[GNATS 23530] Spurious diagnostic for previously declared gnu_inline attribute

[jhsedg]

Customer bug ID

geometry tests

Description

​extern inline int f();
​__attribute((gnu_inline)) extern inline int f() { return 0; }
​
​[ellen@lin1 boost_1_74_0]$ $CPFEB --gnu_version 80100 -tused --c++17 /tmp/p.C
​"/tmp/p.C", line 2: error: function was previously declared without the
​ "gnu_inline" attribute
​ __attribute((gnu_inline)) extern inline int f() { return 0; }
​ ^
​
​1 error detected in the compilation of "/tmp/p.C".

Notes

​mjh, 2020-11-10:
​
​Here's a better reproducer:
​
​//options_all:--gn 80100
​extern int f();
​extern inline attribute ((gnu_inline)) int f() { return 0; }
​
​The issue here is that the cp_gen_be config that was being used had CP_GEN_BE_TARGET_MATCHES_SOURCE_DIALECT set to FALSE, so "inline" was being emitted rather than the gnu_inline attribute in the declaration case leading to this generated C++:
​
​extern inline int f();
​__attribute((gnu_inline)) extern inline int f() { return 0; }
​
​That causes the error that was reported when compiling the output (a valid diagnostic).
​
​Reducing the severity of this.