不带 -Wdeclaration-after-statement 的 PostgreSQL C 扩展

Question

目前，当我编译我的扩展时，我得到，

warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
   57 |  uint32 n = fctx->n;

PostgreSQL 当前在编译期间使用 -Wdeclaration-after-statement。他们在我机器上的 pgxs 全局 make 文件中专门设置了这个选项，该文件位于

/usr/lib/postgresql/13/lib/pgxs/src/Makefile.global

是用他们CFLAGS,

设置的

CFLAGS = -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -Wno-format-truncation -Wno-stringop-truncation -g -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -fno-omit-frame-pointer

是否可以禁用 -Wdeclaration-after-statement 或者每个 PostgreSQL 扩展作者都必须采用相同的约定？我可以在我的扩展中覆盖 CFLAGS 吗？

Answer 1

您可能可以按照 link

中描述的说明覆盖它

变量PG_CFLAGS会附加到CFLAGS，所以只需要加上-Wno-declaration-after-statement

Answer 2

我能够通过结束我的扩展程序的 Makefile 来消除这些警告，例如，

PG_CFLAGS += $(PERMIT_DECLARATION_AFTER_STATEMENT)
include $(PGXS)

RhodiumToad 在 include $(PGXS)

之后提供了另一种方法

include $(PGXS)
$(OBJS): CFLAGS += $(PERMIT_DECLARATION_AFTER_STATEMENT)

感谢 ircs://irc.libera.chat:6697/#postgresql 上的 RhodiumToad，他接着说

configure tests whether -Wno-declaration-after-statement works and sets up that variable accordingly well actually I think it checks for -Wdeclaration-after-statement and if that works, assumes -Wno-... works too you can put that rule after including $(PGXS), so you can make it conditional on $(MAJORVERSION) if need be or conditional on PERMIT_DECLARATION_AFTER_STATEMENT being defined

不带 -Wdeclaration-after-statement 的 PostgreSQL C 扩展

PostgreSQL C Extensions without -Wdeclaration-after-statement

c

postgresql

makefile

postgresql-extensions