//! Some lints that are built in to the compiler.
//!
//! These are the built-in lints that are emitted direct in the main
//! compiler code, rather than using their own custom pass. Those
//! lints are all available in `rustc_lint::builtin`.

use crate::lint::{LintPass, LateLintPass, LintArray, FutureIncompatibleInfo};
use crate::middle::stability;
use crate::session::Session;
use errors::{Applicability, DiagnosticBuilder, pluralize};
use syntax::ast;
use syntax::edition::Edition;
use syntax::source_map::Span;
use syntax::symbol::Symbol;
use syntax::early_buffered_lints::{ILL_FORMED_ATTRIBUTE_INPUT, META_VARIABLE_MISUSE};
use rustc_session::declare_lint;

declare_lint! {
    pub EXCEEDING_BITSHIFTS,
    Deny,
    "shift exceeds the type's number of bits"
}

declare_lint! {
    pub CONST_ERR,
    Deny,
    "constant evaluation detected erroneous expression",
    report_in_external_macro
}

declare_lint! {
    pub UNUSED_IMPORTS,
    Warn,
    "imports that are never used"
}

declare_lint! {
    pub UNUSED_EXTERN_CRATES,
    Allow,
    "extern crates that are never used"
}

declare_lint! {
    pub UNUSED_QUALIFICATIONS,
    Allow,
    "detects unnecessarily qualified names"
}

declare_lint! {
    pub UNKNOWN_LINTS,
    Warn,
    "unrecognized lint attribute"
}

declare_lint! {
    pub UNUSED_VARIABLES,
    Warn,
    "detect variables which are not used in any way"
}

declare_lint! {
    pub UNUSED_ASSIGNMENTS,
    Warn,
    "detect assignments that will never be read"
}

declare_lint! {
    pub DEAD_CODE,
    Warn,
    "detect unused, unexported items"
}

declare_lint! {
    pub UNUSED_ATTRIBUTES,
    Warn,
    "detects attributes that were not used by the compiler"
}

declare_lint! {
    pub UNREACHABLE_CODE,
    Warn,
    "detects unreachable code paths",
    report_in_external_macro
}

declare_lint! {
    pub UNREACHABLE_PATTERNS,
    Warn,
    "detects unreachable patterns"
}

declare_lint! {
    pub OVERLAPPING_PATTERNS,
    Warn,
    "detects overlapping patterns"
}

declare_lint! {
    pub UNUSED_MACROS,
    Warn,
    "detects macros that were not used"
}

declare_lint! {
    pub WARNINGS,
    Warn,
    "mass-change the level for lints which produce warnings"
}

declare_lint! {
    pub UNUSED_FEATURES,
    Warn,
    "unused features found in crate-level `#[feature]` directives"
}

declare_lint! {
    pub STABLE_FEATURES,
    Warn,
    "stable features found in `#[feature]` directive"
}

declare_lint! {
    pub UNKNOWN_CRATE_TYPES,
    Deny,
    "unknown crate type found in `#[crate_type]` directive"
}

declare_lint! {
    pub TRIVIAL_CASTS,
    Allow,
    "detects trivial casts which could be removed"
}

declare_lint! {
    pub TRIVIAL_NUMERIC_CASTS,
    Allow,
    "detects trivial casts of numeric types which could be removed"
}

declare_lint! {
    pub PRIVATE_IN_PUBLIC,
    Warn,
    "detect private items in public interfaces not caught by the old implementation",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #34537 <https://github.com/rust-lang/rust/issues/34537>",
        edition: None,
    };
}

declare_lint! {
    pub EXPORTED_PRIVATE_DEPENDENCIES,
    Warn,
    "public interface leaks type from a private dependency"
}

declare_lint! {
    pub PUB_USE_OF_PRIVATE_EXTERN_CRATE,
    Deny,
    "detect public re-exports of private extern crates",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #34537 <https://github.com/rust-lang/rust/issues/34537>",
        edition: None,
    };
}

declare_lint! {
    pub INVALID_TYPE_PARAM_DEFAULT,
    Deny,
    "type parameter default erroneously allowed in invalid location",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #36887 <https://github.com/rust-lang/rust/issues/36887>",
        edition: None,
    };
}

declare_lint! {
    pub RENAMED_AND_REMOVED_LINTS,
    Warn,
    "lints that have been renamed or removed"
}

declare_lint! {
    pub SAFE_PACKED_BORROWS,
    Warn,
    "safe borrows of fields of packed structs were was erroneously allowed",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #46043 <https://github.com/rust-lang/rust/issues/46043>",
        edition: None,
    };
}

