for the current Cargo target
+   = help: Cargo sets build script variables at run time. Use `std::env::var("CARGO_BIN_NAME")` instead
+
+error: aborting due to 8 previous errors
 

tests/ui/env-macro/env-not-defined-default.stderr

@@ -4,6 +4,7 @@ error: environment variable `CARGO__HOPEFULLY_NOT_DEFINED__` not defined at comp
 LL |     env!("CARGO__HOPEFULLY_NOT_DEFINED__");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
+   = help: `CARGO__HOPEFULLY_NOT_DEFINED__` may not be available for the current Cargo target
    = help: Cargo sets build script variables at run time. Use `std::env::var("CARGO__HOPEFULLY_NOT_DEFINED__")` instead
 
 error: aborting due to 1 previous error