fix: large_stack_frames FP on compiler generated targets

Author: profetia

CHANGELOG.md

@@ -6643,6 +6643,8 @@ Released 2018-09-13
 [`single-char-binding-names-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#single-char-binding-names-threshold
 [`source-item-ordering`]: https://doc.rust-lang.org/clippy/lint_configuration.html#source-item-ordering
 [`stack-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#stack-size-threshold
+[`lint-macro-generated-functions`]: https://doc.rust-lang.org/clippy/lint_configuration.html#lint-macro-generated-functions
+[`lint-inside-tests`]: https://doc.rust-lang.org/clippy/lint_configuration.html#lint-inside-tests
 [`standard-macro-braces`]: https://doc.rust-lang.org/clippy/lint_configuration.html#standard-macro-braces
 [`struct-field-name-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#struct-field-name-threshold
 [`suppress-restriction-lint-in-const`]: https://doc.rust-lang.org/clippy/lint_configuration.html#suppress-restriction-lint-in-const

book/src/lint_configuration.md

@@ -966,6 +966,26 @@ The maximum allowed stack size for functions in bytes
 * [`large_stack_frames`](https://rust-lang.github.io/rust-clippy/master/index.html#large_stack_frames)
 
 
+## `lint-macro-generated-functions`
+Whether functions generated by macros should be checked.
+
+**Default Value:** `true`
+
+---
+**Affected lints:**
+* [`large_stack_frames`](https://rust-lang.github.io/rust-clippy/master/index.html#large_stack_frames)
+
+
+## `lint-inside-tests`
+Whether functions inside `#[cfg(test)]` modules or test functions should be checked.
+
+**Default Value:** `false`
+
+---
+**Affected lints:**
+* [`large_stack_frames`](https://rust-lang.github.io/rust-clippy/master/index.html#large_stack_frames)
+
+
 ## `standard-macro-braces`
 Enforce the named macros always use the braces specified.
 

clippy_config/src/conf.rs

@@ -672,6 +672,12 @@ define_Conf! {
     /// Use the `check-inconsistent-struct-field-initializers` configuration instead.
     #[conf_deprecated("Please use `check-inconsistent-struct-field-initializers` instead", check_inconsistent_struct_field_initializers)]
     lint_inconsistent_struct_field_initializers: bool = false,
+    /// Whether functions inside `#[cfg(test)]` modules or test functions should be checked.
+    #[lints(large_stack_frames)]
+    lint_inside_tests: bool = false,
+    /// Whether functions generated by macros should be checked.
+    #[lints(large_stack_frames)]
+    lint_macro_generated_functions: bool = false,
     /// The lower bound for linting decimal literals
     #[lints(decimal_literal_representation)]
     literal_representation_threshold: u64 = 16384,

clippy_lints/src/large_stack_frames.rs

@@ -2,8 +2,8 @@ use std::{fmt, ops};
 
 use clippy_config::Conf;
 use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::fn_has_unsatisfiable_preds;
 use clippy_utils::source::SpanRangeExt;
+use clippy_utils::{fn_has_unsatisfiable_preds, is_in_test};
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{Body, FnDecl};
@@ -83,12 +83,16 @@ declare_clippy_lint! {
 
 pub struct LargeStackFrames {
     maximum_allowed_size: u64,
+    lint_macro_generated_functions: bool,
+    lint_inside_tests: bool,
 }
 
 impl LargeStackFrames {
     pub fn new(conf: &'static Conf) -> Self {
         Self {
             maximum_allowed_size: conf.stack_size_threshold,
+            lint_macro_generated_functions: conf.lint_macro_generated_functions,
+            lint_inside_tests: conf.lint_inside_tests,
         }
     }
 }
@@ -170,16 +174,45 @@ impl<'tcx> LateLintPass<'tcx> for LargeStackFrames {
                 FnKind::Closure => entire_fn_span,
             };
 
+            // Don't lint inside tests if configured to not do so.
+            if !self.lint_inside_tests && is_in_test(cx.tcx, cx.tcx.local_def_id_to_hir_id(local_def_id)) {
+                return;
+            }
+
+            let mut is_from_expansion = false;
+            if fn_span.from_expansion() {
+                // Don't lint functions that are generated by special compiling targets, like `--test`.
+                if fn_span.is_dummy() && fn_span.source_callsite().is_dummy() {
+                    return;
+                }
+
+                // Don't lint functions generated by macros if configured to not do so.
+                if !self.lint_macro_generated_functions {
+                    return;
+                }
+
+                is_from_expansion = true;
+            }
+
             span_lint_and_then(
                 cx,
                 LARGE_STACK_FRAMES,
-                fn_span,
-                format!("this function may allocate {frame_size} on the stack"),
+                fn_span.source_callsite(),
+                if is_from_expansion {
+                    "function generated by this macro may allocate a lot of stack space".to_owned()
+                } else {
+                    format!("this function may allocate {frame_size} on the stack")
+                },
                 |diag| {
+                    if is_from_expansion {
+                        diag.note(format!("this function has a stack frame size of {frame_size}"));
+                    }
                     // Point out the largest individual contribution to this size, because
                     // it is the most likely to be unintentionally large.
-                    if let Some((local, size)) = sizes_of_locals().max_by_key(|&(_, size)| size) {
-                        let local_span: Span = local.source_info.span;
+                    else if let Some((local, size)) = sizes_of_locals().max_by_key(|&(_, size)| size)
+                        && let local_span = local.source_info.span
+                        && !local_span.from_expansion()
+                    {
                         let size = Space::Used(size); // pluralizes for us
                         let ty = local.ty;
 

