implement range support in `//@ edition`

5 files changed, 270 insertions, 14 deletions

diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index 6d959948918..65db816ad1a 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -7,6 +7,7 @@ use build_helper::git::GitConfig;
 use camino::{Utf8Path, Utf8PathBuf};
 use semver::Version;
 
+use crate::edition::Edition;
 use crate::executor::ColorConfig;
 use crate::fatal;
 use crate::util::{Utf8PathBufExt, add_dylib_path, string_enum};
@@ -612,10 +613,7 @@ pub struct Config {
     pub git_hash: bool,
 
     /// The default Rust edition.
-    ///
-    /// FIXME: perform stronger validation for this. There are editions that *definitely* exists,
-    /// but there might also be "future" edition.
-    pub edition: Option<String>,
+    pub edition: Option<Edition>,
 
     // Configuration for various run-make tests frobbing things like C compilers or querying about
     // various LLVM component information.
diff --git a/src/tools/compiletest/src/directives.rs b/src/tools/compiletest/src/directives.rs
index 0d85e76c2cc..a79978d036c 100644
--- a/src/tools/compiletest/src/directives.rs
+++ b/src/tools/compiletest/src/directives.rs
@@ -16,10 +16,11 @@ use crate::directives::directive_names::{
     KNOWN_DIRECTIVE_NAMES, KNOWN_HTMLDOCCK_DIRECTIVE_NAMES, KNOWN_JSONDOCCK_DIRECTIVE_NAMES,
 };
 use crate::directives::needs::CachedNeedsConditions;
+use crate::edition::{Edition, parse_edition};
 use crate::errors::ErrorKind;
 use crate::executor::{CollectedTestDesc, ShouldPanic};
-use crate::help;
 use crate::util::static_regex;
+use crate::{fatal, help};
 
 pub(crate) mod auxiliary;
 mod cfg;
@@ -437,10 +438,13 @@ impl TestProps {
                         panic!("`compiler-flags` directive should be spelled `compile-flags`");
                     }
 
-                    if let Some(edition) = config.parse_edition(ln, testfile) {
+                    if let Some(range) = parse_edition_range(config, ln, testfile) {
                         // The edition is added at the start, since flags from //@compile-flags must
                         // be passed to rustc last.
-                        self.compile_flags.insert(0, format!("--edition={}", edition.trim()));
+                        self.compile_flags.insert(
+                            0,
+                            format!("--edition={}", range.edition_to_test(config.edition)),
+                        );
                         has_edition = true;
                     }
 
