tint/transform: Handle 'const' for Unshadow.

Bug: tint:1580
Change-Id: I0af473ac13abde1f1890851aeb92812be6a52933
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/94682
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/tint/transform/unshadow.cc

@@ -63,6 +63,9 @@ struct Unshadow::State {
                 [&](const ast::Let*) {
                     return ctx.dst->Let(source, symbol, type, constructor, attributes);
                 },
+                [&](const ast::Const*) {
+                    return ctx.dst->Const(source, symbol, type, constructor, attributes);
+                },
                 [&](const ast::Parameter*) {
                     return ctx.dst->Param(source, symbol, type, attributes);
                 },

src/tint/transform/unshadow_test.cc

@@ -34,14 +34,16 @@ TEST_F(UnshadowTest, Noop) {
     auto* src = R"(
 var<private> a : i32;
 
-let b : i32 = 1;
+const b : i32 = 1;
 
 fn F(c : i32) {
   var d : i32;
   let e : i32 = 1;
+  const f : i32 = 2;
   {
-    var f : i32;
-    let g : i32 = 1;
+    var g : i32;
+    let h : i32 = 1;
+    const i : i32 = 2;
   }
 }
 )";
@@ -64,6 +66,10 @@ fn X() {
 fn Y() {
   let a = true;
 }
+
+fn Z() {
+  const a = true;
+}
 )";
 
     auto* expect = R"(
@@ -76,6 +82,10 @@ fn X() {
 fn Y() {
   let a_2 = true;
 }
+
+fn Z() {
+  const a_3 = true;
+}
 )";
 
     auto got = Run<Unshadow>(src);
@@ -93,6 +103,10 @@ fn Y() {
   let a = true;
 }
 
+fn Z() {
+  const a = true;
+}
+
 type a = i32;
 )";
 
@@ -105,6 +119,10 @@ fn Y() {
   let a_2 = true;
 }
 
+fn Z() {
+  const a_3 = true;
+}
+
 type a = i32;
 )";
 
@@ -126,6 +144,10 @@ fn X() {
 fn Y() {
   let a = false;
 }
+
+fn Z() {
+  const a = false;
+}
 )";
 
     auto* expect = R"(
@@ -140,6 +162,10 @@ fn X() {
 fn Y() {
   let a_2 = false;
 }
+
+fn Z() {
+  const a_3 = false;
+}
 )";
 
     auto got = Run<Unshadow>(src);
@@ -157,6 +183,10 @@ fn Y() {
   let a = false;
 }
 
+fn Z() {
+  const a = false;
+}
+
 struct a {
   m : i32,
 };
@@ -172,6 +202,10 @@ fn Y() {
   let a_2 = false;
 }
 
+fn Z() {
+  const a_3 = false;
+}
+
 struct a {
   m : i32,
 }
@@ -187,11 +221,19 @@ TEST_F(UnshadowTest, LocalShadowsFunction) {
 fn a() {
   var a = true;
   var b = false;
+  var c = true;
 }
 
 fn b() {
   let a = true;
   let b = false;
+  let c = true;
+}
+
+fn c() {
+  const a = true;
+  const b = false;
+  const c = true;
 }
 )";
 
@@ -199,11 +241,19 @@ fn b() {
 fn a() {
   var a_1 = true;
   var b_1 = false;
+  var c_1 = true;
 }
 
 fn b() {
   let a_2 = true;
   let b_2 = false;
+  let c_2 = true;
+}
+
+fn c() {
+  const a_3 = true;
+  const b_3 = false;
+  const c_3 = true;
 }
 )";
 
@@ -217,24 +267,39 @@ TEST_F(UnshadowTest, LocalShadowsFunction_OutOfOrder) {
 fn b() {
   let a = true;
   let b = false;
+  let c = true;
 }
 
 fn a() {
   var a = true;
   var b = false;
+  var c = true;
 }
 
+fn c() {
+  const a = true;
+  const b = false;
+  const c = true;
+}
 )";
 
     auto* expect = R"(
 fn b() {
   let a_1 = true;
   let b_1 = false;
+  let c_1 = true;
 }
 
 fn a() {
   var a_2 = true;
   var b_2 = false;
+  var c_2 = true;
+}
+
+fn c() {
+  const a_3 = true;
+  const b_3 = false;
+  const c_3 = true;
 }
 )";
 
@@ -254,6 +319,10 @@ fn X() {
 fn Y() {
   let a = (a == 321);
 }
+
+fn Z() {
+  const a = 321;
+}
 )";
 
     auto* expect = R"(
@@ -266,6 +335,10 @@ fn X() {
 fn Y() {
   let a_2 = (a == 321);
 }
+
+fn Z() {
+  const a_3 = 321;
+}
 )";
 
     auto got = Run<Unshadow>(src);
@@ -283,6 +356,10 @@ fn Y() {
   let a = (a == 321);
 }
 
+fn Z() {
+  const a = 321;
+}
+
 var<private> a : i32;
 )";
 
@@ -295,6 +372,10 @@ fn Y() {
   let a_2 = (a == 321);
 }
 
+fn Z() {
+  const a_3 = 321;
+}
+
 var<private> a : i32;
 )";
 
