Document usage of COPT environment variable for adjusting configure flags.

Also add to the existing rather half-baked description of PROFILE,
which does exactly the same thing, but I think people use it differently.

Discussion: https://postgr.es/m/16461.1487361849@sss.pgh.pa.us

diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml
index 25a49437f1e7a02173a728ca20552b65d8c4eb28..7483731053d29ac892a89138d17b7313022cdd3f 100644 (file)
--- a/doc/src/sgml/installation.sgml
+++ b/doc/src/sgml/installation.sgml
@@ -1468,6 +1468,26 @@ su - postgres
      
     
 
+    
+     Sometimes it is useful to add compiler flags after-the-fact to the set
+     that were chosen by configure.  An important example is
+     that gcc's -Werror option cannot be included
+     in the CFLAGS passed to configure, because
+     it will break many of configure's built-in tests.  To add
+     such flags, include them in the COPT environment variable
+     while running make.  The contents of COPT
+     are added to both the CFLAGS and LDFLAGS
+     options set up by configure.  For example, you could do
+
+make COPT='-Werror'
+
+     or
+
+export COPT='-Werror'
+make
+
+    
+
     
      
       When developing code inside the server, it is recommended to
@@ -1488,6 +1508,14 @@ su - postgres
       -O0.  An easy way to do this is by passing an option
       to make: make PROFILE=-O0 file.o.
      
+
+     
+      The COPT and PROFILE environment variables are
+      actually handled identically by the PostgreSQL
+      makefiles.  Which to use is a matter of preference, but a common habit
+      among developers is to use PROFILE for one-time flag
+      adjustments, while COPT might be kept set all the time.
+     
     
    
 

diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index e1e2c0adaf200f772dc900df0021a5317a6ef67c..62fc921b8016b295008b2a01d578ec67375623b0 100644 (file)
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -582,6 +582,11 @@ ifneq ($(CUSTOM_COPT),)
   COPT= $(CUSTOM_COPT)
 endif
 
+#
+# These variables are meant to be set in the environment of "make"
+# to add flags to whatever configure picked.  Unlike the ones above,
+# they are documented.
+#
 ifdef COPT
    CFLAGS += $(COPT)
    LDFLAGS += $(COPT)