declare_lint! {
    pub PATTERNS_IN_FNS_WITHOUT_BODY,
    Deny,
    "patterns in functions without body were erroneously allowed",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #35203 <https://github.com/rust-lang/rust/issues/35203>",
        edition: None,
    };
}

declare_lint! {
    pub MISSING_FRAGMENT_SPECIFIER,
    Deny,
    "detects missing fragment specifiers in unused `macro_rules!` patterns",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #40107 <https://github.com/rust-lang/rust/issues/40107>",
        edition: None,
    };
}

declare_lint! {
    pub LATE_BOUND_LIFETIME_ARGUMENTS,
    Warn,
    "detects generic lifetime arguments in path segments with late bound lifetime parameters",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #42868 <https://github.com/rust-lang/rust/issues/42868>",
        edition: None,
    };
}

declare_lint! {
    pub ORDER_DEPENDENT_TRAIT_OBJECTS,
    Deny,
    "trait-object types were treated as different depending on marker-trait order",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #56484 <https://github.com/rust-lang/rust/issues/56484>",
        edition: None,
    };
}

declare_lint! {
    pub DEPRECATED,
    Warn,
    "detects use of deprecated items",
    report_in_external_macro
}

declare_lint! {
    pub UNUSED_UNSAFE,
    Warn,
    "unnecessary use of an `unsafe` block"
}

declare_lint! {
    pub UNUSED_MUT,
    Warn,
    "detect mut variables which don't need to be mutable"
}

declare_lint! {
    pub UNCONDITIONAL_RECURSION,
    Warn,
    "functions that cannot return without calling themselves"
}

declare_lint! {
    pub SINGLE_USE_LIFETIMES,
    Allow,
    "detects lifetime parameters that are only used once"
}

declare_lint! {
    pub UNUSED_LIFETIMES,
    Allow,
    "detects lifetime parameters that are never used"
}

declare_lint! {
    pub TYVAR_BEHIND_RAW_POINTER,
    Warn,
    "raw pointer to an inference variable",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #46906 <https://github.com/rust-lang/rust/issues/46906>",
        edition: Some(Edition::Edition2018),
    };
}

declare_lint! {
    pub ELIDED_LIFETIMES_IN_PATHS,
    Allow,
    "hidden lifetime parameters in types are deprecated"
}

declare_lint! {
    pub BARE_TRAIT_OBJECTS,
    Warn,
    "suggest using `dyn Trait` for trait objects"
}

declare_lint! {
    pub ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
    Allow,
    "fully qualified paths that start with a module name \
     instead of `crate`, `self`, or an extern crate name",
     @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #53130 <https://github.com/rust-lang/rust/issues/53130>",
        edition: Some(Edition::Edition2018),
     };
}

declare_lint! {
    pub ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
    Warn,
    "floating-point literals cannot be used in patterns",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #41620 <https://github.com/rust-lang/rust/issues/41620>",
        edition: None,
    };
}

declare_lint! {
    pub UNSTABLE_NAME_COLLISIONS,
    Warn,
    "detects name collision with an existing but unstable method",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #48919 <https://github.com/rust-lang/rust/issues/48919>",
        edition: None,
        // Note: this item represents future incompatibility of all unstable functions in the
        //       standard library, and thus should never be removed or changed to an error.
    };
}

declare_lint! {
    pub IRREFUTABLE_LET_PATTERNS,
    Warn,
    "detects irrefutable patterns in if-let and while-let statements"
}

declare_lint! {
    pub UNUSED_LABELS,
    Warn,
    "detects labels that are never used"
}

declare_lint! {
    pub INTRA_DOC_LINK_RESOLUTION_FAILURE,
    Warn,
    "failures in resolving intra-doc link targets"
}

declare_lint! {
    pub MISSING_DOC_CODE_EXAMPLES,
    Allow,
    "detects publicly-exported items without code samples in their documentation"
}

declare_lint! {
    pub PRIVATE_DOC_TESTS,
    Allow,
    "detects code samples in docs of private items not documented by rustdoc"
}

declare_lint! {
    pub WHERE_CLAUSES_OBJECT_SAFETY,
    Warn,
    "checks the object safety of where clauses",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #51443 <https://github.com/rust-lang/rust/issues/51443>",
        edition: None,
    };
}

declare_lint! {
    pub PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
    Warn,
    "detects proc macro derives using inaccessible names from parent modules",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #50504 <https://github.com/rust-lang/rust/issues/50504>",
        edition: None,
    };
}

declare_lint! {
    pub MACRO_USE_EXTERN_CRATE,
    Allow,
    "the `#[macro_use]` attribute is now deprecated in favor of using macros \
     via the module system"
}

