From b392a732d31f9be028e4b2dcf4752c5e4c7a9880 Mon Sep 17 00:00:00 2001
From: Florian Diebold <flodiebold@gmail.com>
Date: Wed, 1 Apr 2020 20:27:47 +0200
Subject: [PATCH] Add inference for literal and range patterns

---
 crates/ra_hir_ty/src/infer/pat.rs        | 11 ++-
 crates/ra_hir_ty/src/tests/coercion.rs   |  6 ++
 crates/ra_hir_ty/src/tests/patterns.rs   | 85 ++++++++++++++++++++++++
 crates/ra_hir_ty/src/tests/regression.rs |  3 +-
 crates/ra_hir_ty/src/tests/simple.rs     |  2 +
 5 files changed, 104 insertions(+), 3 deletions(-)

diff --git a/crates/ra_hir_ty/src/infer/pat.rs b/crates/ra_hir_ty/src/infer/pat.rs
index baed6225b0..86acd27f8d 100644
--- a/crates/ra_hir_ty/src/infer/pat.rs
+++ b/crates/ra_hir_ty/src/infer/pat.rs
@@ -11,7 +11,7 @@ use hir_def::{
 use hir_expand::name::Name;
 use test_utils::tested_by;
 
-use super::{BindingMode, InferenceContext};
+use super::{BindingMode, Expectation, InferenceContext};
 use crate::{utils::variant_data, Substs, Ty, TypeCtor};
 
 impl<'a> InferenceContext<'a> {
@@ -198,7 +198,14 @@ impl<'a> InferenceContext<'a> {
 
                 Ty::apply_one(container_ty, elem_ty)
             }
-            _ => Ty::Unknown,
+            Pat::Wild => expected.clone(),
+            Pat::Range { start, end } => {
+                let start_ty = self.infer_expr(*start, &Expectation::has_type(expected.clone()));
+                let end_ty = self.infer_expr(*end, &Expectation::has_type(start_ty));
+                end_ty
+            }
+            Pat::Lit(expr) => self.infer_expr(*expr, &Expectation::has_type(expected.clone())),
+            Pat::Missing => Ty::Unknown,
         };
         // use a new type variable if we got Ty::Unknown here
         let ty = self.insert_type_vars_shallow(ty);
diff --git a/crates/ra_hir_ty/src/tests/coercion.rs b/crates/ra_hir_ty/src/tests/coercion.rs
index 1e303f5ce4..3e3d55c041 100644
--- a/crates/ra_hir_ty/src/tests/coercion.rs
+++ b/crates/ra_hir_ty/src/tests/coercion.rs
@@ -275,12 +275,14 @@ fn test(i: i32) {
     [70; 147) 'match ...     }': &[i32]
     [76; 77) 'i': i32
     [88; 89) '2': i32
+    [88; 89) '2': i32
     [93; 96) 'foo': fn foo<i32>(&[i32]) -> &[i32]
     [93; 102) 'foo(&[2])': &[i32]
     [97; 101) '&[2]': &[i32; _]
     [98; 101) '[2]': [i32; _]
     [99; 100) '2': i32
     [112; 113) '1': i32
+    [112; 113) '1': i32
     [117; 121) '&[1]': &[i32; _]
     [118; 121) '[1]': [i32; _]
     [119; 120) '1': i32
@@ -316,10 +318,12 @@ fn test(i: i32) {
     [70; 147) 'match ...     }': &[i32]
     [76; 77) 'i': i32
     [88; 89) '1': i32
+    [88; 89) '1': i32
     [93; 97) '&[1]': &[i32; _]
     [94; 97) '[1]': [i32; _]
     [95; 96) '1': i32
     [107; 108) '2': i32
+    [107; 108) '2': i32
     [112; 115) 'foo': fn foo<i32>(&[i32]) -> &[i32]
     [112; 121) 'foo(&[2])': &[i32]
     [116; 120) '&[2]': &[i32; _]
@@ -357,9 +361,11 @@ fn test() {
     [45; 142) 'match ...     }': *const i32
     [51; 52) '1': i32
     [63; 64) '1': i32
+    [63; 64) '1': i32
     [68; 69) 't': &mut i32
     [68; 81) 't as *mut i32': *mut i32
     [91; 92) '2': i32
+    [91; 92) '2': i32
     [96; 97) 't': &mut i32
     [96; 105) 't as &i32': &i32
     [115; 116) '_': i32
diff --git a/crates/ra_hir_ty/src/tests/patterns.rs b/crates/ra_hir_ty/src/tests/patterns.rs
index 76aa320246..6e5d2247ca 100644
--- a/crates/ra_hir_ty/src/tests/patterns.rs
+++ b/crates/ra_hir_ty/src/tests/patterns.rs
@@ -81,6 +81,90 @@ fn test(x: &i32) {
     );
 }
 
