Convert public char* to const char* for C++ compatibility.

.github/workflows/cmake_actions.yml

@@ -1,4 +1,4 @@
-name: Build with CMake
+name: Test CMake build
 
 on: [push, pull_request]
 
@@ -7,6 +7,7 @@ jobs:
     name:
       Cmake
     strategy:
+      fail-fast: false
       matrix:
         cc:          [gcc, clang]
         cmake_flags: ["",

.github/workflows/make_actions.yml

@@ -1,4 +1,4 @@
-name: Build with Make
+name: Test Make build
 
 on: [push, pull_request]
 
@@ -7,6 +7,7 @@ jobs:
     name:
       Make
     strategy:
+      fail-fast: false
       matrix:
         cc:         [gcc, clang]
         make_flags: ["",

.github/workflows/make_cpp.yml

@@ -0,0 +1,32 @@
+name: Test CPP build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name:
+      Make
+    strategy:
+      fail-fast: false
+      matrix:
+        cc:         [gcc, clang]
+
+    runs-on: ubuntu-latest
+    env:
+      CC:     ${{ matrix.cc }}
+      CXX:    ${{ matrix.cxx }}
+      CFLAGS: '-Werror -Wno-deprecated'
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Install dependencies
+      run: |
+        sudo apt update
+        sudo apt-get -y install zlib1g-dev
+
+    - name: make
+      run: |
+        make V=1
+        make examples_cpp V=1 CC=${{ matrix.cxx }}
+

.github/workflows/windows_build.yml

@@ -1,4 +1,4 @@
-name: Cmake on Windows
+name: Test Cmake build on Windows
 
 on: [push, pull_request]
 

.github/workflows/zig_build.yml

@@ -17,6 +17,6 @@ jobs:
       - uses: goto-bus-stop/setup-zig@v2
         with:
           version: master
-      
+
       - name: Build Summary
         run: zig build -DBUILD_TESTS -DBUILD_EXAMPLES -DUSE_SYSTEM_MINIZIP --summary all -freference-trace

Makefile

@@ -64,6 +64,10 @@ universal_binary :
 examples : all
 	$(Q)$(MAKE) -C examples
 
+# Build the example programs with CPP for compatibility checking.
+examples_cpp : all
+	$(Q)$(MAKE) -C examples CC=$(CXX)
+
 # Clean src and test directories.
 clean :
 	$(Q)$(MAKE) clean -C src

examples/autofilter.c

@@ -268,7 +268,7 @@ int main() {
     worksheet_autofilter(worksheet5, 0, 0, 50, 3);
 
     /* Add the filter criteria. */
-    char* list[] = {"East", "North", "South", NULL};
+    const char* list[] = {"East", "North", "South", NULL};
 
     worksheet_filter_list(worksheet5, 0, list);
 

examples/chart_data_labels.c

@@ -263,7 +263,7 @@ int main() {
      * font for the custom items as an extra example.
      */
     lxw_chart_data_label data_label7_1 = {.value = "=Sheet1!$C$2", .font = &font2};
-    lxw_chart_data_label data_label7_2 = {0};
+    lxw_chart_data_label data_label7_2 = {};
     lxw_chart_data_label data_label7_3 = {.value = "=Sheet1!$C$4", .font = &font2};
     lxw_chart_data_label data_label7_4 = {.value = "=Sheet1!$C$5", .font = &font2};
 

examples/chart_styles.c

@@ -13,7 +13,7 @@
 int main() {
 
     int chart_types[]    = {LXW_CHART_COLUMN, LXW_CHART_AREA, LXW_CHART_LINE, LXW_CHART_PIE};
-    char *chart_names[]  = {"Column", "Area", "Line", "Pie"};
+    const char *chart_names[]  = {"Column", "Area", "Line", "Pie"};
     char chart_title[32] = {0};
     int row_num, col_num, chart_num, style_num;
     lxw_worksheet *worksheet;

examples/conditional_format1.c

@@ -32,7 +32,8 @@ int main() {
     format_set_font_color(custom_format, LXW_COLOR_RED);
 
