Changes between Version 7 and Version 8 of Building/Modifying

Timestamp:

09/21/10 07:49:36 (3 years ago)

Author:

simonmar

Comment:

document make TRACE=1

Building/Modifying

@@ -19 +19 @@
 you thought it was.  How do you go about debugging the build system?
 
-Debugging techniques can also be a handy way to understand how the build system works.  Want to test your hypothesis about what the variable `rts_C_SRCS` contains?  Just add a `$(warning $(rts_C_SRCS))` somewhere.
-
 Here are the techniques that we use.  Note, for many of these diagnosis techniques you may want to invoke
 '''make''' on `ghc.mk` directly using `make -f ghc.mk`, to bypass the
 [wiki:Building/Architecture/Idiom/PhaseOrdering phase ordering] machinery of the top-level
 `Makefile`.
+
+ `$(warning ... message ...)`::
+  equivalent to "printf-debugging` in a C program: this causes
+  '''make''' to print a message when it reads the `$(warning ..)`
+  expression, and the message can include variable references.  Very
+  useful for finding out what '''make''' thinks the value of a
+  variable is at a particular point in the `Makefile`, or for finding
+  out the parameters for a particular macro call.    Want to test your hypothesis about what the variable `rts_C_SRCS` contains?  Just add a `$(warning $(rts_C_SRCS))` somewhere.
+
+ `make show VALUE=VAR`::
+  prints the value of variable `VAR`.  Useful for quick diagnosis.
+
+ `make TRACE=1`::
+  prints messages about certain macros that are called and their arguments.  This is basically a system of `$(warning)` calls enabled when the value of `$(TRACE)` is non-empty.  To see how it works, look at the file [[GhcFile(rules/trace.mk)]], and feel free to add trace calls to more places in the build system.
 
  `make --debug=b --debug=m`::
@@ -36 +48 @@
   huge; so pipe it to a file, and search through it for the bits of
   interest.
-
- `$(warning ... message ...)`::
-  equivalent to "printf-debugging` in a C program: this causes
-  '''make''' to print a message when it reads the `$(warning ..)`
-  expression, and the message can include variable references.  Very
-  useful for finding out what '''make''' thinks the value of a
-  variable is at a particular point in the `Makefile`, or for finding
-  out the parameters for a particular macro call.
-
- `make show VALUE=VAR`::
-  prints the value of variable `VAR`.  Useful for quick diagnosis.
 
 == Scenarios ==