• d-bugmail puremagic.com (46/46) Mar 28 2019 https://issues.dlang.org/show_bug.cgi?id=19769

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=19769

          Issue ID: 19769
           Summary: CTFE format(): str[index] is used before initialized
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody puremagic.com
          Reporter: elpenguino+D gmail.com

trying to format the result of a const asCapitalized(string) at compile-time
causes a used-before-initialized error in std.utf.decode(), as demonstrated
below:

```
import std.uni;
import std.format;
static immutable x = format("%s", cast(const)"test".asCapitalized);
```

results in this error:

```
/dlang/dmd/linux/bin64/../../src/phobos/std/utf.d(1132): Error: str[index] is
used before initialized
/dlang/dmd/linux/bin64/../../src/phobos/std/uni.d(9143):        originally
uninitialized here
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(3457):        called from
here: decode(str, i)
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(4233):        called from
here: formatElement(w, e, f)
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(1854):        called from
here: formatValueImpl(w, val, f)
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(3552):        called from
here: formatValue(w, val, f)
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(4233):        called from
here: formatElement(w, e, f)
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(1854):        called from
here: formatValueImpl(w, val, f)
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(575):        called from
here: formatValue(w, _param_2, spec)
/dlang/dmd/linux/bin64/../../src/phobos/std/format.d(6403):        called from
here: formattedWrite(w, fmt, _param_1)
onlineapp.d(3):        called from here: format("%s", asCapitalized("test"))
```

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