From 39f487435e6aea87e33e9dd085e0b3b7bb9afdd9 Mon Sep 17 00:00:00 2001
From: Andy Balholm <andy@balholm.com>
Date: Mon, 3 Dec 2018 19:21:58 -0800
Subject: [PATCH] Support incrementing a MemberExpr that is is a pointer. Fixes
 #811 (#812)

For example, if a is a char **, now we can transpile ++*a.
---
 noarch/stdio.go     |  2 +-
 tests/operators.c   | 23 ++++++++++++++++++++++-
 transpiler/unary.go | 30 ++++++++++++++++++++----------
 3 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/noarch/stdio.go b/noarch/stdio.go
index aca3e33b6..6c0c7e9a6 100644
--- a/noarch/stdio.go
+++ b/noarch/stdio.go
@@ -112,7 +112,7 @@ func Fopen(filePath, mode *byte) *File {
 			err = file.Truncate(0)
 		}
 	default:
-		panic(fmt.Sprintf("unsupported file mode: %s", mode))
+		panic(fmt.Sprintf("unsupported file mode: %s", m))
 	}
 
 	if err != nil {
diff --git a/tests/operators.c b/tests/operators.c
index 446d9d4d6..98258e5d8 100644
--- a/tests/operators.c
+++ b/tests/operators.c
@@ -48,9 +48,13 @@ typedef unsigned char pcre_uchar;
 #define PREP_A 0x0002
 #define PREP_B 0x0010
 
+void unusedInt(int n) {
+	;
+}
+
 int main()
 {
-	plan(140);
+	plan(142);
 
     int i = 10;
     signed char j = 1;
@@ -371,6 +375,7 @@ int main()
 	}
 	{
 		int yy = 0;
+		unusedInt(yy);
 		if ((yy = simple_repeat(42)) > 3)
 		{
 			pass("ok")
@@ -505,6 +510,22 @@ int main()
         flags &= ~(PREP_A|PREP_B);
         is_eq(flags, 32);
     }
+	diag("Increment pointer in struct");
+	{
+		struct aStruct {
+			char *a;
+		} v;
+		v.a = "Hello";
+		++v.a;
+		is_streq(v.a, "ello");
+	}
+	diag("Increment pointer via poiter");
+	{
+		char *s = "World";
+		char **p = &s;
+		++*p;
+		is_streq(s, "orld");
+	}
 
 	done_testing();
 }
diff --git a/transpiler/unary.go b/transpiler/unary.go
index 13d0e10d4..8b75915a0 100644
--- a/transpiler/unary.go
+++ b/transpiler/unary.go
@@ -35,8 +35,8 @@ func transpileUnaryOperatorInc(n *ast.UnaryOperator, p *program.Program, operato
 		case token.DEC:
 			operator = token.SUB
 		}
-		var declRefExpr *ast.DeclRefExpr
-		declRefExpr, err = getSoleChildDeclRefExpr(n)
+		var e ast.Node
+		e, err = getSoleChildIncrementable(n)
 		if err != nil {
 			return
 		}
@@ -44,7 +44,7 @@ func transpileUnaryOperatorInc(n *ast.UnaryOperator, p *program.Program, operato
 		var left goast.Expr
 		var leftType string
 		var newPre, newPost []goast.Stmt
-		left, leftType, newPre, newPost, err = transpileToExpr(declRefExpr, p, false)
+		left, leftType, newPre, newPost, err = transpileToExpr(e, p, false)
 		if err != nil {
 			return
 		}
@@ -67,13 +67,8 @@ func transpileUnaryOperatorInc(n *ast.UnaryOperator, p *program.Program, operato
 
 		preStmts, postStmts = combinePreAndPostStmts(preStmts, postStmts, newPre, newPost)
 
-		var name string
-		name, err = getName(p, n.Children()[0])
-		if err != nil {
-			return
-		}
 		expr = &goast.BinaryExpr{
-			X:  goast.NewIdent(name),
+			X:  left,
 			Op: token.ASSIGN,
 			Y:  expr,
 		}
@@ -85,7 +80,7 @@ func transpileUnaryOperatorInc(n *ast.UnaryOperator, p *program.Program, operato
 			}
 			expr = util.NewAnonymousFunction([]goast.Stmt{&goast.ExprStmt{
 				X: expr,
-			}}, nil, goast.NewIdent(name), lType)
+			}}, nil, left, lType)
 		}
 		return
 	}
@@ -133,6 +128,21 @@ func transpileUnaryOperatorInc(n *ast.UnaryOperator, p *program.Program, operato
 	}, p, exprIsStmt)
 }
 
+func getSoleChildIncrementable(n ast.Node) (result ast.Node, err error) {
+	children := n.Children()
+	if len(children) != 1 {
+		return nil, fmt.Errorf("expected one child node, got %d", len(children))
+	}
+	switch c := children[0].(type) {
+	case *ast.ParenExpr:
+		return getSoleChildIncrementable(c)
+	case *ast.DeclRefExpr, *ast.MemberExpr, *ast.UnaryOperator:
+		return c, nil
+	default:
+		return nil, fmt.Errorf("unsupported type %T", c)
+	}
+}
+
 func getSoleChildDeclRefExpr(n *ast.UnaryOperator) (result *ast.DeclRefExpr, err error) {
 	var inspect ast.Node = n
 	for {