@@ -1124,10 +1128,6 @@ impl Config {
         }
     }
 
-    fn parse_edition(&self, line: &DirectiveLine<'_>, testfile: &Utf8Path) -> Option<String> {
-        self.parse_name_value_directive(line, "edition", testfile)
-    }
-
     fn set_name_directive(&self, line: &DirectiveLine<'_>, directive: &str, value: &mut bool) {
         // If the flag is already true, don't bother looking at the directive.
         *value = *value || self.parse_name_directive(line, directive);
@@ -1769,3 +1769,86 @@ enum IgnoreDecision {
     Continue,
     Error { message: String },
 }
+
+fn parse_edition_range(
+    config: &Config,
+    line: &DirectiveLine<'_>,
+    testfile: &Utf8Path,
+) -> Option<EditionRange> {
+    let raw = config.parse_name_value_directive(line, "edition", testfile)?;
+    let line_number = line.line_number;
+
+    // Edition range is half-open: `[lower_bound, upper_bound)`
+    if let Some((lower_bound, upper_bound)) = raw.split_once("..") {
+        Some(match (maybe_parse_edition(lower_bound), maybe_parse_edition(upper_bound)) {
+            (Some(lower_bound), Some(upper_bound)) if upper_bound <= lower_bound => {
+                fatal!(
+                    "{testfile}:{line_number}: the left side of `//@ edition` cannot be greater than or equal to the right side"
+                );
+            }
+            (Some(lower_bound), Some(upper_bound)) => {
+                EditionRange::Range { lower_bound, upper_bound }
+            }
+            (Some(lower_bound), None) => EditionRange::RangeFrom(lower_bound),
+            (None, Some(_)) => {
+                fatal!(
+                    "{testfile}:{line_number}: `..edition` is not a supported range in `//@ edition`"
+                );
+            }
+            (None, None) => {
+                fatal!("{testfile}:{line_number}: `..` is not a supported range in `//@ edition`");
+            }
+        })
+    } else {
+        match maybe_parse_edition(&raw) {
+            Some(edition) => Some(EditionRange::Exact(edition)),
+            None => {
+                fatal!("{testfile}:{line_number}: empty value for `//@ edition`");
+            }
+        }
+    }
+}
+
+fn maybe_parse_edition(mut input: &str) -> Option<Edition> {
+    input = input.trim();
+    if input.is_empty() {
+        return None;
+    }
+    Some(parse_edition(input))
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+enum EditionRange {
+    Exact(Edition),
+    RangeFrom(Edition),
+    /// Half-open range: `[lower_bound, upper_bound)`
+    Range {
+        lower_bound: Edition,
+        upper_bound: Edition,
+    },
+}
+
+impl EditionRange {
+    fn edition_to_test(&self, requested: impl Into<Option<Edition>>) -> Edition {
+        let min_edition = Edition::Year(2015);
+        let requested = requested.into().unwrap_or(min_edition);
+
+        match *self {
+            EditionRange::Exact(exact) => exact,
+            EditionRange::RangeFrom(lower_bound) => {
+                if requested >= lower_bound {
+                    requested
+                } else {
+                    lower_bound
+                }
+            }
+            EditionRange::Range { lower_bound, upper_bound } => {
+                if requested >= lower_bound && requested < upper_bound {
+                    requested
+                } else {
+                    lower_bound
+                }
+            }
+        }
+    }
+}
diff --git a/src/tools/compiletest/src/directives/tests.rs b/src/tools/compiletest/src/directives/tests.rs
index 16cf76be9a5..93621192d4b 100644
--- a/src/tools/compiletest/src/directives/tests.rs
+++ b/src/tools/compiletest/src/directives/tests.rs
@@ -4,10 +4,11 @@ use camino::Utf8Path;
 use semver::Version;
 
 use super::{
-    DirectivesCache, EarlyProps, extract_llvm_version, extract_version_range, iter_directives,
-    parse_normalize_rule,
+    DirectivesCache, EarlyProps, Edition, EditionRange, extract_llvm_version,
+    extract_version_range, iter_directives, parse_normalize_rule,
 };
 use crate::common::{Config, Debugger, TestMode};
+use crate::directives::parse_edition;
 use crate::executor::{CollectedTestDesc, ShouldPanic};
 
 fn make_test_description<R: Read>(
@@ -73,6 +74,7 @@ fn test_parse_normalize_rule() {
 struct ConfigBuilder {
     mode: Option<String>,
     channel: Option<String>,
+    edition: Option<Edition>,
     host: Option<String>,
     target: Option<String>,
     stage: Option<u32>,
@@ -96,6 +98,11 @@ impl ConfigBuilder {
         self
     }
 
+    fn edition(&mut self, e: Edition) -> &mut Self {
+        self.edition = Some(e);
+        self
+    }
+
     fn host(&mut self, s: &str) -> &mut Self {
         self.host = Some(s.to_owned());
         self
@@ -183,6 +190,10 @@ impl ConfigBuilder {
         ];
         let mut args: Vec<String> = args.iter().map(ToString::to_string).collect();
 
