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🍒 Add test suite coverage-map to test coverage mappings emitted by LLVM
We compile each test file to LLVM IR assembly, and then pass that IR to a dedicated program that can decode LLVM coverage maps and print them in a more human-readable format. We can then check that output against known-good snapshots. This test suite has some advantages over the existing `run-coverage` tests: - We can test coverage instrumentation without needing to run target binaries. - We can observe subtle improvements/regressions in the underlying coverage mappings that don't make a visible difference to coverage reports.
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11 files changed

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-2
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11 files changed

+293
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‎src/bootstrap/builder.rs‎

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@@ -726,6 +726,7 @@ impl<'a> Builder<'a> {
726726
test::Tidy,
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test::Ui,
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test::RunPassValgrind,
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test::CoverageMap,
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test::RunCoverage,
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test::MirOpt,
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test::Codegen,

‎src/bootstrap/test.rs‎

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@@ -1328,6 +1328,12 @@ host_test!(RunMakeFullDeps {
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default_test!(Assembly { path: "tests/assembly", mode: "assembly", suite: "assembly" });
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1331+
default_test!(CoverageMap {
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path: "tests/coverage-map",
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mode: "coverage-map",
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suite: "coverage-map"
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});
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host_test!(RunCoverage { path: "tests/run-coverage", mode: "run-coverage", suite: "run-coverage" });
13321338
host_test!(RunCoverageRustdoc {
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path: "tests/run-coverage-rustdoc",
@@ -1533,6 +1539,14 @@ note: if you're sure you want to do this, please open an issue as to why. In the
15331539
.arg(builder.ensure(tool::JsonDocLint { compiler: json_compiler, target }));
15341540
}
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1542+
if mode == "coverage-map" {
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let coverage_dump = builder.ensure(tool::CoverageDump {
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compiler: compiler.with_stage(0),
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target: compiler.host,
1546+
});
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cmd.arg("--coverage-dump-path").arg(coverage_dump);
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}
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15361550
if mode == "run-make" || mode == "run-coverage" {
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let rust_demangler = builder
15381552
.ensure(tool::RustDemangler {

‎src/tools/compiletest/src/common.rs‎

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@@ -66,6 +66,7 @@ string_enum! {
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JsDocTest => "js-doc-test",
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MirOpt => "mir-opt",
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Assembly => "assembly",
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CoverageMap => "coverage-map",
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RunCoverage => "run-coverage",
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}
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}
@@ -161,6 +162,9 @@ pub struct Config {
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/// The rust-demangler executable.
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pub rust_demangler_path: Option<PathBuf>,
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/// The coverage-dump executable.
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pub coverage_dump_path: Option<PathBuf>,
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/// The Python executable to use for LLDB and htmldocck.
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pub python: String,
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@@ -639,6 +643,7 @@ pub const UI_EXTENSIONS: &[&str] = &[
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UI_STDERR_32,
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UI_STDERR_16,
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UI_COVERAGE,
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UI_COVERAGE_MAP,
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];
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pub const UI_STDERR: &str = "stderr";
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pub const UI_STDOUT: &str = "stdout";
@@ -649,6 +654,7 @@ pub const UI_STDERR_64: &str = "64bit.stderr";
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pub const UI_STDERR_32: &str = "32bit.stderr";
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pub const UI_STDERR_16: &str = "16bit.stderr";
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pub const UI_COVERAGE: &str = "coverage";
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pub const UI_COVERAGE_MAP: &str = "cov-map";
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/// Absolute path to the directory where all output for all tests in the given
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/// `relative_dir` group should reside. Example:

‎src/tools/compiletest/src/lib.rs‎

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@@ -48,6 +48,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
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.reqopt("", "rustc-path", "path to rustc to use for compiling", "PATH")
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.optopt("", "rustdoc-path", "path to rustdoc to use for compiling", "PATH")
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.optopt("", "rust-demangler-path", "path to rust-demangler to use in tests", "PATH")
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.optopt("", "coverage-dump-path", "path to coverage-dump to use in tests", "PATH")
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.reqopt("", "python", "path to python to use for doc tests", "PATH")
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.optopt("", "jsondocck-path", "path to jsondocck to use for doc tests", "PATH")
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.optopt("", "jsondoclint-path", "path to jsondoclint to use for doc tests", "PATH")
@@ -218,6 +219,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
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rustc_path: opt_path(matches, "rustc-path"),
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rustdoc_path: matches.opt_str("rustdoc-path").map(PathBuf::from),
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rust_demangler_path: matches.opt_str("rust-demangler-path").map(PathBuf::from),
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coverage_dump_path: matches.opt_str("coverage-dump-path").map(PathBuf::from),
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python: matches.opt_str("python").unwrap(),
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jsondocck_path: matches.opt_str("jsondocck-path"),
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jsondoclint_path: matches.opt_str("jsondoclint-path"),

‎src/tools/compiletest/src/runtest.rs‎

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@@ -6,8 +6,8 @@ use crate::common::{Assembly, Incremental, JsDocTest, MirOpt, RunMake, RustdocJs
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use crate::common::{Codegen, CodegenUnits, DebugInfo, Debugger, Rustdoc};
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use crate::common::{CompareMode, FailMode, PassMode};
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use crate::common::{Config, TestPaths};
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use crate::common::{Pretty, RunCoverage, RunPassValgrind};
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use crate::common::{UI_COVERAGE, UI_RUN_STDERR, UI_RUN_STDOUT};
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use crate::common::{CoverageMap, Pretty, RunCoverage, RunPassValgrind};
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use crate::common::{UI_COVERAGE, UI_COVERAGE_MAP, UI_RUN_STDERR, UI_RUN_STDOUT};
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use crate::compute_diff::{write_diff, write_filtered_diff};
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use crate::errors::{self, Error, ErrorKind};
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use crate::header::TestProps;
@@ -254,6 +254,7 @@ impl<'test> TestCx<'test> {
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MirOpt => self.run_mir_opt_test(),
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Assembly => self.run_assembly_test(),
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JsDocTest => self.run_js_doc_test(),
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CoverageMap => self.run_coverage_map_test(),
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RunCoverage => self.run_coverage_test(),
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}
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}
@@ -467,6 +468,46 @@ impl<'test> TestCx<'test> {
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}
468469
}
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fn run_coverage_map_test(&self) {
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let Some(coverage_dump_path) = &self.config.coverage_dump_path else {
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self.fatal("missing --coverage-dump");
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};
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let proc_res = self.compile_test_and_save_ir();
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if !proc_res.status.success() {
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self.fatal_proc_rec("compilation failed!", &proc_res);
479+
}
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drop(proc_res);
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let llvm_ir_path = self.output_base_name().with_extension("ll");
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let mut dump_command = Command::new(coverage_dump_path);
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dump_command.arg(llvm_ir_path);
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let proc_res = self.run_command_to_procres(&mut dump_command);
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if !proc_res.status.success() {
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self.fatal_proc_rec("coverage-dump failed!", &proc_res);
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}
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let kind = UI_COVERAGE_MAP;
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let expected_coverage_dump = self.load_expected_output(kind);
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let actual_coverage_dump = self.normalize_output(&proc_res.stdout, &[]);
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let coverage_dump_errors = self.compare_output(
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kind,
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&actual_coverage_dump,
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&expected_coverage_dump,
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self.props.compare_output_lines_by_subset,
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);
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if coverage_dump_errors > 0 {
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self.fatal_proc_rec(
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&format!("{coverage_dump_errors} errors occurred comparing coverage output."),
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&proc_res,
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);
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}
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}
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fn run_coverage_test(&self) {
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let should_run = self.run_if_enabled();
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let proc_res = self.compile_test(should_run, Emit::None);
@@ -650,6 +691,10 @@ impl<'test> TestCx<'test> {
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let mut cmd = Command::new(tool_path);
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configure_cmd_fn(&mut cmd);
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self.run_command_to_procres(&mut cmd)
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}
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fn run_command_to_procres(&self, cmd: &mut Command) -> ProcRes {
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let output = cmd.output().unwrap_or_else(|_| panic!("failed to exec `{cmd:?}`"));
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let proc_res = ProcRes {
@@ -2399,6 +2444,12 @@ impl<'test> TestCx<'test> {
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24002445
rustc.arg(dir_opt);
24012446
}
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CoverageMap => {
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rustc.arg("-Cinstrument-coverage");
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// These tests only compile to MIR, so they don't need the
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// profiler runtime to be present.
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rustc.arg("-Zno-profiler-runtime");
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}
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RunCoverage => {
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rustc.arg("-Cinstrument-coverage");
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}