@@ -314,6 +395,10 @@ fn X() {
 fn Y() {
   let a = (a == 321);
 }
+
+fn Z() {
+  const a = 321;
+}
 )";
 
     auto* expect = R"(
@@ -326,6 +411,10 @@ fn X() {
 fn Y() {
   let a_2 = (a == 321);
 }
+
+fn Z() {
+  const a_3 = 321;
+}
 )";
 
     auto got = Run<Unshadow>(src);
@@ -343,6 +432,10 @@ fn Y() {
   let a = (a == 321);
 }
 
+fn Z() {
+  const a = 321;
+}
+
 let a : i32 = 1;
 )";
 
@@ -355,6 +448,10 @@ fn Y() {
   let a_2 = (a == 321);
 }
 
+fn Z() {
+  const a_3 = 321;
+}
+
 let a : i32 = 1;
 )";
 
@@ -363,6 +460,82 @@ let a : i32 = 1;
     EXPECT_EQ(expect, str(got));
 }
 
+TEST_F(UnshadowTest, LocalShadowsGlobalConst) {
+    auto* src = R"(
+const a : i32 = 1;
+
+fn X() {
+  var a = (a == 123);
+}
+
+fn Y() {
+  let a = (a == 321);
+}
+
+fn Z() {
+  const a = a;
+}
+)";
+
+    auto* expect = R"(
+const a : i32 = 1;
+
+fn X() {
+  var a_1 = (a == 123);
+}
+
+fn Y() {
+  let a_2 = (a == 321);
+}
+
+fn Z() {
+  const a_3 = a;
+}
+)";
+
+    auto got = Run<Unshadow>(src);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(UnshadowTest, LocalShadowsGlobalConst_OutOfOrder) {
+    auto* src = R"(
+fn X() {
+  var a = (a == 123);
+}
+
+fn Y() {
+  let a = (a == 321);
+}
+
+fn Z() {
+  const a = a;
+}
+
+const a : i32 = 1;
+)";
+
+    auto* expect = R"(
+fn X() {
+  var a_1 = (a == 123);
+}
+
+fn Y() {
+  let a_2 = (a == 321);
+}
+
+fn Z() {
+  const a_3 = a;
+}
+
+const a : i32 = 1;
+)";
+
+    auto got = Run<Unshadow>(src);
+
+    EXPECT_EQ(expect, str(got));
+}
+
 TEST_F(UnshadowTest, LocalShadowsLocalVar) {
     auto* src = R"(
 fn X() {
@@ -373,6 +546,9 @@ fn X() {
   {
     let a = (a == 321);
   }
+  {
+    const a = 321;
+  }
 }
 )";
 
@@ -385,6 +561,9 @@ fn X() {
   {
     let a_2 = (a == 321);
   }
+  {
+    const a_3 = 321;
+  }
 }
 )";
 
@@ -403,6 +582,9 @@ fn X() {
   {
     let a = (a == 321);
   }
+  {
+    const a = 321;
+  }
 }
 )";
 
@@ -415,6 +597,45 @@ fn X() {
   {
     let a_2 = (a == 321);
   }
+  {
+    const a_3 = 321;
+  }
+}
+)";
+
+    auto got = Run<Unshadow>(src);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(UnshadowTest, LocalShadowsLocalConst) {
+    auto* src = R"(
+fn X() {
+  const a = 1;
+  {
+    var a = (a == 123);
+  }
+  {
+    let a = (a == 321);
+  }
+  {
+    const a = a;
+  }
+}
+)";
+
+    auto* expect = R"(
+fn X() {
+  const a = 1;
+  {
+    var a_1 = (a == 123);
+  }
+  {
+    let a_2 = (a == 321);
+  }
+  {
+    const a_3 = a;
+  }
 }
 )";
 
@@ -432,6 +653,9 @@ fn F(a : i32) {
   {
     let a = (a == 321);
   }
+  {
+    const a = 321;
+  }
 }
 )";
 
@@ -443,6 +667,9 @@ fn F(a : i32) {
   {
     let a_2 = (a == 321);
   }
+  {
+    const a_3 = 321;
+  }
 }
 )";
 
@@ -460,6 +687,9 @@ fn a(a : i32) {
   {
     let a = (a == 321);
   }
+  {
+    const a = 321;
+  }
 }
 )";
 
@@ -471,6 +701,9 @@ fn a(a_1 : i32) {
   {
     let a_3 = (a_1 == 321);
   }
+  {
+    const a_4 = 321;
+  }
 }
 )";
 
@@ -539,6 +772,46 @@ let a : i32 = 1;
     EXPECT_EQ(expect, str(got));
 }
 
+TEST_F(UnshadowTest, ParamShadowsGlobalConst) {
+    auto* src = R"(
+const a : i32 = 1;
+
+fn F(a : bool) {
+}
+)";
+
+    auto* expect = R"(
+const a : i32 = 1;
+
+fn F(a_1 : bool) {
+}
+)";
+
+    auto got = Run<Unshadow>(src);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(UnshadowTest, ParamShadowsGlobalConst_OutOfOrder) {
+    auto* src = R"(
+fn F(a : bool) {
+}
+
+const a : i32 = 1;
+)";
+
+    auto* expect = R"(
+fn F(a_1 : bool) {
+}
+
+const a : i32 = 1;
+)";
+
+    auto got = Run<Unshadow>(src);
+
+    EXPECT_EQ(expect, str(got));
+}
+
 TEST_F(UnshadowTest, ParamShadowsAlias) {
     auto* src = R"(
 type a = i32;