+        if let Some(edition) = &self.edition {
+            args.push(format!("--edition={edition}"));
+        }
+
         if let Some(ref llvm_version) = self.llvm_version {
             args.push("--llvm-version".to_owned());
             args.push(llvm_version.clone());
@@ -941,3 +952,130 @@ fn test_needs_target_std() {
     let config = cfg().target("x86_64-unknown-linux-gnu").build();
     assert!(!check_ignore(&config, "//@ needs-target-std"));
 }
+
+fn parse_edition_range(line: &str) -> Option<EditionRange> {
+    let config = cfg().build();
+    let line = super::DirectiveLine { line_number: 0, revision: None, raw_directive: line };
+
+    super::parse_edition_range(&config, &line, "tmp.rs".into())
+}
+
+#[test]
+fn test_parse_edition_range() {
+    assert_eq!(None, parse_edition_range("hello-world"));
+    assert_eq!(None, parse_edition_range("edition"));
+
+    assert_eq!(Some(EditionRange::Exact(2018.into())), parse_edition_range("edition: 2018"));
+    assert_eq!(Some(EditionRange::Exact(2021.into())), parse_edition_range("edition:2021"));
+    assert_eq!(Some(EditionRange::Exact(2024.into())), parse_edition_range("edition: 2024 "));
+    assert_eq!(Some(EditionRange::Exact(Edition::Future)), parse_edition_range("edition: future"));
+
+    assert_eq!(Some(EditionRange::RangeFrom(2018.into())), parse_edition_range("edition: 2018.."));
+    assert_eq!(Some(EditionRange::RangeFrom(2021.into())), parse_edition_range("edition:2021 .."));
+    assert_eq!(
+        Some(EditionRange::RangeFrom(2024.into())),
+        parse_edition_range("edition: 2024 .. ")
+    );
+    assert_eq!(
+        Some(EditionRange::RangeFrom(Edition::Future)),
+        parse_edition_range("edition: future.. ")
+    );
+
+    assert_eq!(
+        Some(EditionRange::Range { lower_bound: 2018.into(), upper_bound: 2024.into() }),
+        parse_edition_range("edition: 2018..2024")
+    );
+    assert_eq!(
+        Some(EditionRange::Range { lower_bound: 2015.into(), upper_bound: 2021.into() }),
+        parse_edition_range("edition:2015 .. 2021 ")
+    );
+    assert_eq!(
+        Some(EditionRange::Range { lower_bound: 2021.into(), upper_bound: 2027.into() }),
+        parse_edition_range("edition: 2021 .. 2027 ")
+    );
+    assert_eq!(
+        Some(EditionRange::Range { lower_bound: 2021.into(), upper_bound: Edition::Future }),
+        parse_edition_range("edition: 2021..future")
+    );
+}
+
+#[test]
+#[should_panic]
+fn test_parse_edition_range_empty() {
+    parse_edition_range("edition:");
+}
+
+#[test]
+#[should_panic]
+fn test_parse_edition_range_invalid_edition() {
+    parse_edition_range("edition: hello");
+}
+
+#[test]
+#[should_panic]
+fn test_parse_edition_range_double_dots() {
+    parse_edition_range("edition: ..");
+}
+
+#[test]
+#[should_panic]
+fn test_parse_edition_range_inverted_range() {
+    parse_edition_range("edition: 2021..2015");
+}
+
+#[test]
+#[should_panic]
+fn test_parse_edition_range_inverted_range_future() {
+    parse_edition_range("edition: future..2015");
+}
+
+#[test]
+#[should_panic]
+fn test_parse_edition_range_empty_range() {
+    parse_edition_range("edition: 2021..2021");
+}
+
+#[track_caller]
+fn assert_edition_to_test(
+    expected: impl Into<Edition>,
+    range: EditionRange,
+    default: Option<Edition>,
+) {
+    let mut cfg = cfg();
+    if let Some(default) = default {
+        cfg.edition(default);
+    }
+    assert_eq!(expected.into(), range.edition_to_test(cfg.build().edition));
+}
+
+#[test]
+fn test_edition_range_edition_to_test() {