+#[test]
+fn infer_literal_pattern() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn any<T>() -> T { loop {} }
+fn test(x: &i32) {
+    if let "foo" = any() {}
+    if let 1 = any() {}
+    if let 1u32 = any() {}
+    if let 1f32 = any() {}
+    if let 1.0 = any() {}
+    if let true = any() {}
+}
+"#, true),
+        @r###"
+    [18; 29) '{ loop {} }': T
+    [20; 27) 'loop {}': !
+    [25; 27) '{}': ()
+    [38; 39) 'x': &i32
+    [47; 209) '{     ...) {} }': ()
+    [53; 76) 'if let...y() {}': ()
+    [60; 65) '"foo"': &str
+    [60; 65) '"foo"': &str
+    [68; 71) 'any': fn any<&str>() -> &str
+    [68; 73) 'any()': &str
+    [74; 76) '{}': ()
+    [81; 100) 'if let...y() {}': ()
+    [88; 89) '1': i32
+    [88; 89) '1': i32
+    [92; 95) 'any': fn any<i32>() -> i32
+    [92; 97) 'any()': i32
+    [98; 100) '{}': ()
+    [105; 127) 'if let...y() {}': ()
+    [112; 116) '1u32': u32
+    [112; 116) '1u32': u32
+    [119; 122) 'any': fn any<u32>() -> u32
+    [119; 124) 'any()': u32
+    [125; 127) '{}': ()
+    [132; 154) 'if let...y() {}': ()
+    [139; 143) '1f32': f32
+    [139; 143) '1f32': f32
+    [146; 149) 'any': fn any<f32>() -> f32
+    [146; 151) 'any()': f32
+    [152; 154) '{}': ()
+    [159; 180) 'if let...y() {}': ()
+    [166; 169) '1.0': f64
+    [166; 169) '1.0': f64
+    [172; 175) 'any': fn any<f64>() -> f64
+    [172; 177) 'any()': f64
+    [178; 180) '{}': ()
+    [185; 207) 'if let...y() {}': ()
+    [192; 196) 'true': bool
+    [192; 196) 'true': bool
+    [199; 202) 'any': fn any<bool>() -> bool
+    [199; 204) 'any()': bool
+    [205; 207) '{}': ()
+    "###
+    );
+}
+
+#[test]
+fn infer_range_pattern() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn test(x: &i32) {
+    if let 1..76 = 2u32 {}
+    if let 1..=76 = 2u32 {}
+}
+"#, true),
+        @r###"
+    [9; 10) 'x': &i32
+    [18; 76) '{     ...2 {} }': ()
+    [24; 46) 'if let...u32 {}': ()
+    [31; 36) '1..76': u32
+    [39; 43) '2u32': u32
+    [44; 46) '{}': ()
+    [51; 74) 'if let...u32 {}': ()
+    [58; 64) '1..=76': u32
+    [67; 71) '2u32': u32
+    [72; 74) '{}': ()
+    "###
+    );
+}
+
 #[test]
 fn infer_pattern_match_ergonomics() {
     assert_snapshot!(
@@ -212,6 +296,7 @@ fn test() {
     [59; 62) 'arr': [f64; _]
     [73; 81) '[1.0, a]': [f64; _]
     [74; 77) '1.0': f64
+    [74; 77) '1.0': f64
     [79; 80) 'a': f64
     [85; 111) '{     ...     }': ()
     [99; 100) 'a': f64
diff --git a/crates/ra_hir_ty/src/tests/regression.rs b/crates/ra_hir_ty/src/tests/regression.rs
index a02e3ee051..2ee9b8f101 100644
--- a/crates/ra_hir_ty/src/tests/regression.rs
+++ b/crates/ra_hir_ty/src/tests/regression.rs
@@ -206,7 +206,8 @@ pub fn compute() {
     [24; 106) 'match ...     }': ()
     [30; 37) 'nope!()': {unknown}
     [48; 94) 'SizeSk...tail }': {unknown}
-    [82; 86) 'true': {unknown}
+    [82; 86) 'true': bool
+    [82; 86) 'true': bool
     [88; 92) 'tail': {unknown}
     [98; 100) '{}': ()
     "###
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index c140bd5130..a600b947d0 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -948,6 +948,7 @@ fn foo() {
     [165; 247) 'match ...     }': i32
     [171; 175) 'true': bool
     [186; 190) 'true': bool
+    [186; 190) 'true': bool
     [194; 195) '3': i32
     [205; 206) '_': bool
     [210; 241) '{     ...     }': !
@@ -956,6 +957,7 @@ fn foo() {
     [263; 320) 'match ...     }': i32
     [269; 273) 'true': bool
     [284; 288) 'true': bool
+    [284; 288) 'true': bool
     [292; 293) '4': i32
     [303; 304) '_': bool
     [308; 314) 'return': !