When processing this program, the compiler will produce this warning:
@example
-file: /tmp/foo.lisp
-
-in: DEFUN FOO
-(ZOQ Y)
---> ROQ PLOQ +
-==>
-Y
-caught WARNING:
-Result is a SYMBOL, not a NUMBER.
+; file: /tmp/foo.lisp
+; in: DEFUN FOO
+; (ZOQ Y)
+; --> ROQ PLOQ
+; ==>
+; (+ Y 3)
+;
+; caught WARNING:
+; Asserted type NUMBER conflicts with derived type (VALUES SYMBOL &OPTIONAL).
@end example
In this example we see each of the six possible parts of a compiler
@enumerate
@item
-@samp{File: /tmp/foo.lisp} This is the name of the file that the
+@findex with-compilation-unit
+@samp{file: /tmp/foo.lisp} This is the name of the file that the
compiler read the relevant code from. The file name is displayed
because it may not be immediately obvious when there is an error
during compilation of a large system, especially when
@code{foo}.
@item
+@cindex Original Source
@samp{(ZOQ Y)} This is the @dfn{original source} form responsible for
the error. Original source means that the form directly appeared in
the original input to the compiler, i.e. in the lambda passed to
for the error.
@item
-@samp{--> ROQ PLOQ +} This is the @dfn{processing path} that the
+@cindex Processing Path
+@samp{--> ROQ PLOQ} This is the @dfn{processing path} that the
compiler used to produce the errorful code. The processing path is a
representation of the evaluated forms enclosing the actual source that
the compiler encountered when processing the original source. The
path is the first element of each form, or the form itself if the form
is not a list. These forms result from the expansion of macros or
source-to-source transformation done by the compiler. In this
-example, the enclosing evaluated forms are the calls to @code{roq},
-@code{ploq} and @code{+}. These calls resulted from the expansion of
-the @code{zoq} macro.
+example, the enclosing evaluated forms are the calls to @code{roq} and
+@code{ploq}. These calls resulted from the expansion of the
+@code{zoq} macro.
@item
-@samp{==> Y} This is the @dfn{actual source} responsible for the
+@cindex Actual Source
+@samp{==> (+ Y 3)} This is the @dfn{actual source} responsible for the
error. If the actual source appears in the explanation, then we print
the next enclosing evaluated form, instead of printing the actual
source twice. (This is the form that would otherwise have been the
with the evaluation of the reference to the variable @code{y}.
@item
-@samp{caught WARNING: Result is a SYMBOL, not a NUMBER.} This is the
-@dfn{explanation} of the problem. In this example, the problem is that
-@code{y} evaluates to a symbol, but is in a context where a number is
-required (the argument to @code{+}).
+@samp{caught WARNING: Asserted type NUMBER conflicts with derived type
+(VALUES SYMBOL &OPTIONAL).} This is the @dfn{explanation} of the
+problem. In this example, the problem is that, while the call to
+@code{+} requires that its arguments are all of type @code{number},
+the compiler has derived that @code{y} will evaluate to a
+@code{symbol}. Note that @samp{(VALUES SYMBOL &OPTIONAL)} expresses
+that @code{y} evaluates to precisely one value.
@end enumerate
@item
The actual source form is indented like the original source, but is
marked by a preceding @samp{==>} line.
-
+@comment no it isn't.
@item
The explanation is prefixed with the error severity, which can be
first. For example:
@example
-file: /tmp/foo.lisp
-
-in: DEFUN FOO
-(ZOQ Y)
---> ROQ
-==>
-(PLOQ (+ Y 3))
-caught STYLE-WARNING:
-undefined function: PLOQ
-
-==>
-(ROQ (PLOQ (+ Y 3)))
-caught STYLE-WARNING:
-undefined function: ROQ
+; file: /tmp/foo.lisp
+; in: DEFUN FOO
+; (ZOQ Y)
+; --> ROQ
+; ==>
+; (PLOQ (+ Y 3))
+;
+; caught STYLE-WARNING:
+; undefined function: PLOQ
+
+; ==>
+; (ROQ (PLOQ (+ Y 3)))
+;
+; caught STYLE-WARNING:
+; undefined function: ROQ
@end example
+@comment fixing that weird blank line might be good
In this example, the file, definition and original source are
identical for the two messages, so the compiler omits them in the
@node The Original and Actual Source
@comment node-name, next, previous, up
@subsection The Original and Actual Source
+@cindex Original Source
+@cindex Actual Source
The @emph{original source} displayed will almost always be a list. If
the actual source for an error message is a symbol, the original
gives this error message
@example
-in: DEFUN BAR
-(LET (A) (DECLARE (FIXNUM A)) (SETQ A (FOO X)) A)
-caught WARNING: The binding of A is not a FIXNUM:
-NIL
+; file: /tmp/foo.lisp
+; in: DEFUN BAR
+; (LET (A)
+; (DECLARE (FIXNUM A))
+; (SETQ A (FOO X))
+; A)
+;
+; caught WARNING:
+; Asserted type FIXNUM conflicts with derived type (VALUES NULL &OPTIONAL).
@end example
This error message is not saying ``there is a problem somewhere in
Compiling results in this error message:
@example
-in: DEFUN FOO
-(DOTIMES (I N *UNDEFINED*))
---> DO BLOCK LET TAGBODY RETURN-FROM
-==>
-(PROGN *UNDEFINED*)
-caught STYLE-WARNING:
-undefined variable: *UNDEFINED*
+; in: DEFUN FOO
+; (DOTIMES (I N *UNDEFINED*))
+; --> DO BLOCK LET TAGBODY RETURN-FROM
+; ==>
+; (PROGN *UNDEFINED*)
+;
+; caught WARNING:
+; undefined variable: *UNDEFINED*
@end example
Note that @code{do} appears in the processing path. This is because
@emph{note}, is used for problems which are too mild for the standard
condition classes, typically hints about how efficiency might be
improved.