+    let e2015 = parse_edition("2015");
+    let e2018 = parse_edition("2018");
+    let e2021 = parse_edition("2021");
+    let e2024 = parse_edition("2024");
+    let efuture = parse_edition("future");
+
+    let exact = EditionRange::Exact(2021.into());
+    assert_edition_to_test(2021, exact, None);
+    assert_edition_to_test(2021, exact, Some(e2018));
+    assert_edition_to_test(2021, exact, Some(efuture));
+
+    assert_edition_to_test(Edition::Future, EditionRange::Exact(Edition::Future), None);
+
+    let greater_equal_than = EditionRange::RangeFrom(2021.into());
+    assert_edition_to_test(2021, greater_equal_than, None);
+    assert_edition_to_test(2021, greater_equal_than, Some(e2015));
+    assert_edition_to_test(2021, greater_equal_than, Some(e2018));
+    assert_edition_to_test(2021, greater_equal_than, Some(e2021));
+    assert_edition_to_test(2024, greater_equal_than, Some(e2024));
+    assert_edition_to_test(Edition::Future, greater_equal_than, Some(efuture));
+
+    let range = EditionRange::Range { lower_bound: 2018.into(), upper_bound: 2024.into() };
+    assert_edition_to_test(2018, range, None);
+    assert_edition_to_test(2018, range, Some(e2015));
+    assert_edition_to_test(2018, range, Some(e2018));
+    assert_edition_to_test(2021, range, Some(e2021));
+    assert_edition_to_test(2018, range, Some(e2024));
+    assert_edition_to_test(2018, range, Some(efuture));
+}
diff --git a/src/tools/compiletest/src/edition.rs b/src/tools/compiletest/src/edition.rs
new file mode 100644
index 00000000000..36550cf5b2b
--- /dev/null
+++ b/src/tools/compiletest/src/edition.rs
@@ -0,0 +1,35 @@
+use crate::fatal;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum Edition {
+    // Note that the ordering here is load-bearing, as we want the future edition to be greater than
+    // any year-based edition.
+    Year(u32),
+    Future,
+}
+
+impl std::fmt::Display for Edition {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Edition::Year(year) => write!(f, "{year}"),
+            Edition::Future => f.write_str("future"),
+        }
+    }
+}
+
+impl From<u32> for Edition {
+    fn from(value: u32) -> Self {
+        Edition::Year(value)
+    }
+}
+
+pub fn parse_edition(mut input: &str) -> Edition {
+    input = input.trim();
+    if input == "future" {
+        Edition::Future
+    } else {
+        Edition::Year(input.parse().unwrap_or_else(|_| {
+            fatal!("`{input}` doesn't look like an edition");
+        }))
+    }
+}
diff --git a/src/tools/compiletest/src/lib.rs b/src/tools/compiletest/src/lib.rs
index 15e31dadf97..2d759279f34 100644
--- a/src/tools/compiletest/src/lib.rs
+++ b/src/tools/compiletest/src/lib.rs
@@ -7,6 +7,7 @@ pub mod common;
 mod debuggers;
 pub mod diagnostics;
 pub mod directives;
+pub mod edition;
 pub mod errors;
 mod executor;
 mod json;
@@ -39,6 +40,7 @@ use crate::common::{
     expected_output_path, output_base_dir, output_relative_path,
 };
 use crate::directives::DirectivesCache;
+use crate::edition::parse_edition;
 use crate::executor::{CollectedTest, ColorConfig};
 
 /// Creates the `Config` instance for this invocation of compiletest.
@@ -449,7 +451,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
         has_enzyme,
         channel: matches.opt_str("channel").unwrap(),
         git_hash: matches.opt_present("git-hash"),
-        edition: matches.opt_str("edition"),
+        edition: matches.opt_str("edition").as_deref().map(parse_edition),
 
         cc: matches.opt_str("cc").unwrap(),
         cxx: matches.opt_str("cxx").unwrap(),