options specific to @code{gcj}.
@menu
-* Input Options:: How to find input files
+* Input Options:: How gcj finds files
* Encodings:: Options controlling source file encoding
* Warnings:: Options controlling warnings specific to gcj
* Code Generation:: Options controlling the output of gcj
@cindex class path
-@code{gcj} has options to control where it looks to find input files.
-Like other compilers for the Java language, @code{gcj} has a notion of a
-@dfn{class path}. There are several options and environment variables
-which can be used to manipulate the class path. When @code{gcj} looks
-for a given class, it searches the class path looking for the
-corresponding @file{.class} file. @code{gcj} comes with a built-in
-class path which points at the installed @file{libgcj.jar}, a file which
-contains all the standard classes.
+@code{gcj} has options to control where it looks to find files it needs.
+For instance, @code{gcj} might need to load a class that is referenced
+by the file it has been asked to compile. Like other compilers for the
+Java language, @code{gcj} has a notion of a @dfn{class path}. There are
+several options and environment variables which can be used to
+manipulate the class path. When @code{gcj} looks for a given class, it
+searches the class path looking for the corresponding @file{.class}
+file. @code{gcj} comes with a built-in class path which points at the
+installed @file{libgcj.jar}, a file which contains all the standard
+classes.
In the below, a directory or path component can refer either to an
actual directory on the filesystem, or to a @file{.zip} or @file{.jar}
default being the opposite of what is listed.
@table @code
-@item -Wunsupported-jdk11
-This will cause @code{gcj} to warn that @code{final} local variables are
-being treated as non-final.
-@c FIXME: why do we want this? Is it just not implemented yet?
-
@item -Wredundant-modifiers
With this flag, @code{gcj} will warn about redundant modifiers. For
instance, it will warn if an interface method is declared @code{public}.
@table @code
@item --main=@var{CLASSNAME}
-This option is used when linking. Since the linker expects to find a
-method simply named @code{main}, and since Java programs won't have such
-a method (due to name mangling), at link time @code{gcj} will generate a
-stub @code{main} function which will initialize the runtime and then
-invoke the @code{main} method of the appropriate class. This option is
-used to specify the name of the class whose @code{main} method should be
-invoked when the resulting executable is run.
+This option is used when linking to specify the name of the class whose
+@code{main} method should be invoked when the resulting executable is
+run. @footnote{The linker by default looks for a global function named
+@code{main}. Since Java does not have global functions, and a
+collection of Java classes may have more than one class with a
+@code{main} method, you need to let the linker know which of those
+@code{main} methods it should invoke when starting the application.}
@item -D@var{name}[=@var{value}]
This option can only be used with @code{--main}. It defines a system
default they will be put in subdirectories of the current working
directory.
-@c @item -fassume-compiled
-@c Nobody is sure what this does and anyway it doesn't work.
-
@item -fno-bounds-check
By default, @code{gcj} generates code which checks the bounds of all
array indexing operations. With this option, these checks are omitted.
@node Compatibility
-@chapter Compatibility
+@chapter Compatibility with the Java Platform
As we believe it is important that the Java platform not be fragmented,
@code{gcj} and @code{libgcj} try to conform to the relevant Java
it).
@item
-@code{libgcj} is missing many packages, most notably @code{java.awt}.
+@code{libgcj} is largely compatible with the JDK 1.2 libraries.
+However, @code{libgcj} is missing many packages, most notably
+@code{java.awt}. There are also individual missing classes and methods.
+We currently do not have a list showing differences between
+@code{libgcj} and the Java 2 platform.
@item
Sometimes the @code{libgcj} implementation of a method or class differs
Disassemble method bodies. By default method bodies are not printed.
@item --javap
-Generate output in @code{javap} format.
+Generate output in @code{javap} format. The implementation of this
+feature is very incomplete.
@item --classpath=@var{path}
@itemx --CLASSPATH=@var{path}
@node Resources
@chapter Resources
+While writing @code{gcj} and @code{libgcj} we have, of course, relied
+heavily on documentation from Sun Microsystems. In particular we have
+used The Java Language Specification (both first and second editions),
+the Java Class Libraries (volumes one and two), and the Java Virtual
+Machine Specification. In addition we've used the online documentation
+at @uref{http://java.sun.com/}.
+
The current @code{gcj} home page is
@uref{http://sources.redhat.com/java/}. This is likely to change in the
near future.
projects / gcc.git / commitdiff