-
+@comment mention sb-ext:compiler-note
@node Errors During Macroexpansion
@comment node-name, next, previous, up
gives this error:
@example
-in: DEFUN FOO
-(DO ((CURRENT L #) (# NIL)) (WHEN (EQ # E) (RETURN CURRENT)) )
-caught ERROR:
-(in macroexpansion of (DO # #))
-(hint: For more precise location, try *BREAK-ON-SIGNALS*.)
-DO step variable is not a symbol: (ATOM CURRENT)
+; in: DEFUN FOO
+; (DO ((CURRENT L (CDR CURRENT))
+; ((ATOM CURRENT) NIL))
+; (WHEN (EQ (CAR CURRENT) E) (RETURN CURRENT)))
+;
+; caught ERROR:
+; (in macroexpansion of (DO # #))
+; (hint: For more precise location, try *BREAK-ON-SIGNALS*.)
+; DO step variable is not a symbol: (ATOM CURRENT)
@end example
@subsection Read Errors
@cindex Read errors, compiler
-SBCL's compiler (unlike CMUCL's) does not attempt to recover from read
-errors when reading a source file, but instead just reports the
-offending character position and gives up on the entire source file.
+SBCL's compiler does not attempt to recover from read errors when
+reading a source file, but instead just reports the offending
+character position and gives up on the entire source file.
@c <!-- FIXME: How much control over error messages is in SBCL?
(@pxref{Efficiency}), the use of appropriate type declarations can be
very important for performance as well.
-The SBCL compiler, like the related compiler in CMUCL, treats type
-declarations much differently than other Lisp compilers. By default
-(@emph{i.e.}, at ordinary levels of the @code{safety} compiler
-optimization parameter), the compiler doesn't blindly believe most
-type declarations; it considers them assertions about the program that
-should be checked.
+@findex safety
+The SBCL compiler treats type declarations differently from most other
+Lisp compilers. By default (@emph{i.e.}, at ordinary levels of the
+@code{safety} compiler optimization parameter), the compiler doesn't
+blindly believe most type declarations; it considers them assertions
+about the program that should be checked.
+@findex satisfies
The SBCL compiler also has a greater knowledge of the
Common Lisp type system than other compilers. Support is incomplete
-only for the @code{not}, @code{and} and @code{satisfies}
-types.
+only for types involving the @code{satisfies} type specifier.
@c <!-- FIXME: See also sections \ref{advanced-type-stuff}
@c and \ref{type-inference}, once we snarf them from the
@c CMU CL manual. -->
+@c Also see my paper on improving Baker, when I get round to it.
@menu
* Type Errors at Compile Time::
Compilation produces this warning:
@example
-in: DEFUN RAZ
-(CASE FOO (:THIS 13) (:THAT 9) (:THE-OTHER 42))
---> LET COND IF COND IF COND IF
-==>
-(COND)
-caught WARNING: This is not a FIXNUM:
-NIL
+; in: DEFUN RAZ
+; (CASE FOO (:THIS 13) (:THAT 9) (:THE-OTHER 42))
+; --> LET COND IF COND IF COND IF
+; ==>
+; (COND)
+;
+; caught WARNING:
+; This is not a FIXNUM:
+; NIL
@end example
In this case, the warning means that if @code{foo} isn't any of
executed), so it compiles the erroneous code (which will always signal
an error if it is executed) and gives a warning.
-
Type warnings are inhibited when the @code{sb-ext:inhibit-warnings}
optimization quality is @code{3}. @xref{Compiler Policy}. This
can be used in a local declaration to inhibit type warnings in a code
@cindex Compatibility with other Lisps
@c (should also have an entry in the non-ANSI-isms section)-->
-Since SBCL's compiler, like CMUCL's compiler, does much more
-comprehensive type checking than most Lisp compilers, SBCL may detect
-type errors in programs that have been debugged using other
-compilers. These errors are mostly incorrect declarations, although
-compile-time type errors can find actual bugs if parts of the program
-have never been tested.
+Since SBCL's compiler does much more comprehensive type checking than
+most Lisp compilers, SBCL may detect type errors in programs that have
+been debugged using other compilers. These errors are mostly incorrect
+declarations, although compile-time type errors can find actual bugs
+if parts of the program have never been tested.
Some incorrect declarations can only be detected by run-time type
checking. It is very important to initially compile a program with
whether to inline operations, which tend to increase the size of
programs. Use the value @code{0} with caution, since it can cause the
compiler to inline operations so indiscriminately that the net effect
-is to slow the program by causing cache misses or swapping.
+is to slow the program by causing cache misses or even swapping.
@c <!-- FIXME: old CMU CL compiler policy, should perhaps be adapted
@c _ for SBCL. (Unfortunately, the CMU CL docs are out of sync with the
redefine standard functions, users sometimes want to implicitly
redefine these functions when they are debugging using the
@code{trace} macro. Special-casing of standard functions can be
-inhibited using the @code{notinline} declaration.
+inhibited using the @code{notinline} declaration, but even then some
+phases of analysis such as type inferencing are applied by the
+compiler.
@item
The compiler can have multiple alternate implementations of standard
projects / sbcl.git / blobdiff