From 2407b0c5787e731f9ed39ad180d87de166fa54bf Mon Sep 17 00:00:00 2001 From: Kornel Date: Tue, 28 Feb 2023 16:20:43 +0000 Subject: [PATCH] Explain compile-time vs run-time difference in env!() error message --- compiler/rustc_builtin_macros/src/env.rs | 40 ++++++++++++++----- tests/ui/extenv/extenv-not-defined-default.rs | 4 +- .../extenv/extenv-not-defined-default.stderr | 7 ++-- tests/ui/extenv/issue-55897.stderr | 3 +- tests/ui/macros/macros-nonfatal-errors.stderr | 9 +++-- 5 files changed, 43 insertions(+), 20 deletions(-) diff --git a/compiler/rustc_builtin_macros/src/env.rs b/compiler/rustc_builtin_macros/src/env.rs index 6aa900f020163..f011cb754cb4a 100644 --- a/compiler/rustc_builtin_macros/src/env.rs +++ b/compiler/rustc_builtin_macros/src/env.rs @@ -53,7 +53,7 @@ pub fn expand_env<'cx>( tts: TokenStream, ) -> Box { let mut exprs = match get_exprs_from_tts(cx, tts) { - Some(exprs) if exprs.is_empty() => { + Some(exprs) if exprs.is_empty() || exprs.len() > 2 => { cx.span_err(sp, "env! takes 1 or 2 arguments"); return DummyResult::any(sp); } @@ -64,28 +64,48 @@ pub fn expand_env<'cx>( let Some((var, _style)) = expr_to_string(cx, exprs.next().unwrap(), "expected string literal") else { return DummyResult::any(sp); }; - let msg = match exprs.next() { - None => Symbol::intern(&format!("environment variable `{}` not defined", var)), + + let custom_msg = match exprs.next() { + None => None, Some(second) => match expr_to_string(cx, second, "expected string literal") { None => return DummyResult::any(sp), - Some((s, _style)) => s, + Some((s, _style)) => Some(s), }, }; - if exprs.next().is_some() { - cx.span_err(sp, "env! takes 1 or 2 arguments"); - return DummyResult::any(sp); - } - let sp = cx.with_def_site_ctxt(sp); let value = env::var(var.as_str()).ok().as_deref().map(Symbol::intern); cx.sess.parse_sess.env_depinfo.borrow_mut().insert((var, value)); let e = match value { None => { - cx.span_err(sp, msg.as_str()); + let (msg, help) = match custom_msg { + None => ( + format!("environment variable `{var}` not defined at compile time"), + Some(help_for_missing_env_var(var.as_str())), + ), + Some(s) => (s.to_string(), None), + }; + let mut diag = cx.struct_span_err(sp, &msg); + if let Some(help) = help { + diag.help(help); + } + diag.emit(); return DummyResult::any(sp); } Some(value) => cx.expr_str(sp, value), }; MacEager::expr(e) } + +fn help_for_missing_env_var(var: &str) -> String { + if var.starts_with("CARGO_") + || var.starts_with("DEP_") + || matches!(var, "OUT_DIR" | "OPT_LEVEL" | "PROFILE" | "HOST" | "TARGET") + { + format!( + "Cargo sets build script variables at run time. Use `std::env::var(\"{var}\")` instead" + ) + } else { + format!("Use `std::env::var(\"{var}\")` to read the variable at run time") + } +} diff --git a/tests/ui/extenv/extenv-not-defined-default.rs b/tests/ui/extenv/extenv-not-defined-default.rs index 30a06a25465f4..1fb046c78f2a0 100644 --- a/tests/ui/extenv/extenv-not-defined-default.rs +++ b/tests/ui/extenv/extenv-not-defined-default.rs @@ -1,4 +1,4 @@ fn main() { - env!("__HOPEFULLY_NOT_DEFINED__"); - //~^ ERROR: environment variable `__HOPEFULLY_NOT_DEFINED__` not defined + env!("CARGO__HOPEFULLY_NOT_DEFINED__"); + //~^ ERROR: environment variable `CARGO__HOPEFULLY_NOT_DEFINED__` not defined } diff --git a/tests/ui/extenv/extenv-not-defined-default.stderr b/tests/ui/extenv/extenv-not-defined-default.stderr index 884875dca5394..e3dce000530ae 100644 --- a/tests/ui/extenv/extenv-not-defined-default.stderr +++ b/tests/ui/extenv/extenv-not-defined-default.stderr @@ -1,9 +1,10 @@ -error: environment variable `__HOPEFULLY_NOT_DEFINED__` not defined +error: environment variable `CARGO__HOPEFULLY_NOT_DEFINED__` not defined at compile time --> $DIR/extenv-not-defined-default.rs:2:5 | -LL | env!("__HOPEFULLY_NOT_DEFINED__"); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +LL | env!("CARGO__HOPEFULLY_NOT_DEFINED__"); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | + = help: Cargo sets build script variables at run time. Use `std::env::var("CARGO__HOPEFULLY_NOT_DEFINED__")` instead = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info) error: aborting due to previous error diff --git a/tests/ui/extenv/issue-55897.stderr b/tests/ui/extenv/issue-55897.stderr index 92e8a44b55fe5..5752a965e3518 100644 --- a/tests/ui/extenv/issue-55897.stderr +++ b/tests/ui/extenv/issue-55897.stderr @@ -1,9 +1,10 @@ -error: environment variable `NON_EXISTENT` not defined +error: environment variable `NON_EXISTENT` not defined at compile time --> $DIR/issue-55897.rs:11:22 | LL | include!(concat!(env!("NON_EXISTENT"), "/data.rs")); | ^^^^^^^^^^^^^^^^^^^^ | + = help: Use `std::env::var("NON_EXISTENT")` to read the variable at run time = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info) error: suffixes on string literals are invalid diff --git a/tests/ui/macros/macros-nonfatal-errors.stderr b/tests/ui/macros/macros-nonfatal-errors.stderr index d42f6c179b7ef..93fbc9c8a447e 100644 --- a/tests/ui/macros/macros-nonfatal-errors.stderr +++ b/tests/ui/macros/macros-nonfatal-errors.stderr @@ -150,18 +150,19 @@ error: expected string literal LL | env!(invalid); | ^^^^^^^ -error: expected string literal - --> $DIR/macros-nonfatal-errors.rs:105:10 +error: env! takes 1 or 2 arguments + --> $DIR/macros-nonfatal-errors.rs:105:5 | LL | env!(foo, abr, baz); - | ^^^ + | ^^^^^^^^^^^^^^^^^^^ -error: environment variable `RUST_HOPEFULLY_THIS_DOESNT_EXIST` not defined +error: environment variable `RUST_HOPEFULLY_THIS_DOESNT_EXIST` not defined at compile time --> $DIR/macros-nonfatal-errors.rs:106:5 | LL | env!("RUST_HOPEFULLY_THIS_DOESNT_EXIST"); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | + = help: Use `std::env::var("RUST_HOPEFULLY_THIS_DOESNT_EXIST")` to read the variable at run time = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info) error: format argument must be a string literal