[flang][runtime] Fix namelist substring checking (#78649)

klausler · web-flow · commit 15e4a3c1fb12 · 2024-01-25T15:15:20.000-08:00
An || operator in namelist substring bounds checking really needs to be
an &amp;&amp; operator so that the substring is viewed as correct only when both
its bounds are valid.

Fixes llvm-test-suite/Fortran/gfortran/regression/namelist_40.f90.
diff --git a/flang/runtime/namelist.cpp b/flang/runtime/namelist.cpp
@@ -313,7 +313,7 @@ static bool HandleSubstring(
         desc.raw().elem_len = 0;
         return true;
       }
-      if (*lower >= 1 || *upper <= chars) {
+      if (*lower >= 1 && *upper <= chars) {
         // Offset the base address & adjust the element byte length
         desc.raw().elem_len = (*upper - *lower + 1) * kind;
         desc.set_base_addr(reinterpret_cast<void *>(

Original file line number	Diff line number	Diff line change
`@@ -313,7 +313,7 @@ static bool HandleSubstring(`
`313`	`313`	`desc.raw().elem_len = 0;`
`314`	`314`	`return true;`
`315`	`315`	`}`
`316`		`- if (lower >= 1 \|\| upper <= chars) {`
	`316`	`+ if (lower >= 1 && upper <= chars) {`
`317`	`317`	`// Offset the base address & adjust the element byte length`
`318`	`318`	`desc.raw().elem_len = (upper - lower + 1) * kind;`
`319`	`319`	`desc.set_base_addr(reinterpret_cast<void *>(`