From 9cd7f827f418cf955add8d183c751c4e84498bbe Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Wed, 15 Nov 2023 00:36:35 +0900
Subject: [PATCH] internal/shaderir: bug fix: constants must be truncated
 correctly in an array

Closes #2840
---
 internal/shader/expr.go                       | 28 ++++++++++++++++++-
 .../shader/testdata/issue2840.expected.vs     | 16 +++++++++++
 internal/shader/testdata/issue2840.go         |  9 ++++++
 3 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 internal/shader/testdata/issue2840.expected.vs
 create mode 100644 internal/shader/testdata/issue2840.go

diff --git a/internal/shader/expr.go b/internal/shader/expr.go
index 859718170..abfebae85 100644
--- a/internal/shader/expr.go
+++ b/internal/shader/expr.go
@@ -854,6 +854,32 @@ func (cs *compileState) parseExpr(block *block, fname string, expr ast.Expr, mar
 				cs.addError(e.Pos(), "multiple-value context is not available at a composite literal")
 				return nil, nil, nil, false
 			}
+
+			expr := exprs[0]
+			if expr.Const != nil {
+				switch t.Sub[0].Main {
+				case shaderir.Bool:
+					if expr.Const.Kind() != gconstant.Bool {
+						cs.addError(e.Pos(), fmt.Sprintf("cannot %s to type bool", expr.Const.String()))
+					}
+				case shaderir.Int:
+					if !canTruncateToInteger(expr.Const) {
+						cs.addError(e.Pos(), fmt.Sprintf("constant %s truncated to integer", expr.Const.String()))
+						return nil, nil, nil, false
+					}
+					expr.Const = gconstant.ToInt(expr.Const)
+				case shaderir.Float:
+					if !canTruncateToFloat(expr.Const) {
+						cs.addError(e.Pos(), fmt.Sprintf("constant %s truncated to float", expr.Const.String()))
+						return nil, nil, nil, false
+					}
+					expr.Const = gconstant.ToFloat(expr.Const)
+				default:
+					cs.addError(e.Pos(), fmt.Sprintf("constant %s cannot be used for the array type %s", expr.Const.String(), t.String()))
+					return nil, nil, nil, false
+				}
+			}
+
 			stmts = append(stmts, ss...)
 			stmts = append(stmts, shaderir.Stmt{
 				Type: shaderir.Assign,
@@ -871,7 +897,7 @@ func (cs *compileState) parseExpr(block *block, fname string, expr ast.Expr, mar
 							},
 						},
 					},
-					exprs[0],
+					expr,
 				},
 			})
 		}
diff --git a/internal/shader/testdata/issue2840.expected.vs b/internal/shader/testdata/issue2840.expected.vs
new file mode 100644
index 000000000..1b4e506ae
--- /dev/null
+++ b/internal/shader/testdata/issue2840.expected.vs
@@ -0,0 +1,16 @@
+float[1] F0(void);
+int[1] F1(void);
+
+float[1] F0(void) {
+	float l0[1];
+	l0[0] = float(0);
+	(l0)[0] = 1.0;
+	return l0;
+}
+
+int[1] F1(void) {
+	int l0[1];
+	l0[0] = 0;
+	(l0)[0] = 1;
+	return l0;
+}
diff --git a/internal/shader/testdata/issue2840.go b/internal/shader/testdata/issue2840.go
new file mode 100644
index 000000000..1dfe6e827
--- /dev/null
+++ b/internal/shader/testdata/issue2840.go
@@ -0,0 +1,9 @@
+package main
+
+func Floats() [1]float {
+	return [1]float{1}
+}
+
+func Ints() [1]int {
+	return [1]int{1.0}
+}