tests/ui-toml/large_stack_frames_for_macro_generated_fns/clippy.toml

@@ -0,0 +1,2 @@
+stack-size-threshold = 0
+lint-macro-generated-functions = true

tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs

@@ -0,0 +1,38 @@
+//@ normalize-stderr-test: "\b10000(08|16|32)\b" -> "100$$PTR"
+//@ normalize-stderr-test: "\b2500(060|120)\b" -> "250$$PTR"
+
+#![warn(clippy::large_stack_frames)]
+
+extern crate serde;
+
+use serde::{Deserialize, Serialize};
+
+struct ArrayDefault<const N: usize>([u8; N]);
+
+macro_rules! mac {
+    ($name:ident) => {
+        fn foo(x: ArrayDefault<1_000_000>) {
+            let $name = 1;
+            println!("macro_name called");
+        }
+    };
+}
+
+mac!(something);
+//~^ large_stack_frames
+
+#[derive(Deserialize, Serialize)]
+//~^ large_stack_frames
+//~| large_stack_frames
+//~| large_stack_frames
+//~| large_stack_frames
+//~| large_stack_frames
+//~| large_stack_frames
+//~| large_stack_frames
+//~| large_stack_frames
+
+struct S {
+    a: [u128; 31],
+}
+
+fn main() {}

tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.stderr

@@ -0,0 +1,87 @@
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:21:1
+   |
+LL | mac!(something);
+   | ^^^^^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 1000092 bytes
+   = note: 1000092 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+   = note: allocating large amounts of stack space can overflow the stack and cause the program to abort
+   = note: `-D clippy::large-stack-frames` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::large_stack_frames)]`
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:10
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |          ^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 57 bytes
+   = note: 57 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:10
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |          ^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 10 bytes
+   = note: 10 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:10
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |          ^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 19 bytes
+   = note: 19 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:10
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |          ^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 35 bytes
+   = note: 35 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:10
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |          ^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 57 bytes
+   = note: 57 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:10
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |          ^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 3137 bytes
+   = note: 3137 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:10
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |          ^^^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 4798 bytes
+   = note: 4798 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+
+error: function generated by this macro may allocate a lot of stack space
+  --> tests/ui-toml/large_stack_frames_for_macro_generated_fns/large_stack_frames.rs:24:23
+   |
+LL | #[derive(Deserialize, Serialize)]
+   |                       ^^^^^^^^^
+   |
+   = note: this function has a stack frame size of 170 bytes
+   = note: 170 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+
+error: aborting due to 9 previous errors
+

tests/ui-toml/large_stack_frames_for_special_targets/clippy.toml

@@ -0,0 +1,2 @@
+stack-size-threshold = 0
+lint-inside-tests = true

tests/ui-toml/large_stack_frames_for_special_targets/large_stack_frames.rs

@@ -0,0 +1,13 @@
+// This test checks if `clippy::large_stack_frames` is working correctly when encountering functions
+// generated by special compiling targets like `--test`.
+//@compile-flags: --test
+//@check-pass
+
+#![warn(clippy::large_stack_frames)]
+
+#[cfg(test)]
+#[allow(clippy::large_stack_frames)]
+mod test {
+    #[test]
+    fn main_test() {}
+}

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -50,6 +50,8 @@ error: error reading Clippy's configuration file: unknown field `foobar`, expect
            ignore-interior-mutability
            large-error-threshold
            lint-commented-code
+           lint-inside-tests
+           lint-macro-generated-functions
            literal-representation-threshold
            matches-for-let-else
            max-fn-params-bools
@@ -144,6 +146,8 @@ error: error reading Clippy's configuration file: unknown field `barfoo`, expect
            ignore-interior-mutability
            large-error-threshold
            lint-commented-code
+           lint-inside-tests
+           lint-macro-generated-functions
            literal-representation-threshold
            matches-for-let-else
            max-fn-params-bools
@@ -238,6 +242,8 @@ error: error reading Clippy's configuration file: unknown field `allow_mixed_uni
            ignore-interior-mutability
            large-error-threshold
            lint-commented-code
+           lint-inside-tests
+           lint-macro-generated-functions
            literal-representation-threshold
            matches-for-let-else
            max-fn-params-bools