compiletest: Add LineNumber newtype to avoid +1 magic here and there

Start small. If it works well we can increase usage bit by bit as time
passes.

Author: Enselic

src/tools/compiletest/src/directives.rs

@@ -33,6 +33,36 @@ mod needs;
 #[cfg(test)]
 mod tests;
 
+/// A line number in a file. Internally the first line has index 1.
+/// If it is 0 it means "no specific line" (used e.g. for implied directives).
+/// When displayed, the first line is 1.
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub(crate) struct LineNumber(usize);
+
+impl LineNumber {
+    /// Create a LineNumber from a zero-based line index. I.e. if `zero_based`
+    /// is `0` it means "the first line".
+    pub(crate) fn from_zero_based(zero_based: usize) -> Self {
+        // Ensure to panic on overflow.
+        LineNumber(zero_based.strict_add(1))
+    }
+
+    pub(crate) fn from_one_based(one_based: usize) -> LineNumber {
+        assert!(one_based > 0);
+        LineNumber(one_based)
+    }
+
+    pub(crate) fn none() -> LineNumber {
+        LineNumber(0)
+    }
+}
+
+impl std::fmt::Display for LineNumber {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
 pub struct DirectivesCache {
     /// "Conditions" used by `ignore-*` and `only-*` directives, prepared in
     /// advance so that they don't have to be evaluated repeatedly.
@@ -591,7 +621,7 @@ fn iter_directives(
         ];
         // Process the extra implied directives, with a dummy line number of 0.
         for directive_str in extra_directives {
-            let directive_line = line_directive(testfile, 0, directive_str)
+            let directive_line = line_directive(testfile, LineNumber::none(), directive_str)
                 .unwrap_or_else(|| panic!("bad extra-directive line: {directive_str:?}"));
             it(&directive_line);
         }

src/tools/compiletest/src/directives/file.rs

@@ -1,5 +1,6 @@
 use camino::Utf8Path;
 
+use crate::directives::LineNumber;
 use crate::directives::line::{DirectiveLine, line_directive};
 
 pub(crate) struct FileDirectives<'a> {
@@ -12,6 +13,8 @@ impl<'a> FileDirectives<'a> {
         let mut lines = vec![];
 
         for (line_number, ln) in (1..).zip(file_contents.lines()) {
+            let line_number = LineNumber::from_one_based(line_number);
+
             let ln = ln.trim();
 
             if let Some(directive_line) = line_directive(path, line_number, ln) {

src/tools/compiletest/src/directives/line.rs

@@ -2,13 +2,15 @@ use std::fmt;
 
 use camino::Utf8Path;
 
+use crate::directives::LineNumber;
+
 const COMPILETEST_DIRECTIVE_PREFIX: &str = "//@";
 
 /// If the given line begins with the appropriate comment prefix for a directive,
 /// returns a struct containing various parts of the directive.
 pub(crate) fn line_directive<'a>(
     file_path: &'a Utf8Path,
-    line_number: usize,
+    line_number: LineNumber,
     original_line: &'a str,
 ) -> Option<DirectiveLine<'a>> {
     // Ignore lines that don't start with the comment prefix.
@@ -60,7 +62,7 @@ pub(crate) struct DirectiveLine<'a> {
     /// Mostly used for diagnostics, but some directives (e.g. `//@ pp-exact`)
     /// also use it to compute a value based on the filename.
     pub(crate) file_path: &'a Utf8Path,
-    pub(crate) line_number: usize,
+    pub(crate) line_number: LineNumber,
 
     /// Some test directives start with a revision name in square brackets
     /// (e.g. `[foo]`), and only apply to that revision of the test.

src/tools/compiletest/src/directives/tests.rs

@@ -6,8 +6,8 @@ use semver::Version;
 use crate::common::{Config, Debugger, TestMode};
 use crate::directives::{
     self, AuxProps, DIRECTIVE_HANDLERS_MAP, DirectivesCache, EarlyProps, Edition, EditionRange,
-    FileDirectives, KNOWN_DIRECTIVE_NAMES_SET, extract_llvm_version, extract_version_range,
-    line_directive, parse_edition, parse_normalize_rule,
+    FileDirectives, KNOWN_DIRECTIVE_NAMES_SET, LineNumber, extract_llvm_version,
+    extract_version_range, line_directive, parse_edition, parse_normalize_rule,
 };
 use crate::executor::{CollectedTestDesc, ShouldFail};
 
@@ -1000,7 +1000,8 @@ fn parse_edition_range(line: &str) -> Option<EditionRange> {
     let config = cfg().build();
 
     let line_with_comment = format!("//@ {line}");
-    let line = line_directive(Utf8Path::new("tmp.rs"), 0, &line_with_comment).unwrap();
+    let line =
+        line_directive(Utf8Path::new("tmp.rs"), LineNumber::none(), &line_with_comment).unwrap();
 
     super::parse_edition_range(&config, &line)
 }

src/tools/compiletest/src/runtest/debugger.rs

@@ -4,16 +4,17 @@ use std::io::{BufRead, BufReader};
 
 use camino::{Utf8Path, Utf8PathBuf};
 
+use crate::directives::LineNumber;
 use crate::runtest::ProcRes;
 
 /// Representation of information to invoke a debugger and check its output
 pub(super) struct DebuggerCommands {
     /// Commands for the debuuger
     pub commands: Vec<String>,
     /// Lines to insert breakpoints at
-    pub breakpoint_lines: Vec<usize>,
+    pub breakpoint_lines: Vec<LineNumber>,
     /// Contains the source line number to check and the line itself
-    check_lines: Vec<(usize, String)>,
+    check_lines: Vec<(LineNumber, String)>,
     /// Source file name
     file: Utf8PathBuf,
 }
@@ -26,15 +27,14 @@ impl DebuggerCommands {
         let mut breakpoint_lines = vec![];
         let mut commands = vec![];
         let mut check_lines = vec![];
-        let mut counter = 0;
         let reader = BufReader::new(File::open(file.as_std_path()).unwrap());
         for (line_no, line) in reader.lines().enumerate() {
-            counter += 1;
             let line = line.map_err(|e| format!("Error while parsing debugger commands: {}", e))?;
+            let line_number = LineNumber::from_zero_based(line_no);
 
             // Breakpoints appear on lines with actual code, typically at the end of the line.
             if line.contains("#break") {
-                breakpoint_lines.push(counter);
+                breakpoint_lines.push(line_number);
                 continue;
             }
 
@@ -46,7 +46,7 @@ impl DebuggerCommands {
                 commands.push(command);
             }
             if let Some(pattern) = parse_name_value(&line, &check_directive) {
-                check_lines.push((line_no, pattern));
+                check_lines.push((line_number, pattern));
             }
         }
 
@@ -88,15 +88,14 @@ impl DebuggerCommands {
             );
 
             for (src_lineno, err_line) in missing {
-                write!(msg, "\n    ({fname}:{num}) `{err_line}`", num = src_lineno + 1).unwrap();
+                write!(msg, "\n    ({fname}:{src_lineno}) `{err_line}`").unwrap();
             }
 
             if !found.is_empty() {
                 let init = "\nthe following subset of check directive(s) was found successfully:";
                 msg.push_str(init);
                 for (src_lineno, found_line) in found {
-                    write!(msg, "\n    ({fname}:{num}) `{found_line}`", num = src_lineno + 1)
-                        .unwrap();
+                    write!(msg, "\n    ({fname}:{src_lineno}) `{found_line}`").unwrap();
                 }
             }