     /* Create a conditional format object. A static object would also work. */
-    lxw_conditional_format *conditional_format = calloc(1, sizeof(lxw_conditional_format));
+    lxw_conditional_format *conditional_format =
+        (lxw_conditional_format *)calloc(1, sizeof(lxw_conditional_format));
 
     /* Set the format type: a cell conditional: */
     conditional_format->type     = LXW_CONDITIONAL_TYPE_CELL;

examples/conditional_format2.c

@@ -61,7 +61,8 @@ int main() {
     format_set_font_color(format2, 0x006100);
 
     /* Create a single conditional format object to reuse in the examples. */
-    lxw_conditional_format *conditional_format = calloc(1, sizeof(lxw_conditional_format));
+    lxw_conditional_format *conditional_format =
+        (lxw_conditional_format *)calloc(1, sizeof(lxw_conditional_format));
 
     /*
      * Example 1. Conditional formatting based on simple cell based criteria.

examples/data_validate.c

@@ -47,7 +47,8 @@ int main() {
 
     lxw_workbook        *workbook  = workbook_new("data_validate1.xlsx");
     lxw_worksheet       *worksheet = workbook_add_worksheet(workbook, NULL);
-    lxw_data_validation *data_validation = calloc(1, sizeof(lxw_data_validation));
+    lxw_data_validation *data_validation =
+        (lxw_data_validation *)calloc(1, sizeof(lxw_data_validation));
 
     /* Add a format to use to highlight the header cells. */
     lxw_format *format = workbook_add_format(workbook);
@@ -154,7 +155,7 @@ int main() {
                            "Select a value from a drop down list",
                            NULL);
 
-    char *list[] = {"open", "high", "close", NULL};
+    const char *list[] = {"open", "high", "close", NULL};
 
     data_validation->validate   = LXW_VALIDATION_TYPE_LIST;
     data_validation->value_list = list;

examples/dates_and_times04.c

@@ -18,7 +18,7 @@ int main() {
     /* Examples date and time formats. In the output file compare how changing
      * the format strings changes the appearance of the date.
      */
-    char *date_formats[] = {
+    const char *date_formats[] = {
         "dd/mm/yy",
         "mm/dd/yy",
         "dd m yy",

examples/format_num_format.c

@@ -62,7 +62,7 @@ int main() {
     /* Format a Zip code. */
     format_set_num_format(format11, "00000");
     worksheet_write_number(worksheet, 13, 0, 1209, format11);
-    
+
     /* Close the workbook, save the file and free any memory. */
     return workbook_close(workbook);
 }

examples/output_buffer.c

@@ -10,7 +10,7 @@
 #include "xlsxwriter.h"
 
 int main() {
-    char *output_buffer;
+    const char *output_buffer;
     size_t output_buffer_size;
 
     /* Set the worksheet options. */
@@ -36,7 +36,7 @@ int main() {
     FILE *file = fopen("output_buffer.xlsx", "wb");
     fwrite(output_buffer, output_buffer_size, 1, file);
     fclose(file);
-    free(output_buffer);
+    free((void *)output_buffer);
 
     return ferror(stdout);
 }

include/xlsxwriter/chart.h

@@ -699,7 +699,7 @@ typedef struct lxw_chart_pattern {
 typedef struct lxw_chart_font {
 
     /** The chart font name, such as "Arial" or "Calibri". */
-    char *name;
+    const char *name;
 
     /** The chart font size. The default is 11. */
     double size;
@@ -800,7 +800,7 @@ typedef struct lxw_chart_data_label {
 
     /** The string or formula value for the data label. See
      *  @ref chart_custom_labels. */
-    char *value;
+    const char *value;
 
     /** Option to hide/delete the data label from the chart series.
      *  See @ref chart_custom_labels. */

include/xlsxwriter/chartsheet.h

@@ -80,9 +80,9 @@ typedef struct lxw_chartsheet {
     struct lxw_protection_obj protection;
     uint8_t is_protected;
 
