[DAFFODIL-2578] Raise minimum C level to ISO C11 with GNU extensions

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.2.0
• Component/s: Back End C-Generator
• Assignee: Unassigned
• Reporter: John Interrante
• Created: 03/Nov/21 18:38
• Updated: 08/Nov/21 13:01
• Resolved: 04/Nov/21 13:05

Description

Fix pedantic warning "ISO C99 doesn't support unnamed structs/unions" found when compiling nested.dfdl.xsd's NestedUnion example with current Makefile's CFLAGS. Verify that both gcc and clang support "-std=gnu11" all the way back to gcc-4 and clang-3 on CentOS 7. Raise runtime2's minimum C language support level to ISO C11 with GNU extensions and make all the places where Daffodil calls the C compiler pass "-std=gnu11" to the C compiler to compile code with the same minimum C level. ISO C11 also allows "for (" loops to define loop variables in place so we can make that change too.