Add a branchdiff target for reviewing changes

Add a script and Makefile target to generate a diff PDF comparing the
current branch (and any uncommitted changes) against origin/main. It
works by building latex files for the current source, then stashing any
changes and returning to origin/main and building again, then producing
the PDF. Finally it returns to the original branch and retrieves any
stashed changes.

This is useful for reviewing spec changes before submitting patches.

The diff PDF shows additions in bold. An attempt to use change bars
resulted in corrupted output.

Usage:

   make branchdiff

Co-developed-by: Claude <[email protected]>
Signed-off-by: Simon Glass <[email protected]>

Author: sjg20

Makefile

@@ -16,8 +16,9 @@ all: latexpdf html
 help:
 	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
 	@echo "  latexdiff   to make LaTeX files including changebars against previous release"
+	@echo "  branchdiff  to make a diff PDF comparing current branch against origin/main"
 
-.PHONY: all help latexdiff Makefile
+.PHONY: all help latexdiff branchdiff Makefile
 
 latexdiff: latex
 	@echo "Generating LaTeX changebars..."
@@ -30,6 +31,12 @@ latexdiff: latex
 	@echo
 	@echo "latexdiff finished; the PDF files are in $(BUILDDIR)/latex."
 
+branchdiff:
+	@echo "Generating diff PDF against origin/main..."
+	@./scripts/make-diff-pdf
+	@echo
+	@echo "branchdiff finished; diff.pdf is in the top-level directory."
+
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: Makefile

README.md

@@ -79,10 +79,23 @@ Make commands:
 >$ make latexpdf # For generating pdf
 >$ make html # For generating a hierarchy of html pages
 >$ make singlehtml # For generating a single html page
+>$ make branchdiff # For generating a diff PDF against the main branch
 >```
 
 Output goes in ./build subdirectory.
 
+## Reviewing Changes
+
+When working on a branch, you can generate a PDF showing changes against
+origin/main:
+
+>```
+>$ make branchdiff
+>```
+
+This produces `diff.pdf` in the top-level directory with additions shown in
+bold and deletions struck through. Requires `latexdiff` to be installed.
+
 ## License ##
 This project is licensed under the Apache V2 license. More information can be found 
 in the LICENSE and NOTICE file or online at:

scripts/make-diff-pdf

@@ -0,0 +1,74 @@
+#!/bin/bash
+# SPDX-License-Identifier: Apache-2.0
+#
+# Generate a diff PDF comparing the current branch against origin/main
+# Additions shown in bold, deletions struck through
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+ROOT_DIR="$(dirname "$SCRIPT_DIR")"
+BUILD_DIR="$ROOT_DIR/build/latex"
+OLD_TEX="/tmp/fit-spec-old.tex"
+
+cd "$ROOT_DIR"
+
+# Remember current branch
+CURRENT_BRANCH=$(git branch --show-current)
+if [ -z "$CURRENT_BRANCH" ]; then
+    echo "Error: Not on a branch (detached HEAD?)"
+    exit 1
+fi
+
+echo "Generating diff: origin/main -> $CURRENT_BRANCH"
+
+# Stash any uncommitted changes
+STASH_NEEDED=false
+if ! git diff --quiet || ! git diff --cached --quiet; then
+    echo "Stashing uncommitted changes..."
+    git stash push -m "make-diff-pdf temporary stash"
+    STASH_NEEDED=true
+fi
+
+# Function to restore state on exit
+cleanup() {
+    echo "Returning to $CURRENT_BRANCH..."
+    git checkout "$CURRENT_BRANCH" 2>/dev/null || true
+    if [ "$STASH_NEEDED" = true ]; then
+        echo "Restoring stashed changes..."
+        git stash pop || true
+    fi
+}
+trap cleanup EXIT
+
+# Build origin/main
+echo "Building origin/main..."
+git checkout origin/main
+make latex > /dev/null 2>&1
+cp "$BUILD_DIR/fit-specification.tex" "$OLD_TEX"
+
+# Build current branch (cleanup trap will checkout)
+echo "Building $CURRENT_BRANCH branch..."
+git checkout "$CURRENT_BRANCH"
+if [ "$STASH_NEEDED" = true ]; then
+    git stash pop
+    STASH_NEEDED=false
+fi
+make latex > /dev/null 2>&1
+
+# Generate diff in build/latex directory (where Sphinx class files are)
+echo "Running latexdiff..."
+latexdiff --type=BOLD "$OLD_TEX" "$BUILD_DIR/fit-specification.tex" \
+    > "$BUILD_DIR/diff.tex" 2>/dev/null
+
+# Compile PDF (twice for cross-references)
+echo "Compiling PDF..."
+cd "$BUILD_DIR"
+pdflatex -interaction=nonstopmode diff.tex > /dev/null 2>&1
+pdflatex -interaction=nonstopmode diff.tex > /dev/null 2>&1
+
+# Move PDF to root and clean up
+mv diff.pdf "$ROOT_DIR/"
+rm -f diff.aux diff.log diff.out diff.toc diff.idx diff.ind diff.ilg diff.tex 2>/dev/null
+
+echo "Done: $ROOT_DIR/diff.pdf"