declare_lint! {
    pub MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
    Deny,
    "macro-expanded `macro_export` macros from the current crate \
     cannot be referred to by absolute paths",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #52234 <https://github.com/rust-lang/rust/issues/52234>",
        edition: None,
    };
}

declare_lint! {
    pub EXPLICIT_OUTLIVES_REQUIREMENTS,
    Allow,
    "outlives requirements can be inferred"
}

declare_lint! {
    pub INDIRECT_STRUCTURAL_MATCH,
    // defaulting to allow until rust-lang/rust#62614 is fixed.
    Allow,
    "pattern with const indirectly referencing non-`#[structural_match]` type",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #62411 <https://github.com/rust-lang/rust/issues/62411>",
        edition: None,
    };
}

declare_lint! {
    pub DEPRECATED_IN_FUTURE,
    Allow,
    "detects use of items that will be deprecated in a future version",
    report_in_external_macro
}

declare_lint! {
    pub AMBIGUOUS_ASSOCIATED_ITEMS,
    Deny,
    "ambiguous associated items",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #57644 <https://github.com/rust-lang/rust/issues/57644>",
        edition: None,
    };
}

declare_lint! {
    pub MUTABLE_BORROW_RESERVATION_CONFLICT,
    Warn,
    "reservation of a two-phased borrow conflicts with other shared borrows",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #59159 <https://github.com/rust-lang/rust/issues/59159>",
        edition: None,
    };
}

declare_lint! {
    pub SOFT_UNSTABLE,
    Deny,
    "a feature gate that doesn't break dependent crates",
    @future_incompatible = FutureIncompatibleInfo {
        reference: "issue #64266 <https://github.com/rust-lang/rust/issues/64266>",
        edition: None,
    };
}

declare_lint_pass! {
    /// Does nothing as a lint pass, but registers some `Lint`s
    /// that are used by other parts of the compiler.
    HardwiredLints => [
        ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
        EXCEEDING_BITSHIFTS,
        UNUSED_IMPORTS,
        UNUSED_EXTERN_CRATES,
        UNUSED_QUALIFICATIONS,
        UNKNOWN_LINTS,
        UNUSED_VARIABLES,
        UNUSED_ASSIGNMENTS,
        DEAD_CODE,
        UNREACHABLE_CODE,
        UNREACHABLE_PATTERNS,
        OVERLAPPING_PATTERNS,
        UNUSED_MACROS,
        WARNINGS,
        UNUSED_FEATURES,
        STABLE_FEATURES,
        UNKNOWN_CRATE_TYPES,
        TRIVIAL_CASTS,
        TRIVIAL_NUMERIC_CASTS,
        PRIVATE_IN_PUBLIC,
        EXPORTED_PRIVATE_DEPENDENCIES,
        PUB_USE_OF_PRIVATE_EXTERN_CRATE,
        INVALID_TYPE_PARAM_DEFAULT,
        CONST_ERR,
        RENAMED_AND_REMOVED_LINTS,
        SAFE_PACKED_BORROWS,
        PATTERNS_IN_FNS_WITHOUT_BODY,
        MISSING_FRAGMENT_SPECIFIER,
        LATE_BOUND_LIFETIME_ARGUMENTS,
        ORDER_DEPENDENT_TRAIT_OBJECTS,
        DEPRECATED,
        UNUSED_UNSAFE,
        UNUSED_MUT,
        UNCONDITIONAL_RECURSION,
        SINGLE_USE_LIFETIMES,
        UNUSED_LIFETIMES,
        UNUSED_LABELS,
        TYVAR_BEHIND_RAW_POINTER,
        ELIDED_LIFETIMES_IN_PATHS,
        BARE_TRAIT_OBJECTS,
        ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
        UNSTABLE_NAME_COLLISIONS,
        IRREFUTABLE_LET_PATTERNS,
        INTRA_DOC_LINK_RESOLUTION_FAILURE,
        MISSING_DOC_CODE_EXAMPLES,
        PRIVATE_DOC_TESTS,
        WHERE_CLAUSES_OBJECT_SAFETY,
        PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
        MACRO_USE_EXTERN_CRATE,
        MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
        ILL_FORMED_ATTRIBUTE_INPUT,
        META_VARIABLE_MISUSE,
        DEPRECATED_IN_FUTURE,
        AMBIGUOUS_ASSOCIATED_ITEMS,
        MUTABLE_BORROW_RESERVATION_CONFLICT,
        INDIRECT_STRUCTURAL_MATCH,
        SOFT_UNSTABLE,
    ]
}