-    char *name;
-    char *quoted_name;
-    char *tmpdir;
+    const char *name;
+    const char *quoted_name;
+    const char *tmpdir;
     uint16_t index;
     uint8_t active;
     uint8_t selected;

include/xlsxwriter/packager.h

@@ -67,10 +67,10 @@ typedef struct lxw_packager {
     size_t output_buffer_size;
     zipFile zipfile;
     zip_fileinfo zipfile_info;
-    char *filename;
-    char *buffer;
+    const char *filename;
+    const char *buffer;
     char *output_buffer;
-    char *tmpdir;
+    const char *tmpdir;
     uint8_t use_zip64;
 
 } lxw_packager;
@@ -82,7 +82,7 @@ extern "C" {
 #endif
 /* *INDENT-ON* */
 
-lxw_packager *lxw_packager_new(const char *filename, char *tmpdir,
+lxw_packager *lxw_packager_new(const char *filename, const char *tmpdir,
                                uint8_t use_zip64);
 void lxw_packager_free(lxw_packager *packager);
 lxw_error lxw_create_package(lxw_packager *self);

include/xlsxwriter/styles.h

@@ -44,7 +44,7 @@ extern "C" {
 lxw_styles *lxw_styles_new(void);
 void lxw_styles_free(lxw_styles *styles);
 void lxw_styles_assemble_xml_file(lxw_styles *self);
-void lxw_styles_write_string_fragment(lxw_styles *self, char *string);
+void lxw_styles_write_string_fragment(lxw_styles *self, const char *string);
 void lxw_styles_write_rich_font(lxw_styles *styles, lxw_format *format);
 
 /* Declarations required for unit testing. */

include/xlsxwriter/utility.h

@@ -232,8 +232,8 @@ void lxw_str_tolower(char *str);
 #define lxw_strcasecmp strcasecmp
 #endif
 
-FILE *lxw_tmpfile(char *tmpdir);
-FILE *lxw_get_filehandle(char **buf, size_t *size, char *tmpdir);
+FILE *lxw_tmpfile(const char *tmpdir);
+FILE *lxw_get_filehandle(char **buf, size_t *size, const char *tmpdir);
 FILE *lxw_fopen(const char *filename, const char *mode);
 
 /* Use the third party dtoa function to avoid locale issues with sprintf

include/xlsxwriter/workbook.h

@@ -182,34 +182,34 @@ typedef struct lxw_defined_name {
  */
 typedef struct lxw_doc_properties {
     /** The title of the Excel Document. */
-    char *title;
+    const char *title;
 
     /** The subject of the Excel Document. */
-    char *subject;
+    const char *subject;
 
     /** The author of the Excel Document. */
-    char *author;
+    const char *author;
 
     /** The manager field of the Excel Document. */
-    char *manager;
+    const char *manager;
 
     /** The company field of the Excel Document. */
-    char *company;
+    const char *company;
 
     /** The category of the Excel Document. */
-    char *category;
+    const char *category;
 
     /** The keywords of the Excel Document. */
-    char *keywords;
+    const char *keywords;
 
     /** The comment field of the Excel Document. */
-    char *comments;
+    const char *comments;
 
     /** The status of the Excel Document. */
-    char *status;
+    const char *status;
 
     /** The hyperlink base URL of the Excel Document. */
-    char *hyperlink_base;
+    const char *hyperlink_base;
 
     /** The file creation date/time shown in Excel. This defaults to the
      * current time and date if set to 0. If you wish to create files that are
@@ -270,13 +270,13 @@ typedef struct lxw_workbook_options {
     uint8_t constant_memory;
 
     /** Directory to use for the temporary files created by libxlsxwriter. */
-    char *tmpdir;
+    const char *tmpdir;
 
     /** Allow ZIP64 extensions when creating the xlsx file zip container. */
     uint8_t use_zip64;
 
     /** Output buffer to use instead of writing to a file */
-    char **output_buffer;
+    const char **output_buffer;
 
     /** Used with output_buffer to get the size of the created buffer */
     size_t *output_buffer_size;