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Fix Issue 24078 - Fold constants on array concatenation only for strings

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Without this limitation, the code could incorrectly concatenate
`["c"] ~ "a" ~ "b"` as `["c"] ~ "ab"`, which was incorrect.

Signed-off-by: Teodor Dutu <teodor.dutu@gmail.com>
This commit is contained in:
Teodor Dutu 2023-08-19 08:24:13 +08:00 • committed by The Dlang Bot
parent e3eccfe9a5
commit b349b6d0de
2 changed files with 23 additions and 11 deletions
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28
compiler/src/dmd/optimize.d
View file

@ -1280,19 +1280,25 @@ Expression Expression_optimize(Expression e, int result, bool keepLvalue)
//printf("CatExp::optimize(%d) %s\n", result, e.toChars());
if (binOptimize(e, result))
return;
if (auto ce1 = e.e1.isCatExp())
{
// https://issues.dlang.org/show_bug.cgi?id=12798
// optimize ((expr ~ str1) ~ str2)
scope CatExp cex = new CatExp(e.loc, ce1.e2, e.e2);
cex.type = e.type;
Expression ex = Expression_optimize(cex, result, false);
if (ex != cex)
if (e.type == Type.tstring)
if (auto ce1 = e.e1.isCatExp())
{
e.e1 = ce1.e1;
e.e2 = ex;
// https://issues.dlang.org/show_bug.cgi?id=12798
// optimize ((expr ~ str1) ~ str2)
// https://issues.dlang.org/show_bug.cgi?id=24078
// This optimization is only valid if `expr` is a string.
// Otherwise it leads to:
// `["c"] ~ "a" ~ "b"` becoming `["c"] ~ "ab"`
scope CatExp cex = new CatExp(e.loc, ce1.e2, e.e2);
cex.type = e.type;
Expression ex = Expression_optimize(cex, result, false);
if (ex != cex)
{
e.e1 = ce1.e1;
e.e2 = ex;
}
}
}
// optimize "str"[] -> "str"
if (auto se1 = e.e1.isSliceExp())
{

6
compiler/test/runnable/test24078.d Normal file
View file

@ -0,0 +1,6 @@
//https://issues.dlang.org/show_bug.cgi?id=24078
void main()
{
assert(["c"] ~ "a" ~ "b" == ["c", "a", "b"]);
}