// this could be a closure, but then implementing derive traits
// becomes hacky (and it gets allocated)
#[derive(PartialEq, RustcEncodable, RustcDecodable, Debug)]
pub enum BuiltinLintDiagnostics {
    Normal,
    BareTraitObject(Span, /* is_global */ bool),
    AbsPathWithModule(Span),
    ProcMacroDeriveResolutionFallback(Span),
    MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
    ElidedLifetimesInPaths(usize, Span, bool, Span, String),
    UnknownCrateTypes(Span, String, String),
    UnusedImports(String, Vec<(Span, String)>),
    RedundantImport(Vec<(Span, bool)>, ast::Ident),
    DeprecatedMacro(Option<Symbol>, Span),
}

pub(crate) fn add_elided_lifetime_in_path_suggestion(
    sess: &Session,
    db: &mut DiagnosticBuilder<'_>,
    n: usize,
    path_span: Span,
    incl_angl_brckt: bool,
    insertion_span: Span,
    anon_lts: String,
) {
    let (replace_span, suggestion) = if incl_angl_brckt {
        (insertion_span, anon_lts)
    } else {
        // When possible, prefer a suggestion that replaces the whole
        // `Path<T>` expression with `Path<'_, T>`, rather than inserting `'_, `
        // at a point (which makes for an ugly/confusing label)
        if let Ok(snippet) = sess.source_map().span_to_snippet(path_span) {
            // But our spans can get out of whack due to macros; if the place we think
            // we want to insert `'_` isn't even within the path expression's span, we
            // should bail out of making any suggestion rather than panicking on a
            // subtract-with-overflow or string-slice-out-out-bounds (!)
            // FIXME: can we do better?
            if insertion_span.lo().0 < path_span.lo().0 {
                return;
            }
            let insertion_index = (insertion_span.lo().0 - path_span.lo().0) as usize;
            if insertion_index > snippet.len() {
                return;
            }
            let (before, after) = snippet.split_at(insertion_index);
            (path_span, format!("{}{}{}", before, anon_lts, after))
        } else {
            (insertion_span, anon_lts)
        }
    };
    db.span_suggestion(
        replace_span,
        &format!("indicate the anonymous lifetime{}", pluralize!(n)),
        suggestion,
        Applicability::MachineApplicable
    );
}

impl BuiltinLintDiagnostics {
    pub fn run(self, sess: &Session, db: &mut DiagnosticBuilder<'_>) {
        match self {
            BuiltinLintDiagnostics::Normal => (),
            BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
                let (sugg, app) = match sess.source_map().span_to_snippet(span) {
                    Ok(ref s) if is_global => (format!("dyn ({})", s),
                                               Applicability::MachineApplicable),
                    Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
                    Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders)
                };
                db.span_suggestion(span, "use `dyn`", sugg, app);
            }
            BuiltinLintDiagnostics::AbsPathWithModule(span) => {
                let (sugg, app) = match sess.source_map().span_to_snippet(span) {
                    Ok(ref s) => {
                        // FIXME(Manishearth) ideally the emitting code
                        // can tell us whether or not this is global
                        let opt_colon = if s.trim_start().starts_with("::") {
                            ""
                        } else {
                            "::"
                        };

                        (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
                    }
                    Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders)
                };
                db.span_suggestion(span, "use `crate`", sugg, app);
            }
            BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
                db.span_label(span, "names from parent modules are not \
                                     accessible without an explicit import");
            }
            BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def) => {
                db.span_note(span_def, "the macro is defined here");
            }
            BuiltinLintDiagnostics::ElidedLifetimesInPaths(
                n, path_span, incl_angl_brckt, insertion_span, anon_lts
            ) => {
                add_elided_lifetime_in_path_suggestion(
                    sess,
                    db,
                    n,
                    path_span,
                    incl_angl_brckt,
                    insertion_span,
                    anon_lts,
                );
            }
            BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
                db.span_suggestion(span, &note, sugg, Applicability::MaybeIncorrect);
            }
            BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
                if !replaces.is_empty() {
                    db.tool_only_multipart_suggestion(
                        &message,
                        replaces,
                        Applicability::MachineApplicable,
                    );
                }
            }
            BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
                for (span, is_imported) in spans {
                    let introduced = if is_imported { "imported" } else { "defined" };
                    db.span_label(
                        span,
                        format!("the item `{}` is already {} here", ident, introduced)
                    );
                }
            }
            BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) =>
                stability::deprecation_suggestion(db, suggestion, span),
        }
    }
}

impl<'a, 'tcx> LateLintPass<'a, 'tcx> for HardwiredLints {}