[flang][runtime] Fix use of empty optional in BOZ input (llvm#120789)

klausler · web-flow · commit 7463b46a34ef · 2025-01-08T13:12:25.000-08:00
Slava reported a valgrind result showing the use of uninitialized data
due to an unconditional dereference of an optional in BOZ formatted
input editing; fix.
diff --git a/flang/runtime/edit-input.cpp b/flang/runtime/edit-input.cpp
@@ -130,7 +130,7 @@ static RT_API_ATTRS bool EditBOZInput(
     shift = shift - 8; // misaligned octal
   }
   while (digits > 0) {
-    char32_t ch{*io.NextInField(remaining, edit)};
+    char32_t ch{io.NextInField(remaining, edit).value_or(' ')};
     int digit{0};
     if (ch == ' ' || ch == '\t') {
       if (edit.modes.editingFlags & blankZero) {

Original file line number	Diff line number	Diff line change
`@@ -130,7 +130,7 @@ static RT_API_ATTRS bool EditBOZInput(`
`130`	`130`	`shift = shift - 8; // misaligned octal`
`131`	`131`	`}`
`132`	`132`	`while (digits > 0) {`
`133`		`- char32_t ch{*io.NextInField(remaining, edit)};`
	`133`	`+ char32_t ch{io.NextInField(remaining, edit).value_or(' ')};`
`134`	`134`	`int digit{0};`
`135`	`135`	`if (ch == ' ' \|\| ch == '\t') {`
`136`	`136`	`if (edit.modes.editingFlags & blankZero) {`