‎tests/coverage-map/if.cov-map‎

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@@ -0,0 +1,15 @@
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Function name: if::main
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Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 03, 01, 02, 0c, 05, 02, 0d, 02, 06, 02, 02, 06, 00, 07, 07, 01, 05, 01, 02]
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Number of files: 1
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- file 0 => global file 1
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Number of expressions: 2
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- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
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- expression 1 operands: lhs = Counter(1), rhs = Expression(0, Sub)
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Number of file 0 mappings: 4
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- Code(Counter(0)) at (prev + 3, 1) to (start + 2, 12)
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- Code(Counter(1)) at (prev + 2, 13) to (start + 2, 6)
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- Code(Expression(0, Sub)) at (prev + 2, 6) to (start + 0, 7)
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= (c0 - c1)
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- Code(Expression(1, Add)) at (prev + 1, 5) to (start + 1, 2)
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= (c1 + (c0 - c1))
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‎tests/coverage-map/if.rs‎

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// compile-flags: --edition=2021
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fn main() {
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let cond = std::env::args().len() == 1;
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if cond {
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println!("true");
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}
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println!("done");
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}

‎tests/coverage-map/long_and_wide.cov-map‎

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@@ -0,0 +1,32 @@
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Function name: long_and_wide::far_function
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Raw bytes (10): 0x[01, 01, 00, 01, 01, 96, 01, 01, 00, 15]
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Number of files: 1
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- file 0 => global file 1
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Number of expressions: 0
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Number of file 0 mappings: 1
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- Code(Counter(0)) at (prev + 150, 1) to (start + 0, 21)
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Function name: long_and_wide::long_function
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Raw bytes (10): 0x[01, 01, 00, 01, 01, 10, 01, 84, 01, 02]
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Number of files: 1
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- file 0 => global file 1
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Number of expressions: 0
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Number of file 0 mappings: 1
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- Code(Counter(0)) at (prev + 16, 1) to (start + 132, 2)
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Function name: long_and_wide::main
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Raw bytes (9): 0x[01, 01, 00, 01, 01, 07, 01, 04, 02]
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Number of files: 1
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- file 0 => global file 1
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Number of expressions: 0
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Number of file 0 mappings: 1
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- Code(Counter(0)) at (prev + 7, 1) to (start + 4, 2)
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Function name: long_and_wide::wide_function
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Raw bytes (10): 0x[01, 01, 00, 01, 01, 0e, 01, 00, 8b, 01]
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Number of files: 1
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- file 0 => global file 1
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Number of expressions: 0
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Number of file 0 mappings: 1
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- Code(Counter(0)) at (prev + 14, 1) to (start + 0, 139)
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‎tests/coverage-map/long_and_wide.rs‎

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// compile-flags: --edition=2021
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// ignore-tidy-linelength
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// This file deliberately contains line and column numbers larger than 127,
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// to verify that `coverage-dump`'s ULEB128 parser can handle them.
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fn main() {
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wide_function();
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long_function();
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far_function();
11+
}
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#[rustfmt::skip]
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fn wide_function() { /* */ (); }
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fn long_function() {
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}
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fn far_function() {}

‎tests/coverage-map/trivial.cov-map‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
1+
Function name: trivial::main
2+
Raw bytes (9): 0x[01, 01, 00, 01, 01, 03, 01, 00, 0d]
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Number of files: 1
4+
- file 0 => global file 1
5+
Number of expressions: 0
6+
Number of file 0 mappings: 1
7+
- Code(Counter(0)) at (prev + 3, 1) to (start + 0, 13)
8+

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